Revert "Forced pattern , separed to > 9 extruder"

This reverts commit 42b506ad85.

doc/MixedFilament.md

@@ -0,0 +1,171 @@
+# Mixed Filament
+
+Ported from [OrcaSlicer-FullSpectrum](https://github.com/SoftFever/OrcaSlicer-FullSpectrum)
+with contributions from Rad, Justin Hayes, Calogero Guagenti, xSil3nt, and ratdoux.
+
+---
+
+## User Guide
+
+### What It Does
+
+Mixed Filament lets a single virtual filament slot alternate between two
+physical filaments across layers (or within a layer in Pointillisme mode),
+producing blended or gradient-like colours on single-extruder printers.
+
+### Enabling
+
+1. Load a multi-colour (multi-extruder) profile with at least 2 filaments.
+2. The **Mixed Filaments** panel appears automatically in the right-hand sidebar
+   when 2 or more filaments are configured.
+3. Each auto-generated row represents one pair of physical filaments.
+   Toggle a row to enable it; the total filament count grows to include the
+   virtual slot.
+
+### Sidebar Workflow
+
+- **Add** — creates a custom row for the same pair or a different ratio.
+- **Edit** — opens `MixedFilamentConfigPanel` to adjust ratio, pattern,
+  surface offset (bias), and distribution mode.
+- **Delete** — marks the row deleted; existing painted geometry retains its
+  virtual filament ID until you re-slice or repaint.
+
+Painting with a virtual filament ID behaves the same as painting with a
+physical one — use the Multi-Material Painting gizmo and select the virtual
+slot from the colour palette.
+
+### Color Match Dialog
+
+Open via the colour swatch on a mixed row. The dialog (`MixedFilamentColorMatchDialog`)
+shows a live preview strip of the blended result and lets you adjust ratio
+until the preview matches your target colour. The preview accounts for
+surface-offset bias when enabled.
+
+### Anti-Banding Options
+
+| Setting | What it does |
+|---|---|
+| `mixed_filament_advanced_dithering` | Uses an ordered dither pattern instead of simple A-then-B runs. Reduces stripe visibility on some hue pairs. More experimental than the default. |
+| `dithering_local_z_mode` | Splits each blended layer into two sub-layers whose heights are proportional to the mix ratio (e.g. 66/33 at 0.12 mm → 0.08 mm + 0.04 mm). Produces the smoothest colour gradients. |
+| `dithering_local_z_whole_objects` | Extends Local-Z splitting beyond painted masks to cover the entire object cross-section. Useful when mixed walls surround a painted zone. |
+| `dithering_local_z_direct_multicolor` | For rows with 3 or more physical components, allocates Local-Z sub-layers directly across all components with carry-over error correction instead of collapsing to pair cadence. More toolchanges; less banding. |
+
+### Gotchas
+
+- **Single-extruder warning** — Mixed Filament requires a physical toolchange
+  between the two components. On a true single-nozzle printer this means a
+  manual filament swap. Verify your printer profile supports `T0`/`T1` before
+  using mixed slots in a production print.
+- **Variable-layer interaction** — If Variable Layer Height is enabled, Local-Z
+  sub-layer heights are recomputed per interval. The mix ratio is preserved but
+  the absolute sub-layer heights change with the variable height. Review the
+  layer preview after applying variable layers.
+- **Custom sequence disabled** — OrcaSlicer's "custom toolchange sequence" is
+  suppressed when mixed filaments are active (`PlateSettingsDialog`). The
+  virtual-to-physical resolution must control toolchange order; a user-defined
+  sequence would break it.
+- **Stable IDs** — each mixed row carries a `stable_id` (64-bit). If you
+  reorder or delete rows and then load an older project, the ID remap in
+  `PresetBundle::update_mixed_filament_id_remap` translates painted geometry
+  to the correct new virtual slot. Do not rely on the 1-based filament index
+  as a stable identifier.
+
+---
+
+## Developer Guide
+
+### Core Data Structures
+
+```
+src/libslic3r/MixedFilament.hpp   — MixedFilament struct, MixedFilamentManager
+src/libslic3r/MixedFilament.cpp   — serialization, resolve(), auto_generate()
+src/libslic3r/LocalZOrderOptimizer.hpp — bucket-ordering helpers for Local-Z
+```
+
+The key scalar fields on `MixedFilament`:
+
+- `component_a`, `component_b` — 1-based physical filament indices.
+- `ratio_a`, `ratio_b` — layer-alternation cadence numerators.
+- `mix_b_percent` — nominal colour mix (used for Local-Z height computation
+  and the Color Match preview; does not change the cadence).
+- `stable_id` — monotonically increasing 64-bit ID assigned at construction.
+  Never reused. Survives serialization round-trips.
+- `distribution_mode` — selects between `Simple`, `SameLayerPointillisme`,
+  and `GroupedManual`.
+
+### Seam: Adding New Distribution Modes
+
+`MixedFilamentManager::resolve()` in `MixedFilament.cpp` is the single
+dispatch point that maps `(virtual_filament_id, num_physical, layer_index)`
+to a physical extruder. The current switch covers `Simple` and
+`SameLayerPointillisme`. A new mode is added by:
+
+1. Adding a value to the `MixedFilament::DistributionMode` enum in
+   `MixedFilament.hpp`.
+2. Adding a `case` to `MixedFilamentManager::resolve()` in `MixedFilament.cpp`.
+3. Serializing the new mode token in `serialize_custom_entries` /
+   `load_custom_entries` (format is a semicolon-delimited row string; see
+   existing tokens for the convention).
+
+G-code emission (`src/libslic3r/GCode/`) reads only the physical ID returned
+by `resolve()`, so new modes are automatically emitted without further changes.
+
+### Seam: New Toolchange-Cost Heuristics
+
+`LocalZOrderOptimizer` (`src/libslic3r/LocalZOrderOptimizer.hpp`) exposes:
+
+- `order_bucket_extruders(bucket, current, preferred_last)` — reorders a
+  single-layer bucket to minimise toolchanges given the current active extruder.
+- `order_pass_group(group, current_extruder)` — greedy walk across a set of
+  buckets (one per Local-Z sub-layer) to minimise total transitions.
+
+To add a new heuristic (e.g. cost-based look-ahead), replace or wrap
+`order_pass_group`. The caller in `PrintObjectSlice.cpp` passes the result
+directly into the sub-layer plan, so the heuristic is fully decoupled from
+the plan builder.
+
+### Seam: New Picker Shapes in the Color Map Panel
+
+`MixedFilamentColorMapPanel` (`src/slic3r/GUI/MixedFilamentColorMapPanel.hpp`)
+renders a 2-D colour map using a set of geometry "types" (currently strip and
+gradient). Each type is a small self-contained rendering path keyed by an enum
+value. New shapes are added by:
+
+1. Adding an enum value to `MixedFilamentColorMapPanel::GeometryType`.
+2. Implementing the corresponding `Paint*` helper (follow `PaintStrip` as a
+   template).
+3. Wiring the new type into the `switch` in `OnPaint`.
+
+### Persistence (3MF)
+
+The entire mixed-filament state is stored as a single string key
+`mixed_filament_definitions` in the project config block (section `[presets]`
+in the 3MF metadata).
+
+Round-trip path:
+
+```
+MixedFilamentManager::serialize_custom_entries()
+  called by PresetBundle::sync_mixed_filaments_to_config()
+  written by bbs_3mf: store_bbs_3mf → config.set("presets", "mixed_filament_definitions", ...)
+
+load_bbs_3mf → config.get("presets", "mixed_filament_definitions")
+  stored in project_config["mixed_filament_definitions"]
+  read by PresetBundle::sync_mixed_filaments_from_config()
+    → mixed_filaments.auto_generate(colours)
+    → mixed_filaments.load_custom_entries(defs, colours)
+```
+
+Auto-generated rows are *not* written to the definitions string; they are
+rebuilt from the filament colour list. Only `custom == true` rows are stored.
+
+See `tests/fff_print/test_mixed_filament_e2e.cpp` for regression tests
+covering this path.
+
+### ID Remap
+
+When filaments are added, removed, or reordered, virtual IDs shift.
+`PresetBundle::update_mixed_filament_id_remap(old_mixed, old_count, new_count)`
+produces a `remap` vector where `remap[old_virtual_id] = new_virtual_id`.
+Painted triangle mesh face data uses these IDs; the remap is applied in
+`TriangleSelectorMixed` after any filament list change.

localization/i18n/list.txt

@@ -250,3 +250,7 @@ src/slic3r/GUI/RammingChart.cpp
 src/slic3r/GUI/StepMeshDialog.cpp
 src/slic3r/GUI/FilamentPickerDialog.hpp
 src/libslic3r/PresetBundle.cpp
+src/slic3r/GUI/MixedFilamentColorMatchDialog.cpp
+src/slic3r/GUI/MixedFilamentColorMatchDialog.hpp
+src/slic3r/GUI/MixedFilamentConfigPanel.cpp
+src/slic3r/GUI/MixedFilamentConfigPanel.hpp

src/libslic3r/AppConfig.cpp

@@ -408,6 +408,10 @@ void AppConfig::set_defaults()
         set("auto_calculate_flush","all");
     }
 
+    if (get("auto_generate_gradients").empty()) {
+        set_bool("auto_generate_gradients", true);
+    }
+
     if (get("show_canvas_zoom_button").empty()) {
         set_bool("show_canvas_zoom_button", true);
     }

src/libslic3r/CMakeLists.txt

@@ -176,6 +176,9 @@ set(lisbslic3r_sources
     Fill/Lightning/Layer.hpp
     Fill/Lightning/TreeNode.cpp
     Fill/Lightning/TreeNode.hpp
+    filament_mixer.cpp
+    filament_mixer.h
+    filament_mixer_model.h
     Flow.cpp
     Flow.hpp
     FlushVolCalc.cpp
@@ -286,6 +289,7 @@ set(lisbslic3r_sources
     Line.hpp
     LocalesUtils.cpp
     LocalesUtils.hpp
+    LocalZOrderOptimizer.hpp
     MarchingSquares.hpp
     Measure.cpp
     Measure.hpp
@@ -295,6 +299,8 @@ set(lisbslic3r_sources
     MinAreaBoundingBox.hpp
     MinimumSpanningTree.cpp
     MinimumSpanningTree.hpp
+    MixedFilament.cpp
+    MixedFilament.hpp
     miniz_extension.cpp
     miniz_extension.hpp
     ModelArrange.cpp

src/libslic3r/ExtrusionEntity.hpp

@@ -170,7 +170,8 @@ public:
     ExtrusionPath(ExtrusionRole role, double mm3_per_mm, float width, float height, bool no_extrusion = false) : mm3_per_mm(mm3_per_mm), width(width), height(height), m_role(role), m_no_extrusion(no_extrusion) {}
 
     ExtrusionPath(const ExtrusionPath &rhs)
-        : polyline(rhs.polyline)
+        : ExtrusionEntity(rhs)
+        , polyline(rhs.polyline)
         , overhang_degree(rhs.overhang_degree)
         , curve_degree(rhs.curve_degree)
         , mm3_per_mm(rhs.mm3_per_mm)
@@ -181,9 +182,12 @@ public:
         , m_can_reverse(rhs.m_can_reverse)
         , m_role(rhs.m_role)
         , m_no_extrusion(rhs.m_no_extrusion)
-    {}
+    {
+        this->inset_idx = rhs.inset_idx;
+    }
     ExtrusionPath(ExtrusionPath &&rhs)
-        : polyline(std::move(rhs.polyline))
+        : ExtrusionEntity(rhs)
+        , polyline(std::move(rhs.polyline))
         , overhang_degree(rhs.overhang_degree)
         , curve_degree(rhs.curve_degree)
         , mm3_per_mm(rhs.mm3_per_mm)
@@ -194,9 +198,12 @@ public:
         , m_can_reverse(rhs.m_can_reverse)
         , m_role(rhs.m_role)
         , m_no_extrusion(rhs.m_no_extrusion)
-    {}
+    {
+        this->inset_idx = rhs.inset_idx;
+    }
     ExtrusionPath(const Polyline3 &polyline, const ExtrusionPath &rhs)
-        : polyline(polyline)
+        : ExtrusionEntity(rhs)
+        , polyline(polyline)
         , overhang_degree(rhs.overhang_degree)
         , curve_degree(rhs.curve_degree)
         , mm3_per_mm(rhs.mm3_per_mm)
@@ -207,9 +214,12 @@ public:
         , m_can_reverse(rhs.m_can_reverse)
         , m_role(rhs.m_role)
         , m_no_extrusion(rhs.m_no_extrusion)
-    {}
+    {
+        this->inset_idx = rhs.inset_idx;
+    }
     ExtrusionPath(Polyline3 &&polyline, const ExtrusionPath &rhs)
-        : polyline(std::move(polyline))
+        : ExtrusionEntity(rhs)
+        , polyline(std::move(polyline))
         , overhang_degree(rhs.overhang_degree)
         , curve_degree(rhs.curve_degree)
         , mm3_per_mm(rhs.mm3_per_mm)
@@ -220,7 +230,9 @@ public:
         , m_can_reverse(rhs.m_can_reverse)
         , m_role(rhs.m_role)
         , m_no_extrusion(rhs.m_no_extrusion)
-    {}
+    {
+        this->inset_idx = rhs.inset_idx;
+    }
 
     ExtrusionPath& operator=(const ExtrusionPath& rhs) {
         m_can_reverse = rhs.m_can_reverse;
@@ -234,6 +246,7 @@ public:
         this->overhang_degree = rhs.overhang_degree;
         this->curve_degree = rhs.curve_degree;
         this->polyline = rhs.polyline;
+        this->inset_idx = rhs.inset_idx;
         return *this;
     }
     ExtrusionPath& operator=(ExtrusionPath&& rhs) {
@@ -248,6 +261,7 @@ public:
         this->overhang_degree = rhs.overhang_degree;
         this->curve_degree = rhs.curve_degree;
         this->polyline = std::move(rhs.polyline);
+        this->inset_idx = rhs.inset_idx;
         return *this;
     }
 
@@ -380,20 +394,31 @@ public:
     ExtrusionPaths paths;
 
     ExtrusionMultiPath() {}
-    ExtrusionMultiPath(const ExtrusionMultiPath &rhs) : paths(rhs.paths), m_can_reverse(rhs.m_can_reverse) {}
-    ExtrusionMultiPath(ExtrusionMultiPath &&rhs) : paths(std::move(rhs.paths)), m_can_reverse(rhs.m_can_reverse) {}
-    ExtrusionMultiPath(const ExtrusionPaths &paths) : paths(paths) {}
-    ExtrusionMultiPath(const ExtrusionPath &path) {this->paths.push_back(path); m_can_reverse = path.can_reverse(); }
+    ExtrusionMultiPath(const ExtrusionMultiPath &rhs) : ExtrusionEntity(rhs), paths(rhs.paths), m_can_reverse(rhs.m_can_reverse) {}
+    ExtrusionMultiPath(ExtrusionMultiPath &&rhs) : ExtrusionEntity(rhs), paths(std::move(rhs.paths)), m_can_reverse(rhs.m_can_reverse) {}
+    ExtrusionMultiPath(const ExtrusionPaths &paths) : paths(paths)
+    {
+        if (!paths.empty())
+            this->inset_idx = paths.front().inset_idx;
+    }
+    ExtrusionMultiPath(const ExtrusionPath &path)
+    {
+        this->paths.push_back(path);
+        this->inset_idx = path.inset_idx;
+        m_can_reverse = path.can_reverse();
+    }
 
     ExtrusionMultiPath &operator=(const ExtrusionMultiPath &rhs)
     {
         this->paths     = rhs.paths;
+        this->inset_idx = rhs.inset_idx;
         m_can_reverse   = rhs.m_can_reverse;
         return *this;
     }
     ExtrusionMultiPath &operator=(ExtrusionMultiPath &&rhs)
     {
         this->paths     = std::move(rhs.paths);
+        this->inset_idx = rhs.inset_idx;
         m_can_reverse   = rhs.m_can_reverse;
         return *this;
     }
@@ -447,12 +472,27 @@ public:
     ExtrusionPaths paths;
 
     ExtrusionLoop(ExtrusionLoopRole role = elrDefault) : m_loop_role(role) {}
-    ExtrusionLoop(const ExtrusionPaths &paths, ExtrusionLoopRole role = elrDefault) : paths(paths), m_loop_role(role) {}
-    ExtrusionLoop(ExtrusionPaths &&paths, ExtrusionLoopRole role = elrDefault) : paths(std::move(paths)), m_loop_role(role) {}
+    ExtrusionLoop(const ExtrusionPaths &paths, ExtrusionLoopRole role = elrDefault) : paths(paths), m_loop_role(role)
+    {
+        if (!paths.empty())
+            this->inset_idx = paths.front().inset_idx;
+    }
+    ExtrusionLoop(ExtrusionPaths &&paths, ExtrusionLoopRole role = elrDefault) : paths(std::move(paths)), m_loop_role(role)
+    {
+        if (!this->paths.empty())
+            this->inset_idx = this->paths.front().inset_idx;
+    }
     ExtrusionLoop(const ExtrusionPath &path, ExtrusionLoopRole role = elrDefault) : m_loop_role(role)
-        { this->paths.push_back(path); }
+    {
+        this->paths.push_back(path);
+        this->inset_idx = path.inset_idx;
+    }
     ExtrusionLoop(const ExtrusionPath &&path, ExtrusionLoopRole role = elrDefault) : m_loop_role(role)
-        { this->paths.emplace_back(std::move(path)); }
+    {
+        this->paths.emplace_back(std::move(path));
+        if (!this->paths.empty())
+            this->inset_idx = this->paths.front().inset_idx;
+    }
     bool is_loop() const override{ return true; }
     bool can_reverse() const override { return false; }
 	ExtrusionEntity* clone() const override{ return new ExtrusionLoop (*this); }

src/libslic3r/Format/bbs_3mf.cpp

@@ -11,6 +11,7 @@
 #include "../Time.hpp"
 
 #include "../I18N.hpp"
+#include "../MixedFilament.hpp"
 
 #include "bbs_3mf.hpp"
 
@@ -2223,7 +2224,32 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
         }
 
         const ConfigOptionStrings* filament_ids_opt = config.option<ConfigOptionStrings>("filament_settings_id");
-        int max_filament_id = filament_ids_opt ? filament_ids_opt->size() : std::numeric_limits<int>::max();
+        size_t physical_count = filament_ids_opt ? filament_ids_opt->size() : 0;
+        size_t max_filament_id_sz = physical_count;
+        if (filament_ids_opt != nullptr) {
+            const ConfigOptionString* mixed_opt = config.option<ConfigOptionString>("mixed_filament_definitions");
+            if (mixed_opt != nullptr && !mixed_opt->value.empty() && physical_count >= 2) {
+                std::vector<std::string> physical_colors;
+                if (const auto* colour_opt = config.option<ConfigOptionStrings>("filament_colour"))
+                    physical_colors = colour_opt->values;
+                else if (const auto* default_colour_opt = config.option<ConfigOptionStrings>("default_filament_colour"))
+                    physical_colors = default_colour_opt->values;
+                if (physical_colors.size() < physical_count)
+                    physical_colors.resize(physical_count, "#FFFFFF");
+                else if (physical_colors.size() > physical_count)
+                    physical_colors.resize(physical_count);
+
+                MixedFilamentManager mixed_mgr;
+                mixed_mgr.auto_generate(physical_colors);
+                mixed_mgr.load_custom_entries(mixed_opt->value, physical_colors);
+                max_filament_id_sz = mixed_mgr.total_filaments(physical_count);
+            }
+        } else {
+            max_filament_id_sz = size_t(std::numeric_limits<int>::max());
+        }
+        const int max_filament_id = max_filament_id_sz >= size_t(std::numeric_limits<int>::max())
+            ? std::numeric_limits<int>::max()
+            : int(max_filament_id_sz);
         for (ModelObject* mo : m_model->objects) {
             const ConfigOptionInt* extruder_opt = dynamic_cast<const ConfigOptionInt*>(mo->config.option("extruder"));
             int extruder_id = 0;

src/libslic3r/GCode.hpp

@@ -81,17 +81,23 @@ public:
         const Vec3d                                                  plate_origin,
         const std::vector<WipeTower::ToolChangeResult>              &priming,
         const std::vector<std::vector<WipeTower::ToolChangeResult>> &tool_changes,
+        const std::vector<std::vector<WipeTower::ToolChangeResult>> &local_z_tool_changes,
         const WipeTower::ToolChangeResult                           &final_purge,
-        const std::vector<unsigned int>                             &slice_used_filaments) :
+        const std::vector<unsigned int>                             &slice_used_filaments,
+        const std::vector<std::vector<WipeTower::box_coordinates>>  &local_z_reserve_boxes = {}) :
         m_left(/*float(print_config.wipe_tower_x.value)*/ 0.f),
         m_right(float(/*print_config.wipe_tower_x.value +*/ print_config.prime_tower_width.value)),
         m_wipe_tower_pos(float(print_config.wipe_tower_x.get_at(plate_idx)), float(print_config.wipe_tower_y.get_at(plate_idx))),
         m_wipe_tower_rotation(float(print_config.wipe_tower_rotation_angle)),
         m_priming(priming),
         m_tool_changes(tool_changes),
+        m_local_z_tool_changes(local_z_tool_changes),
+        m_local_z_reserve_boxes(local_z_reserve_boxes),
         m_final_purge(final_purge),
         m_layer_idx(-1),
         m_tool_change_idx(0),
+        m_local_z_tool_change_idx(local_z_tool_changes.size(), 0),
+        m_local_z_reserve_slot_idx(local_z_reserve_boxes.size(), 0),
         m_plate_origin(plate_origin),
         m_single_extruder_multi_material(print_config.single_extruder_multi_material),
         m_enable_timelapse_print(print_config.timelapse_type.value == TimelapseType::tlSmooth),
@@ -108,8 +114,18 @@ public:
     }
 
     std::string prime(GCode &gcodegen);
-    void next_layer() { ++ m_layer_idx; m_tool_change_idx = 0; }
-    std::string tool_change(GCode &gcodegen, int extruder_id, bool finish_layer);
+    void next_layer() {
+        ++ m_layer_idx;
+        m_tool_change_idx = 0;
+        if (m_layer_idx >= 0 && size_t(m_layer_idx) < m_local_z_tool_change_idx.size())
+            m_local_z_tool_change_idx[size_t(m_layer_idx)] = 0;
+        if (m_layer_idx >= 0 && size_t(m_layer_idx) < m_local_z_reserve_slot_idx.size())
+            m_local_z_reserve_slot_idx[size_t(m_layer_idx)] = 0;
+    }
+    // If local_z_unplanned is true, emit a wipe/toolchange without consuming the preplanned
+    // per-layer wipe-tower sequence (used by Local-Z phase-b extra toolchanges).
+    std::string tool_change(GCode &gcodegen, int extruder_id, bool finish_layer, bool local_z_unplanned = false,
+                            double local_z_nominal_layer_z = -1.);
     bool is_empty_wipe_tower_gcode(GCode &gcodegen, int extruder_id, bool finish_layer);
     std::string finalize(GCode &gcodegen);
     std::vector<float> used_filament_length() const;
@@ -140,10 +156,15 @@ private:
     // Reference to cached values at the Printer class.
     const std::vector<WipeTower::ToolChangeResult>              &m_priming;
     const std::vector<std::vector<WipeTower::ToolChangeResult>> &m_tool_changes;
+    const std::vector<std::vector<WipeTower::ToolChangeResult>> &m_local_z_tool_changes;
+    const std::vector<std::vector<WipeTower::box_coordinates>>   m_local_z_reserve_boxes;
     const WipeTower::ToolChangeResult                           &m_final_purge;
     // Current layer index.
     int                                                          m_layer_idx;
     int                                                          m_tool_change_idx;
+    std::vector<size_t>                                          m_local_z_tool_change_idx;
+    // Per-layer next-available slot index for Local-Z unplanned toolchanges.
+    std::vector<size_t>                                          m_local_z_reserve_slot_idx;
     double                                                       m_last_wipe_tower_print_z;
 
     // BBS
@@ -385,6 +406,16 @@ private:
     void check_placeholder_parser_failed();
     size_t get_extruder_id(unsigned int filament_id) const;
 
+    // Mixed-filament resolution: convert a virtual 1-based filament ID to a zero-based
+    // physical extruder ID ready to pass to set_extruder(). When mixed_mgr is null or
+    // the ID is not a mixed slot the call is a no-op (returns virtual_id_1based - 1).
+    unsigned int resolve_extruder_for_layer(unsigned int virtual_id_1based,
+                                            const LayerTools &layer_tools) const
+    {
+        const unsigned int resolved_1based = layer_tools.resolve_mixed_1based(virtual_id_1based);
+        return resolved_1based == 0 ? 0 : resolved_1based - 1;
+    }
+
     void            set_last_pos(const Point &pos) { m_last_pos = Point3(pos, 0); m_last_pos_defined = true; }
     void            set_last_pos(const Point3 &pos) { m_last_pos = pos; m_last_pos_defined = true; }
     bool            last_pos_defined() const { return m_last_pos_defined; }

src/libslic3r/GCode/ToolOrdering.cpp

@@ -20,6 +20,7 @@
 #include <cassert>
 #include <limits>
 #include <algorithm>
+#include <cmath>
 #include <unordered_map>
 
 #include <libslic3r.h>
@@ -36,6 +37,137 @@ namespace Slic3r {
 const static bool g_wipe_into_objects = false;
 constexpr double similar_color_threshold_de2000 = 20.0;
 
+// ---------------------------------------------------------------------------
+// Anonymous-namespace helpers for mixed-filament resolution
+// ---------------------------------------------------------------------------
+namespace {
+
+// Resolve a 1-based filament ID through the mixed-filament manager, taking the
+// optional per-object layer-height cadence (a/b) into account.
+// Returns the resolved 1-based physical ID, or the input unchanged when the ID
+// is not a mixed slot.
+unsigned int resolve_mixed_with_layer_heights(const MixedFilamentManager *mixed_mgr,
+                                              size_t                      num_physical,
+                                              unsigned int                filament_id_1based,
+                                              int                         layer_index,
+                                              float                       layer_print_z,
+                                              float                       layer_height,
+                                              float                       layer_height_a,
+                                              float                       layer_height_b,
+                                              float                       base_layer_height)
+{
+    if (!(mixed_mgr && mixed_mgr->is_mixed(filament_id_1based, num_physical)))
+        return filament_id_1based;
+
+    const MixedFilament *mixed_row = mixed_mgr->mixed_filament_from_id(filament_id_1based, num_physical);
+    const bool is_custom_mixed = mixed_row != nullptr && mixed_row->custom;
+
+    if (!is_custom_mixed && (layer_height_a > 0.f || layer_height_b > 0.f)) {
+        const float safe_base = std::max<float>(0.01f, base_layer_height);
+        const int ratio_a = std::max(1, int(std::lround((layer_height_a > 0.f ? layer_height_a : safe_base) / safe_base)));
+        const int ratio_b = std::max(1, int(std::lround((layer_height_b > 0.f ? layer_height_b : safe_base) / safe_base)));
+        const int cycle   = ratio_a + ratio_b;
+
+        if (cycle > 0 && mixed_row != nullptr) {
+            const int pos = ((layer_index % cycle) + cycle) % cycle;
+            return pos < ratio_a ? mixed_row->component_a : mixed_row->component_b;
+        }
+    }
+
+    return mixed_mgr->resolve(filament_id_1based, num_physical, layer_index, layer_print_z, layer_height);
+}
+
+bool has_grouped_manual_pattern(const MixedFilamentManager *mixed_mgr,
+                                size_t                      num_physical,
+                                unsigned int                filament_id_1based)
+{
+    if (!(mixed_mgr && mixed_mgr->is_mixed(filament_id_1based, num_physical)))
+        return false;
+    const MixedFilament *mixed_row = mixed_mgr->mixed_filament_from_id(filament_id_1based, num_physical);
+    if (mixed_row == nullptr)
+        return false;
+    const std::string normalized = MixedFilamentManager::normalize_manual_pattern(mixed_row->manual_pattern);
+    return normalized.find(',') != std::string::npos;
+}
+
+void append_unique_preserve_order(std::vector<unsigned int> &dst, unsigned int value)
+{
+    if (std::find(dst.begin(), dst.end(), value) == dst.end())
+        dst.emplace_back(value);
+}
+
+bool internal_solid_infill_uses_sparse_filament(const PrintRegion &region, ExtrusionRole role)
+{
+    return role == erSolidInfill && std::abs(region.config().sparse_infill_density.value - 100.) < EPSILON;
+}
+
+bool use_base_infill_filament_impl(const LayerTools &layer_tools, const PrintRegion &region)
+{
+    const PrintRegionConfig &config = region.config();
+
+    // Keep legacy "Filament for Features" behavior: an explicit sparse infill
+    // filament choice (different from wall filament) is an override even if the
+    // dedicated toggle is missing or false in the loaded config.
+    const bool explicit_sparse_override =
+        config.sparse_infill_filament.value > 0 &&
+        config.wall_filament.value > 0 &&
+        config.sparse_infill_filament.value != config.wall_filament.value;
+
+    if (!config.enable_infill_filament_override.value && !explicit_sparse_override)
+        return true;
+    if (layer_tools.object_layer_count <= 0)
+        return false;
+
+    const int first_layers = std::max(0, config.infill_filament_use_base_first_layers.value);
+    const int last_layers  = std::max(0, config.infill_filament_use_base_last_layers.value);
+    return layer_tools.layer_index < first_layers || layer_tools.layer_index >= layer_tools.object_layer_count - last_layers;
+}
+
+unsigned int sparse_infill_filament_id_1based_impl(const LayerTools &layer_tools, const PrintRegion &region)
+{
+    return use_base_infill_filament_impl(layer_tools, region) ? region.config().wall_filament.value : region.config().sparse_infill_filament.value;
+}
+
+unsigned int grouped_manual_pattern_mixed_filament_id_for_layer(const LayerTools&  layer_tools,
+                                                                unsigned int       configured_filament_id_1based)
+{
+    if (layer_tools.mixed_mgr == nullptr || layer_tools.num_physical == 0)
+        return 0;
+    if (has_grouped_manual_pattern(layer_tools.mixed_mgr, layer_tools.num_physical, configured_filament_id_1based))
+        return configured_filament_id_1based;
+    return 0;
+}
+
+unsigned int grouped_manual_pattern_infill_filament_1based(const LayerTools&  layer_tools,
+                                                           const PrintRegion& region,
+                                                           unsigned int       configured_filament_id_1based)
+{
+    const unsigned int grouped_id =
+        grouped_manual_pattern_mixed_filament_id_for_layer(layer_tools, configured_filament_id_1based);
+    if (grouped_id == 0)
+        return 0;
+
+    const int innermost_perimeter_index = std::max(0, region.config().wall_loops.value - 1);
+    return layer_tools.mixed_mgr->resolve_perimeter(grouped_id,
+                                                    layer_tools.num_physical,
+                                                    layer_tools.layer_index,
+                                                    innermost_perimeter_index,
+                                                    float(layer_tools.print_z),
+                                                    float(layer_tools.layer_height));
+}
+
+void remove_duplicates_preserve_order(std::vector<unsigned int> &values)
+{
+    std::vector<unsigned int> ordered;
+    ordered.reserve(values.size());
+    for (unsigned int value : values)
+        append_unique_preserve_order(ordered, value);
+    values = std::move(ordered);
+}
+
+} // anonymous namespace
+// ---------------------------------------------------------------------------
+
 static std::set<int>get_filament_by_type(const std::vector<unsigned int>& used_filaments, const PrintConfig* print_config, const std::string& type)
 {
     std::set<int> target_filaments;
@@ -79,23 +211,50 @@ bool check_filament_printable_after_group(const std::vector<unsigned int> &used_
     return true;
 }
 
+// Resolve a 1-based filament ID through the mixed-filament manager for this layer.
+unsigned int LayerTools::resolve_mixed_1based(unsigned int filament_id_1based) const
+{
+    if (!mixed_mgr || filament_id_1based == 0)
+        return filament_id_1based;
+    return resolve_mixed_with_layer_heights(mixed_mgr,
+                                            num_physical,
+                                            filament_id_1based,
+                                            this->layer_index,
+                                            static_cast<float>(this->print_z),
+                                            static_cast<float>(this->layer_height),
+                                            mixed_layer_height_a,
+                                            mixed_layer_height_b,
+                                            mixed_base_layer_height);
+}
+
 // Return a zero based extruder from the region, or extruder_override if overriden.
 unsigned int LayerTools::wall_filament(const PrintRegion &region) const
 {
 	assert(region.config().wall_filament.value > 0);
-	return ((this->extruder_override == 0) ? region.config().wall_filament.value : this->extruder_override) - 1;
+	unsigned int id_1based = (this->extruder_override == 0)
+        ? region.config().wall_filament.value
+        : this->extruder_override;
+	return resolve_mixed_1based(id_1based) - 1;
 }
 
 unsigned int LayerTools::sparse_infill_filament(const PrintRegion &region) const
 {
 	assert(region.config().sparse_infill_filament.value > 0);
-	return ((this->extruder_override == 0) ? region.config().sparse_infill_filament.value : this->extruder_override) - 1;
+	unsigned int id_1based = (this->extruder_override == 0)
+        ? sparse_infill_filament_id_1based_impl(*this, region)
+        : this->extruder_override;
+    const unsigned int grouped = grouped_manual_pattern_infill_filament_1based(*this, region, id_1based);
+	return ((grouped != 0) ? grouped : resolve_mixed_1based(id_1based)) - 1;
 }
 
 unsigned int LayerTools::solid_infill_filament(const PrintRegion &region) const
 {
 	assert(region.config().solid_infill_filament.value > 0);
-	return ((this->extruder_override == 0) ? region.config().solid_infill_filament.value : this->extruder_override) - 1;
+	unsigned int id_1based = (this->extruder_override == 0)
+        ? region.config().solid_infill_filament.value
+        : this->extruder_override;
+    const unsigned int grouped = grouped_manual_pattern_infill_filament_1based(*this, region, id_1based);
+	return ((grouped != 0) ? grouped : resolve_mixed_1based(id_1based)) - 1;
 }
 
 // Returns a zero based extruder this eec should be printed with, according to PrintRegion config or extruder_override if overriden.
@@ -104,20 +263,29 @@ unsigned int LayerTools::extruder(const ExtrusionEntityCollection &extrusions, c
 	assert(region.config().wall_filament.value > 0);
 	assert(region.config().sparse_infill_filament.value > 0);
 	assert(region.config().solid_infill_filament.value > 0);
-	// 1 based extruder ID.
-    unsigned int extruder = 1;
-    if (this->extruder_override == 0) {
     if (extrusions.has_infill()) {
-            if (extrusions.has_solid_infill())
-                extruder = region.config().solid_infill_filament;
-            else
-                extruder = region.config().sparse_infill_filament;
-        } else
-            extruder = region.config().wall_filament.value;
-    } else
-        extruder = this->extruder_override;
+        const ExtrusionRole role = extrusions.entities.empty() ? erNone : extrusions.entities.front()->role();
+        if (internal_solid_infill_uses_sparse_filament(region, role))
+            return sparse_infill_filament(region);
+        return is_solid_infill(role) ? solid_infill_filament(region) : sparse_infill_filament(region);
+    }
+    return wall_filament(region);
+}
 
-    return (extruder == 0) ? 0 : extruder - 1;
+unsigned int LayerTools::sparse_infill_filament_id_1based(const PrintRegion &region) const
+{
+    return sparse_infill_filament_id_1based_impl(*this, region);
+}
+
+unsigned int LayerTools::infill_filament_id_1based(const PrintRegion &region) const
+{
+    // Default role: erInternalInfill routes through sparse path.
+    return sparse_infill_filament_id_1based_impl(*this, region);
+}
+
+bool LayerTools::use_base_infill_filament(const PrintRegion &region) const
+{
+    return use_base_infill_filament_impl(*this, region);
 }
 
 static double calc_max_layer_height(const PrintConfig &config, double max_object_layer_height)
@@ -179,6 +347,7 @@ void ToolOrdering::handle_dontcare_extruder(const std::vector<unsigned int>& too
     // Reorder the extruders of first layer
     {
         LayerTools& lt = m_layer_tools[0];
+        if (!lt.preserve_extruder_order) {
             std::vector<unsigned int> layer0_extruders = lt.extruders;
             lt.extruders.clear();
             for (unsigned int extruder_id : tool_order_layer0) {
@@ -202,6 +371,7 @@ void ToolOrdering::handle_dontcare_extruder(const std::vector<unsigned int>& too
                 lt.extruders.push_back(tool_order_layer0[0]);
             }
         }
+    }
 
     int last_extruder_id = m_layer_tools[0].extruders.back();
     for (int i = 1; i < m_layer_tools.size(); i++) {
@@ -215,6 +385,10 @@ void ToolOrdering::handle_dontcare_extruder(const std::vector<unsigned int>& too
             if (lt.extruders.front() == 0)
                 // Pop the "don't care" extruder, the "don't care" region will be merged with the next one.
                 lt.extruders.erase(lt.extruders.begin());
+            if (lt.preserve_extruder_order) {
+                last_extruder_id = lt.extruders.back();
+                continue;
+            }
             // Reorder the extruders to start with the last one.
             for (size_t i = 1; i < lt.extruders.size(); ++i)
                 if (lt.extruders[i] == last_extruder_id) {
@@ -269,6 +443,10 @@ void ToolOrdering::handle_dontcare_extruder(unsigned int last_extruder_id)
             if (lt.extruders.front() == 0)
                 // Pop the "don't care" extruder, the "don't care" region will be merged with the next one.
                 lt.extruders.erase(lt.extruders.begin());
+            if (lt.preserve_extruder_order) {
+                last_extruder_id = lt.extruders.back();
+                continue;
+            }
             // Reorder the extruders to start with the last one.
             for (size_t i = 1; i < lt.extruders.size(); ++ i)
                 if (lt.extruders[i] == last_extruder_id) {
@@ -384,6 +562,10 @@ ToolOrdering::ToolOrdering(const PrintObject &object, unsigned int first_extrude
     m_print_full_config = &object.print()->full_print_config();
     m_print_object_ptr = &object;
     m_print = const_cast<Print*>(object.print());
+    // Mixed filament support.
+    m_mixed_mgr    = &object.print()->mixed_filament_manager();
+    m_num_physical = object.print()->config().filament_colour.values.size();
+    update_mixed_layer_height_settings();
     if (object.layers().empty())
         return;
 
@@ -429,6 +611,10 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
     m_print_full_config = &print.full_print_config();
     m_print = const_cast<Print *>(&print);  // for update the context of print
     m_print_config_ptr = &print.config();
+    // Mixed filament support.
+    m_mixed_mgr    = &print.mixed_filament_manager();
+    m_num_physical = print.config().filament_colour.values.size();
+    update_mixed_layer_height_settings();
 
     // Initialize the print layers for all objects and all layers.
     coordf_t max_layer_height = 0.;
@@ -481,6 +667,33 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
     this->mark_skirt_layers(print.config(), max_layer_height);
 }
 
+void ToolOrdering::update_mixed_layer_height_settings()
+{
+    const PrintConfig *cfg = m_print_config_ptr;
+    if (cfg == nullptr && m_print_object_ptr != nullptr)
+        cfg = &m_print_object_ptr->print()->config();
+
+    m_mixed_layer_height_a = 0.f;
+    m_mixed_layer_height_b = 0.f;
+    if (m_print_full_config != nullptr &&
+        m_print_full_config->has("mixed_color_layer_height_a") &&
+        m_print_full_config->has("mixed_color_layer_height_b")) {
+        m_mixed_layer_height_a = float(m_print_full_config->opt_float("mixed_color_layer_height_a"));
+        m_mixed_layer_height_b = float(m_print_full_config->opt_float("mixed_color_layer_height_b"));
+    } else if (cfg != nullptr) {
+        m_mixed_layer_height_a = cfg->mixed_color_layer_height_a.value;
+        m_mixed_layer_height_b = cfg->mixed_color_layer_height_b.value;
+    }
+
+    float base_height = 0.2f;
+    if (m_print_object_ptr != nullptr)
+        base_height = float(m_print_object_ptr->config().layer_height.value);
+    else if (m_print_full_config != nullptr && m_print_full_config->has("layer_height"))
+        base_height = float(m_print_full_config->opt_float("layer_height"));
+
+    m_mixed_base_layer_height = std::max<float>(0.01f, base_height);
+}
+
 static void apply_first_layer_order(const DynamicPrintConfig* config, std::vector<unsigned int>& tool_order) {
     const ConfigOptionInts* first_layer_print_sequence_op = config->option<ConfigOptionInts>("first_layer_print_sequence");
     if (first_layer_print_sequence_op) {
@@ -646,6 +859,15 @@ void ToolOrdering::initialize_layers(std::vector<coordf_t> &zs)
 // Collect extruders reuqired to print layers.
 void ToolOrdering::collect_extruders(const PrintObject &object, const std::vector<std::pair<double, unsigned int>> &per_layer_extruder_switches)
 {
+    // Propagate mixed-filament context to all LayerTools entries.
+    for (LayerTools &lt : m_layer_tools) {
+        lt.mixed_mgr               = m_mixed_mgr;
+        lt.num_physical            = m_num_physical;
+        lt.mixed_layer_height_a    = m_mixed_layer_height_a;
+        lt.mixed_layer_height_b    = m_mixed_layer_height_b;
+        lt.mixed_base_layer_height = m_mixed_base_layer_height;
+    }
+
     // Extruder overrides are ordered by print_z.
     std::vector<std::pair<double, unsigned int>>::const_iterator it_per_layer_extruder_override;
 	it_per_layer_extruder_override = per_layer_extruder_switches.begin();
@@ -659,6 +881,10 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
     // Collect the object extruders.
     for (auto layer : object.layers()) {
         LayerTools &layer_tools = this->tools_for_layer(layer->print_z);
+        // Store the sequential layer index and height for mixed-filament resolution.
+        layer_tools.layer_index        = layerCount;
+        layer_tools.object_layer_count = static_cast<int>(object.layers().size());
+        layer_tools.layer_height       = layer->height;
 
         // Override extruder with the next
     	for (; it_per_layer_extruder_override != per_layer_extruder_switches.end() && it_per_layer_extruder_override->first < layer->print_z + EPSILON; ++ it_per_layer_extruder_override)
@@ -682,9 +908,40 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
                 }
 
                 if (something_nonoverriddable){
-               		layer_tools.extruders.emplace_back((extruder_override == 0) ? region.config().wall_filament.value : extruder_override);
-                    if (layerCount == 0) {
-                        firstLayerExtruders.emplace_back((extruder_override == 0) ? region.config().wall_filament.value : extruder_override);
+                    const unsigned int configured_wall = (extruder_override == 0)
+                        ? region.config().wall_filament.value
+                        : extruder_override;
+                    unsigned int       wall_ext        = resolve_mixed(configured_wall,
+                                                                       layerCount,
+                                                                       float(layer->print_z),
+                                                                       float(layer->height));
+                    const unsigned int grouped_id =
+                        grouped_manual_pattern_mixed_filament_id_for_layer(layer_tools, configured_wall);
+                    if (grouped_id != 0) {
+                        const std::vector<unsigned int> ordered =
+                            m_mixed_mgr->ordered_perimeter_extruders(grouped_id,
+                                                                     m_num_physical,
+                                                                     layerCount,
+                                                                     float(layer->print_z),
+                                                                     float(layer->height));
+                        if (!ordered.empty()) {
+                            if (ordered.size() >= 2)
+                                layer_tools.preserve_extruder_order = true;
+                            for (unsigned int extruder_id : ordered) {
+                                layer_tools.extruders.emplace_back(extruder_id);
+                                if (layerCount == 0 &&
+                                    std::find(firstLayerExtruders.begin(), firstLayerExtruders.end(), int(extruder_id)) == firstLayerExtruders.end())
+                                    firstLayerExtruders.emplace_back(int(extruder_id));
+                            }
+                        } else {
+                            layer_tools.extruders.emplace_back(wall_ext);
+                            if (layerCount == 0)
+                                firstLayerExtruders.emplace_back(wall_ext);
+                        }
+                    } else {
+                        layer_tools.extruders.emplace_back(wall_ext);
+                        if (layerCount == 0)
+                            firstLayerExtruders.emplace_back(wall_ext);
                     }
                 }
 
@@ -712,11 +969,15 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
             if (something_nonoverriddable || !m_print_config_ptr) {
                 if (extruder_override == 0) {
                     if (has_solid_infill)
-	                    layer_tools.extruders.emplace_back(region.config().solid_infill_filament);
+                        layer_tools.extruders.emplace_back(layer_tools.solid_infill_filament(region) + 1);
                     if (has_infill)
-	                    layer_tools.extruders.emplace_back(region.config().sparse_infill_filament);
-            	} else if (has_solid_infill || has_infill)
-            		layer_tools.extruders.emplace_back(extruder_override);
+                        layer_tools.extruders.emplace_back(layer_tools.sparse_infill_filament(region) + 1);
+                } else if (has_solid_infill || has_infill) {
+                    layer_tools.extruders.emplace_back(resolve_mixed(extruder_override,
+                                                                     layerCount,
+                                                                     float(layer->print_z),
+                                                                     float(layer->height)));
+                }
             }
             if (has_solid_infill || has_infill)
                 layer_tools.has_object = true;
@@ -730,18 +991,23 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
     // Collect the support extruders.
     for (auto support_layer : object.support_layers()) {
         LayerTools   &layer_tools = this->tools_for_layer(support_layer->print_z);
+        layer_tools.layer_height  = support_layer->height;
         ExtrusionRole role        = support_layer->support_fills.role();
-        bool          has_support   = false;
-        bool          has_interface = false;
-        for (const ExtrusionEntity *ee : support_layer->support_fills.entities) {
-            ExtrusionRole er = ee->role();
-            if (er == erSupportMaterial || er == erSupportTransition) has_support = true;
-            if (er == erSupportMaterialInterface) has_interface = true;
-            if (has_support && has_interface) break;
-        }
-        unsigned int extruder_support   = object.config().support_filament.value;
-        unsigned int extruder_interface = object.config().support_interface_filament.value;
+        bool has_support   = role == erMixed || role == erSupportMaterial || role == erSupportTransition;
+        bool has_interface = role == erMixed || role == erSupportMaterialInterface;
+
+        unsigned int extruder_support   = resolve_mixed(object.config().support_filament.value,
+                                                        layer_tools.layer_index,
+                                                        float(support_layer->print_z),
+                                                        float(support_layer->height));
+        unsigned int extruder_interface = resolve_mixed(object.config().support_interface_filament.value,
+                                                        layer_tools.layer_index,
+                                                        float(support_layer->print_z),
+                                                        float(support_layer->height));
+
         if (has_support) {
+            // BP-only fallback: when support_filament is unset and an interface
+            // exists, pick the lowest-flush non-soluble body extruder.
             if (extruder_support > 0 || !has_interface || extruder_interface == 0 || layer_tools.has_object)
                 layer_tools.extruders.push_back(extruder_support);
             else {
@@ -750,7 +1016,6 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
                     std::vector<float> flush_matrix(
                         cast<float>(get_flush_volumes_matrix(object.print()->config().flush_volumes_matrix.values, 0, object.print()->config().nozzle_diameter.values.size())));
                     const unsigned int number_of_extruders = (unsigned int) (sqrt(flush_matrix.size()) + EPSILON);
-                    // Extract purging volumes for each extruder pair:
                     std::vector<std::vector<float>> wipe_volumes;
                     for (unsigned int i = 0; i < number_of_extruders; ++i)
                         wipe_volumes.push_back(std::vector<float>(flush_matrix.begin() + i * number_of_extruders, flush_matrix.begin() + (i + 1) * number_of_extruders));
@@ -777,7 +1042,9 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
     }
 
     for (auto& layer : m_layer_tools) {
-        // Sort and remove duplicates
+        if (layer.preserve_extruder_order)
+            remove_duplicates_preserve_order(layer.extruders);
+        else
             sort_remove_duplicates(layer.extruders);
 
         // make sure that there are some tools for each object layer (e.g. tall wiping object will result in empty extruders vector)
@@ -1333,6 +1600,9 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
         &filament_sequences
     );
 
+    // TODO(fs-port): for layers with preserve_extruder_order=true the stats
+    // here reflect the optimized sequence; the guarded writeback below keeps
+    // the original ordering. UI-only divergence — see line ~1610 below.
     auto curr_flush_info = calc_filament_change_info_by_toolorder(print_config, filament_maps, nozzle_flush_mtx, filament_sequences);
     if (nozzle_nums <= 1)
         m_stats_by_single_extruder = curr_flush_info;
@@ -1374,9 +1644,20 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
         }
     }
 
-    for (size_t i = 0; i < filament_sequences.size(); ++i)
+    for (size_t i = 0; i < filament_sequences.size(); ++i) {
+        // FS preserve_extruder_order guard: keep the layer's existing extruder
+        // ordering by skipping writeback of the optimized sequence.
+        //
+        // Note: BP runs the optimizer (and updates stats) BEFORE this writeback
+        // because the optimizer is a free function in ToolOrderUtils.cpp without
+        // LayerTools access. Stats may diverge from g-code reality on
+        // preserve-order layers. See FS ToolOrdering.cpp:1156-1159 for the
+        // upstream behavior that guards earlier in the call chain.
+        if (m_layer_tools[i].preserve_extruder_order)
+            continue;
         m_layer_tools[i].extruders = std::move(filament_sequences[i]);
     }
+}
 // Layers are marked for infinite skirt aka draft shield. Not all the layers have to be printed.
 void ToolOrdering::mark_skirt_layers(const PrintConfig &config, coordf_t max_layer_height)
 {
@@ -1833,5 +2114,22 @@ int WipingExtrusions::get_support_interface_extruder_overrides(const PrintObject
     return -1;
 }
 
+// Resolve a 1-based filament ID through the mixed-filament manager.
+unsigned int ToolOrdering::resolve_mixed(unsigned int filament_id_1based,
+                                         int          layer_index,
+                                         float        layer_print_z,
+                                         float        layer_height) const
+{
+    return resolve_mixed_with_layer_heights(m_mixed_mgr,
+                                            m_num_physical,
+                                            filament_id_1based,
+                                            layer_index,
+                                            layer_print_z,
+                                            layer_height,
+                                            m_mixed_layer_height_a,
+                                            m_mixed_layer_height_b,
+                                            m_mixed_base_layer_height);
+}
+
 
 } // namespace Slic3r

src/libslic3r/GCode/ToolOrdering.hpp

@@ -4,6 +4,7 @@
 #define slic3r_ToolOrdering_hpp_
 
 #include "../libslic3r.h"
+#include "../MixedFilament.hpp"
 
 #include <utility>
 
@@ -145,14 +146,44 @@ public:
 	// Returns a zero based extruder this eec should be printed with, according to PrintRegion config or extruder_override if overriden.
 	unsigned int extruder(const ExtrusionEntityCollection &extrusions, const PrintRegion &region) const;
 
+    // Stub helpers for per-layer infill override (Task 14). Each returns
+    // the configured 1-based filament ID without per-layer logic until Task 14 lands.
+    unsigned int sparse_infill_filament_id_1based(const PrintRegion &region) const;
+    unsigned int infill_filament_id_1based(const PrintRegion &region) const;
+    bool         use_base_infill_filament(const PrintRegion &region) const;
+
     coordf_t 					print_z	= 0.;
     bool 						has_object = false;
     bool						has_support = false;
     // Zero based extruder IDs, ordered to minimize tool switches.
     std::vector<unsigned int> 	extruders;
+    // When set, downstream reorder passes leave this layer's extruder
+    // sequence in place (used by grouped manual mixed-filament patterns).
+    bool                        preserve_extruder_order = false;
     // If per layer extruder switches are inserted by the G-code preview slider, this value contains the new (1 based) extruder, with which the whole object layer is being printed with.
     // If not overriden, it is set to 0.
     unsigned int 				extruder_override = 0;
+    // Mixed-filament resolution context (set by ToolOrdering during collect_extruders).
+    const MixedFilamentManager *mixed_mgr    = nullptr;
+    size_t                      num_physical = 0;
+    // Sequential layer index (0-based), used by mixed-filament resolution.
+    int                         layer_index = -1;
+    // Total number of object layers for the current print object.
+    int                         object_layer_count = 0;
+    // Actual layer height for this print_z where available.
+    coordf_t                    layer_height = 0.;
+    // Optional mixed-layer cadence override from print settings.
+    float                       mixed_layer_height_a    = 0.f;
+    float                       mixed_layer_height_b    = 0.f;
+    float                       mixed_base_layer_height = 0.2f;
+
+    // Resolve a configured 1-based filament ID to a physical 1-based ID via the
+    // mixed-filament manager for this layer. Returns input unchanged if no manager
+    // is set or the ID is not a mixed slot.
+    bool is_mixed_slot_0based(unsigned int filament_id_0based) const {
+        return mixed_mgr && mixed_mgr->is_mixed(filament_id_0based + 1, num_physical);
+    }
+
     // Should a skirt be printed at this layer?
     // Layers are marked for infinite skirt aka draft shield. Not all the layers have to be printed.
     bool                        has_skirt = false;
@@ -172,6 +203,10 @@ public:
         return m_wiping_extrusions;
     }
 
+    // Resolve a 1-based filament ID through the mixed-filament manager for this layer.
+    // Returns input unchanged when mixed_mgr is null or ID is not a mixed slot.
+    unsigned int resolve_mixed_1based(unsigned int filament_id_1based) const;
+
 private:
     // This object holds list of extrusion that will be used for extruder wiping
     WipingExtrusions m_wiping_extrusions;
@@ -254,6 +289,14 @@ public:
 
     bool                has_non_support_filament(const PrintConfig &config);
 
+    // Resolve a 1-based filament ID through the mixed-filament manager.
+    // Returns the resolved physical extruder (1-based). If the ID is not a
+    // mixed filament or no manager is set, returns the input unchanged.
+    unsigned int resolve_mixed(unsigned int filament_id_1based,
+                               int          layer_index,
+                               float        layer_print_z = 0.f,
+                               float        layer_height  = 0.f) const;
+
 private:
     void				initialize_layers(std::vector<coordf_t> &zs);
     void 				collect_extruders(const PrintObject &object, const std::vector<std::pair<double, unsigned int>> &per_layer_extruder_switches);
@@ -262,6 +305,8 @@ private:
     void                mark_skirt_layers(const PrintConfig &config, coordf_t max_layer_height);
     void 				collect_extruder_statistics(bool prime_multi_material);
     void                reorder_extruders_for_minimum_flush_volume(bool reorder_first_layer);
+    // Read mixed_color_layer_height_a/b from config and cache in m_mixed_layer_height_*.
+    void                update_mixed_layer_height_settings();
 
     // BBS
     std::vector<unsigned int> generate_first_layer_tool_order(const Print& print);
@@ -278,6 +323,13 @@ private:
     const PrintConfig*         m_print_config_ptr = nullptr;
     const PrintObject*         m_print_object_ptr = nullptr;
     Print*                     m_print;
+    // Mixed filament support: pointer to manager (owned by Print) and
+    // number of physical extruders.
+    const MixedFilamentManager* m_mixed_mgr        = nullptr;
+    size_t                      m_num_physical      = 0;
+    float                       m_mixed_layer_height_a    = 0.f;
+    float                       m_mixed_layer_height_b    = 0.f;
+    float                       m_mixed_base_layer_height = 0.2f;
     bool                       m_sorted = false;
 
     FilamentChangeStats        m_stats_by_single_extruder;

src/libslic3r/GCode/WipeTower2.cpp

@@ -6,6 +6,7 @@
 #include <vector>
 #include <numeric>
 #include <memory>
+#include <limits>
 #include <sstream>
 #include <iomanip>
 
@@ -19,6 +20,7 @@
 #include "Fill/FillRectilinear.hpp"
 
 #include <boost/algorithm/string/predicate.hpp>
+#include <boost/log/trivial.hpp>
 
 
 namespace Slic3r
@@ -30,10 +32,16 @@ static const double     wipe_tower_wall_infill_overlap = 0.0;
 static constexpr double WIPE_TOWER_RESOLUTION          = 0.1;
 static constexpr double     WT_SIMPLIFY_TOLERANCE_SCALED   = 0.001f / SCALING_FACTOR_INTERNAL;
 static constexpr int    arc_fit_size                   = 20;
+static constexpr size_t LEGACY_NO_TOOL                 = static_cast<size_t>(std::numeric_limits<unsigned int>::max());
 #define SCALED_WIPE_TOWER_RESOLUTION (WIPE_TOWER_RESOLUTION / SCALING_FACTOR_INTERNAL)
 enum class LimitFlow { None, LimitPrintFlow, LimitRammingFlow };
 static const std::map<float, float> nozzle_diameter_to_nozzle_change_width{{0.2f, 0.5f}, {0.4f, 1.0f}, {0.6f, 1.2f}, {0.8f, 1.4f}};
 
+inline bool is_no_tool_sentinel(size_t tool)
+{
+    return tool == LEGACY_NO_TOOL || tool == size_t(-1);
+}
+
 inline float align_round(float value, float base) { return std::round(value / base) * base; }
 
 inline float align_ceil(float value, float base) { return std::ceil(value / base) * base; }
@@ -1257,6 +1265,7 @@ WipeTower2::WipeTower2(const PrintConfig& config, const PrintRegionConfig& defau
     m_extra_flow(float(config.wipe_tower_extra_flow/100.)),
     m_extra_spacing_wipe(float(config.wipe_tower_extra_spacing/100. * config.wipe_tower_extra_flow/100.)),
     m_extra_spacing_ramming(float(config.wipe_tower_extra_spacing/100.)),
+    m_local_z_wipe_tower_purge_lines(float(config.local_z_wipe_tower_purge_lines)),
     m_y_shift(0.f),
     m_z_pos(0.f),
     m_bridging(float(config.wipe_tower_bridging)),
@@ -1515,49 +1524,50 @@ std::vector<WipeTower::ToolChangeResult> WipeTower2::prime(
 	return results;
 }
 
-WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
+WipeTower::ToolChangeResult WipeTower2::emit_planned_tool_change(const WipeTowerInfo::ToolChange *tool_change)
 {
-    size_t old_tool = m_current_tool;
+    if (tool_change != nullptr && m_current_tool != tool_change->old_tool) {
+        BOOST_LOG_TRIVIAL(warning) << "Wipe tower tool state mismatch, realigning to planned toolchange"
+                                   << " layer_z=" << (m_layer_info != m_plan.end() ? m_layer_info->z : -1.f)
+                                   << " current_tool=" << m_current_tool
+                                   << " planned_old_tool=" << tool_change->old_tool
+                                   << " planned_new_tool=" << tool_change->new_tool;
+        m_current_tool = tool_change->old_tool;
+    }
+
+    const size_t tool     = tool_change != nullptr ? tool_change->new_tool : LEGACY_NO_TOOL;
+    const size_t old_tool = m_current_tool;
 
     float wipe_area   = 0.f;
     float wipe_volume = 0.f;
     bool  interface_layer = m_enable_tower_interface_features && m_current_layer_has_interface;
 
-	// Finds this toolchange info
-	if (tool != (unsigned int)(-1))
-	{
-		for (const auto &b : m_layer_info->tool_changes)
-			if ( b.new_tool == tool ) {
-                wipe_volume = b.wipe_volume;
-				wipe_area = b.required_depth;
-				break;
+    if (tool_change != nullptr) {
+        wipe_volume = tool_change->wipe_volume;
+        wipe_area   = tool_change->required_depth;
     }
-	}
-	else {
-		// Otherwise we are going to Unload only. And m_layer_info would be invalid.
-	}
-    if (interface_layer && tool != (unsigned int)(-1) && tool < m_filpar.size()) {
+    if (interface_layer && !is_no_tool_sentinel(tool) && tool < m_filpar.size()) {
         float extra_purge_length = m_filpar[tool].tower_interface_purge_length;
         if (extra_purge_length > 0.f) {
             wipe_volume += extra_purge_length * m_filpar[tool].filament_area;
         }
     }
 
-    WipeTower::box_coordinates cleaning_box(
-		Vec2f(m_perimeter_width / 2.f, m_perimeter_width / 2.f),
-		m_wipe_tower_width - m_perimeter_width,
-        (tool != (unsigned int)(-1) ? wipe_area+m_depth_traversed-0.5f*m_perimeter_width
-                                    : m_wipe_tower_depth-m_perimeter_width));
+    WipeTower::box_coordinates cleaning_box(Vec2f(m_perimeter_width / 2.f, m_perimeter_width / 2.f), m_wipe_tower_width - m_perimeter_width,
+                                            (!is_no_tool_sentinel(tool) ? wipe_area + m_depth_traversed - 0.5f * m_perimeter_width :
+                                                                          m_wipe_tower_depth - m_perimeter_width));
 
     WipeTowerWriter2 writer(m_layer_height, m_perimeter_width, m_gcode_flavor, m_filpar, m_enable_arc_fitting);
     writer.set_extrusion_flow(m_extrusion_flow)
         .set_z(m_z_pos)
         .set_initial_tool(m_current_tool)
-        .set_y_shift(m_y_shift + (tool!=(unsigned int)(-1) && (m_current_shape == SHAPE_REVERSED) ? m_layer_info->depth - m_layer_info->toolchanges_depth(): 0.f))
+        .set_y_shift(m_y_shift + (!is_no_tool_sentinel(tool) && (m_current_shape == SHAPE_REVERSED) ?
+                                      m_layer_info->depth - m_layer_info->toolchanges_depth() :
+                                      0.f))
         .append(";--------------------\n"
                 "; CP TOOLCHANGE START\n");
 
-    if (tool != (unsigned)(-1)){
+    if (!is_no_tool_sentinel(tool)) {
         writer.comment_with_value(" toolchange #", m_num_tool_changes + 1); // the number is zero-based
         writer.append(std::string("; material : " + (m_current_tool < m_filpar.size() ? m_filpar[m_current_tool].material : "(NONE)") + " -> " + m_filpar[tool].material + "\n").c_str())
             .append(";--------------------\n");
@@ -1574,8 +1584,10 @@ WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
 	if (m_set_extruder_trimpot)
 		writer.set_extruder_trimpot(750);
 
+    m_active_tool_change = tool_change;
+
     // Ram the hot material out of the melt zone, retract the filament into the cooling tubes and let it cool.
-    if (tool != (unsigned int)-1){ 			// This is not the last change.
+    if (!is_no_tool_sentinel(tool)) { // This is not the last change.
         auto new_tool_temp = is_first_layer() ? m_filpar[tool].first_layer_temperature : m_filpar[tool].temperature;
         toolchange_Unload(writer, cleaning_box, m_filpar[m_current_tool].material,
                           (is_first_layer() ? m_filpar[m_current_tool].first_layer_temperature : m_filpar[m_current_tool].temperature),
@@ -1609,6 +1621,7 @@ WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
     } else
         toolchange_Unload(writer, cleaning_box, m_filpar[m_current_tool].material, m_filpar[m_current_tool].temperature, m_filpar[m_current_tool].temperature);
 
+    m_active_tool_change = nullptr;
     m_depth_traversed += wipe_area;
 
 	if (m_set_extruder_trimpot)
@@ -1625,7 +1638,46 @@ WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
     if (m_current_tool < m_used_filament_length.size())
         m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
 
-    return construct_tcr(writer, false, old_tool, false, interface_layer);
+    WipeTower::ToolChangeResult result = construct_tcr(writer, false, old_tool, false, interface_layer);
+    result.purge_volume                = wipe_volume;
+    return result;
+}
+
+WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
+{
+    const WipeTowerInfo::ToolChange *planned_tool_change = nullptr;
+    if (!is_no_tool_sentinel(tool)) {
+        for (const WipeTowerInfo::ToolChange &entry : m_layer_info->tool_changes) {
+            if (entry.old_tool == m_current_tool && entry.new_tool == tool) {
+                planned_tool_change = &entry;
+                break;
+            }
+        }
+        if (planned_tool_change == nullptr) {
+            for (const WipeTowerInfo::ToolChange &entry : m_layer_info->tool_changes) {
+                if (entry.new_tool == tool) {
+                    planned_tool_change = &entry;
+                    break;
+                }
+            }
+        }
+        if (planned_tool_change == nullptr) {
+            std::ostringstream planned_sequence;
+            for (size_t idx = 0; idx < m_layer_info->tool_changes.size(); ++idx) {
+                if (idx != 0)
+                    planned_sequence << ",";
+                planned_sequence << m_layer_info->tool_changes[idx].old_tool << "->" << m_layer_info->tool_changes[idx].new_tool;
+            }
+            BOOST_LOG_TRIVIAL(error) << "Wipe tower toolchange not found in plan"
+                                     << " layer_z=" << (m_layer_info != m_plan.end() ? m_layer_info->z : -1.f)
+                                     << " current_tool=" << m_current_tool
+                                     << " requested_new_tool=" << tool
+                                     << " planned_sequence=[" << planned_sequence.str() << "]";
+            throw Slic3r::RuntimeError("Wipe tower toolchange not found in plan.");
+        }
+    }
+
+    return emit_planned_tool_change(planned_tool_change);
 }
 
 
@@ -1678,22 +1730,15 @@ void WipeTower2::toolchange_Unload(
         else
             sparse_beginning_y += (m_layer_info-1)->toolchanges_depth() + m_perimeter_width;
 
-        float sum_of_depths = 0.f;
-        for (const auto& tch : m_layer_info->tool_changes) {  // let's find this toolchange
-            if (tch.old_tool == m_current_tool) {
-                sum_of_depths += tch.ramming_depth;
-                float ramming_end_y = sum_of_depths;
+        if (m_active_tool_change != nullptr) {
+            float ramming_end_y = cumulative_toolchange_depth_before(m_active_tool_change) + m_active_tool_change->ramming_depth;
             ramming_end_y -= (y_step / m_extra_spacing_ramming - m_perimeter_width) / 2.f; // center of final ramming line
 
             if ((m_current_shape == SHAPE_REVERSED && ramming_end_y < sparse_beginning_y - 0.5f * m_perimeter_width) ||
-                     (m_current_shape == SHAPE_NORMAL && ramming_end_y > sparse_beginning_y + 0.5f*m_perimeter_width  )  )
-                {
-                    writer.extrude(xl + tch.first_wipe_line-1.f*m_perimeter_width,writer.y());
-                    remaining -= tch.first_wipe_line-1.f*m_perimeter_width;
+                (m_current_shape == SHAPE_NORMAL && ramming_end_y > sparse_beginning_y + 0.5f * m_perimeter_width)) {
+                writer.extrude(xl + m_active_tool_change->first_wipe_line - 1.f * m_perimeter_width, writer.y());
+                remaining -= m_active_tool_change->first_wipe_line - 1.f * m_perimeter_width;
             }
-                break;
-            }
-            sum_of_depths += tch.required_depth;
         }
     }
 
@@ -1989,8 +2034,16 @@ void WipeTower2::toolchange_Wipe(
           .add_wipe_point(writer.x(), writer.y() - dy)
           .add_wipe_point(! m_left_to_right ? m_wipe_tower_width : 0.f, writer.y() - dy);
 
-    if (m_layer_info != m_plan.end() && m_current_tool != m_layer_info->tool_changes.back().new_tool)
+    if (m_layer_info != m_plan.end()) {
+        size_t final_tool_on_layer = m_current_tool;
+        if (!m_layer_info->tool_changes.empty())
+            final_tool_on_layer = m_layer_info->tool_changes.back().new_tool;
+        else if (!m_layer_info->local_z_tool_changes.empty())
+            final_tool_on_layer = m_layer_info->local_z_tool_changes.back().new_tool;
+
+        if (m_current_tool != final_tool_on_layer)
             m_left_to_right = !m_left_to_right;
+    }
 
     writer.set_extrusion_flow(m_extrusion_flow); // Reset the extrusion flow.
     writer.change_analyzer_line_width(m_perimeter_width);
@@ -2019,7 +2072,8 @@ WipeTower::ToolChangeResult WipeTower2::finish_layer()
     float                      feedrate      = first_layer ? m_first_layer_speed * 60.f : std::min(m_wipe_tower_max_purge_speed * 60.f, m_infill_speed * 60.f);
     if (m_enable_tower_interface_features && m_prev_layer_had_interface)
         feedrate = std::min(feedrate, 20.f * 60.f);
-    float current_depth = m_layer_info->depth - m_layer_info->toolchanges_depth();
+    float reserve_depth = m_layer_info->local_z_reserve_depth();
+    float current_depth = std::max(0.f, m_layer_info->depth - m_layer_info->toolchanges_depth() - reserve_depth);
     WipeTower::box_coordinates fill_box(Vec2f(m_perimeter_width, m_layer_info->depth-(current_depth-m_perimeter_width)),
                              m_wipe_tower_width - 2 * m_perimeter_width, current_depth-m_perimeter_width);
 
@@ -2050,14 +2104,7 @@ WipeTower::ToolChangeResult WipeTower2::finish_layer()
 
         // Is there a soluble filament wiped/rammed at the next layer?
         // If so, the infill should not be sparse.
-        bool solid_infill = m_layer_info+1 == m_plan.end()
-                          ? false
-                          : std::any_of((m_layer_info+1)->tool_changes.begin(),
-                                        (m_layer_info+1)->tool_changes.end(),
-                                            [this](const WipeTowerInfo::ToolChange& tch) {
-                                       return m_filpar[tch.new_tool].is_soluble
-                                           || m_filpar[tch.old_tool].is_soluble;
-                                            });
+        bool solid_infill = m_layer_info + 1 == m_plan.end() ? false : layer_has_soluble_toolchange(*(m_layer_info + 1));
         solid_infill |= first_layer && m_adhesion;
 
         if (solid_infill) {
@@ -2249,6 +2296,205 @@ void WipeTower2::plan_toolchange(float z_par, float layer_height_par, unsigned i
 	m_plan.back().tool_changes.push_back(WipeTowerInfo::ToolChange(old_tool, new_tool, ramming_depth + wiping_depth, ramming_depth, first_wipe_line, wipe_volume));
 }
 
+void WipeTower2::plan_local_z_toolchange(float z_par, float layer_height_par, unsigned int old_tool, unsigned int new_tool, float wipe_volume)
+{
+    assert(m_plan.empty() || m_plan.back().z <= z_par + WT_EPSILON);
+
+    if (m_plan.empty() || m_plan.back().z + WT_EPSILON < z_par)
+        m_plan.push_back(WipeTowerInfo(z_par, layer_height_par));
+
+    if (m_first_layer_idx == size_t(-1) && (!m_no_sparse_layers || old_tool != new_tool || m_plan.size() == 1))
+        m_first_layer_idx = m_plan.size() - 1;
+
+    if (old_tool == new_tool)
+        return;
+
+    float width             = m_wipe_tower_width - 3 * m_perimeter_width;
+    float length_to_extrude = volume_to_length(0.25f * std::accumulate(m_filpar[old_tool].ramming_speed.begin(),
+                                                                       m_filpar[old_tool].ramming_speed.end(), 0.f),
+                                               m_perimeter_width * m_filpar[old_tool].ramming_line_width_multiplicator, layer_height_par);
+    float ramming_depth     = m_enable_filament_ramming ? ((int(length_to_extrude / width) + 1) *
+                                                       (m_perimeter_width * m_filpar[old_tool].ramming_line_width_multiplicator *
+                                                        m_filpar[old_tool].ramming_step_multiplicator) *
+                                                       m_extra_spacing_ramming) :
+                                                        0;
+    float first_wipe_line   = -(width * ((length_to_extrude / width) - int(length_to_extrude / width)) - width);
+
+    float first_wipe_volume = length_to_volume(first_wipe_line, m_perimeter_width * m_extra_flow, layer_height_par);
+    float wiping_depth      = get_wipe_depth(wipe_volume - first_wipe_volume, layer_height_par, m_perimeter_width, m_extra_flow,
+                                             m_extra_spacing_wipe, width);
+
+    m_plan.back().local_z_tool_changes.push_back(
+        WipeTowerInfo::ToolChange(old_tool, new_tool, ramming_depth + wiping_depth, ramming_depth, first_wipe_line, wipe_volume));
+}
+
+void WipeTower2::plan_local_z_reserve(float z_par, float layer_height_par, size_t reserve_slot_count, float wipe_volume)
+{
+    if (reserve_slot_count == 0)
+        return;
+
+    assert(m_plan.empty() || m_plan.back().z <= z_par + WT_EPSILON);
+
+    if (m_plan.empty() || m_plan.back().z + WT_EPSILON < z_par)
+        m_plan.push_back(WipeTowerInfo(z_par, layer_height_par));
+
+    const float mini_wipe_depth = m_local_z_wipe_tower_purge_lines * m_perimeter_width * m_extra_spacing_wipe;
+    const float wipe_width      = std::max(0.f, m_wipe_tower_width - 3.f * m_perimeter_width);
+    const float wiping_depth    = wipe_width > WT_EPSILON ?
+                                      get_wipe_depth(std::max(0.f, wipe_volume), layer_height_par, m_perimeter_width, m_extra_flow,
+                                                     m_extra_spacing_wipe, wipe_width) :
+                                      0.f;
+
+    float max_ramming_depth = 0.f;
+    if (wipe_width > WT_EPSILON) {
+        for (const FilamentParameters& filament : m_filpar) {
+            const bool do_ramming = (m_semm && m_enable_filament_ramming) || filament.multitool_ramming;
+            if (!do_ramming || filament.ramming_speed.empty())
+                continue;
+
+            const float line_width = m_perimeter_width * filament.ramming_line_width_multiplicator;
+            const float line_step =
+                (m_perimeter_width * filament.ramming_line_width_multiplicator * filament.ramming_step_multiplicator) *
+                m_extra_spacing_ramming;
+            if (line_width <= WT_EPSILON || line_step <= WT_EPSILON)
+                continue;
+
+            const float ramming_volume = 0.25f * std::accumulate(filament.ramming_speed.begin(), filament.ramming_speed.end(), 0.f);
+            const float length_to_extrude = volume_to_length(ramming_volume, line_width, layer_height_par);
+            const float ramming_depth =
+                (float(int(length_to_extrude / wipe_width) + 1) * line_step);
+            max_ramming_depth = std::max(max_ramming_depth, ramming_depth);
+        }
+    }
+
+    const float full_toolchange_depth = max_ramming_depth + wiping_depth;
+    const float slot_depth =
+        std::max(2.5f * m_perimeter_width, std::max(mini_wipe_depth + m_perimeter_width, full_toolchange_depth + m_perimeter_width));
+
+    WipeTowerInfo &layer = m_plan.back();
+    layer.local_z_reserve_slot_depth = std::max(layer.local_z_reserve_slot_depth, slot_depth);
+    layer.local_z_reserve_slot_count += reserve_slot_count;
+}
+
+WipeTower::ToolChangeResult WipeTower2::local_z_tool_change(size_t new_tool,
+                                                            const WipeTower::box_coordinates& cleaning_box,
+                                                            float wipe_volume)
+{
+    const size_t old_tool = m_current_tool;
+
+    WipeTowerWriter2 writer(m_layer_height, m_perimeter_width, m_gcode_flavor, m_filpar, m_enable_arc_fitting);
+    writer.set_extrusion_flow(m_extrusion_flow)
+        .set_z(m_z_pos)
+        .set_initial_tool(m_current_tool)
+        .append(";--------------------\n"
+                "; CP TOOLCHANGE START\n");
+
+    writer.comment_with_value(" toolchange #", m_num_tool_changes + 1);
+    writer.append(std::string("; material : " + (m_current_tool < m_filpar.size() ? m_filpar[m_current_tool].material : "(NONE)") + " -> " +
+                              m_filpar[new_tool].material + "\n")
+                      .c_str())
+        .append(";--------------------\n");
+    writer.append(";" + GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Wipe_Tower_Start) + "\n");
+
+    writer.speed_override_backup();
+    writer.speed_override(100);
+    writer.set_initial_position(cleaning_box.ld, m_wipe_tower_width, m_wipe_tower_depth, 0.f);
+
+    if (m_set_extruder_trimpot)
+        writer.set_extruder_trimpot(750);
+
+    const int old_tool_temp = is_first_layer() ? m_filpar[m_current_tool].first_layer_temperature : m_filpar[m_current_tool].temperature;
+    const int new_tool_temp = is_first_layer() ? m_filpar[new_tool].first_layer_temperature : m_filpar[new_tool].temperature;
+
+    toolchange_Unload(writer, cleaning_box, m_filpar[m_current_tool].material, old_tool_temp, new_tool_temp);
+    toolchange_Change(writer, new_tool, m_filpar[new_tool].material);
+    toolchange_Load(writer, cleaning_box);
+    writer.travel(writer.x(), writer.y() - m_perimeter_width);
+    toolchange_Wipe(writer, cleaning_box, wipe_volume, false);
+    writer.append(";" + GCodeProcessor::reserved_tag(GCodeProcessor::ETags::Wipe_Tower_End) + "\n");
+
+    ++m_num_tool_changes;
+
+    if (m_set_extruder_trimpot)
+        writer.set_extruder_trimpot(550);
+    writer.speed_override_restore();
+    writer.feedrate(m_travel_speed * 60.f)
+        .flush_planner_queue()
+        .reset_extruder()
+        .append("; CP TOOLCHANGE END\n"
+                ";------------------\n"
+                "\n\n");
+
+    if (m_current_tool < m_used_filament_length.size())
+        m_used_filament_length[m_current_tool] += writer.get_and_reset_used_filament_length();
+
+    WipeTower::ToolChangeResult result = construct_tcr(writer, false, old_tool, false);
+    result.purge_volume                = wipe_volume;
+    return result;
+}
+
+namespace {
+// Helper: rotate a point within the wipe tower local coordinate system
+// by internal_angle_deg, shifting by y_shift.
+static Vec2f rotate_local_z_reserve_point(const Vec2f& pt, float tower_width, float tower_depth,
+                                           float y_shift, float internal_angle_deg)
+{
+    Vec2f shifted = pt;
+    shifted.x() -= tower_width / 2.f;
+    shifted.y() += y_shift - tower_depth / 2.f;
+    const double angle = internal_angle_deg * double(M_PI / 180.);
+    const double c     = std::cos(angle);
+    const double s     = std::sin(angle);
+    return Vec2f(float(shifted.x() * c - shifted.y() * s) + tower_width / 2.f,
+                 float(shifted.x() * s + shifted.y() * c) + tower_depth / 2.f);
+}
+} // namespace
+
+std::vector<std::vector<WipeTower::box_coordinates>> WipeTower2::get_local_z_reserve_boxes() const
+{
+    std::vector<std::vector<WipeTower::box_coordinates>> out;
+    out.reserve(m_plan.size());
+
+    for (size_t layer_idx = 0; layer_idx < m_plan.size(); ++layer_idx) {
+        const WipeTowerInfo& layer = m_plan[layer_idx];
+        std::vector<WipeTower::box_coordinates> layer_boxes;
+        layer_boxes.reserve(layer.local_z_reserve_slot_count);
+
+        if (layer.local_z_reserve_slot_count > 0 && layer.local_z_reserve_slot_depth > WT_EPSILON) {
+            const float y_shift = layer.depth < m_wipe_tower_depth - m_perimeter_width ?
+                (m_wipe_tower_depth - layer.depth - m_perimeter_width) / 2.f : 0.f;
+            const float internal_angle = (layer_idx % 2 == 0) ? 180.f : 0.f;
+
+            for (size_t slot_idx = 0; slot_idx < layer.local_z_reserve_slot_count; ++slot_idx) {
+                const float slot_start = layer.toolchanges_depth() + float(slot_idx) * layer.local_z_reserve_slot_depth;
+                const float width      = std::max(0.f, m_wipe_tower_width - 2.f * m_perimeter_width);
+                const float height     = std::max(0.f, layer.local_z_reserve_slot_depth - m_perimeter_width);
+                if (width <= WT_EPSILON || height <= WT_EPSILON)
+                    continue;
+
+                const Vec2f ld_unrotated(m_perimeter_width, slot_start + m_perimeter_width);
+                const Vec2f rd_unrotated = ld_unrotated + Vec2f(width, 0.f);
+                const Vec2f ru_unrotated = ld_unrotated + Vec2f(width, height);
+                const Vec2f lu_unrotated = ld_unrotated + Vec2f(0.f, height);
+
+                const Vec2f ld = rotate_local_z_reserve_point(ld_unrotated, m_wipe_tower_width, m_wipe_tower_depth, y_shift, internal_angle);
+                const Vec2f rd = rotate_local_z_reserve_point(rd_unrotated, m_wipe_tower_width, m_wipe_tower_depth, y_shift, internal_angle);
+                const Vec2f ru = rotate_local_z_reserve_point(ru_unrotated, m_wipe_tower_width, m_wipe_tower_depth, y_shift, internal_angle);
+                const Vec2f lu = rotate_local_z_reserve_point(lu_unrotated, m_wipe_tower_width, m_wipe_tower_depth, y_shift, internal_angle);
+
+                const float min_x = std::min({ld.x(), rd.x(), ru.x(), lu.x()});
+                const float max_x = std::max({ld.x(), rd.x(), ru.x(), lu.x()});
+                const float min_y = std::min({ld.y(), rd.y(), ru.y(), lu.y()});
+                const float max_y = std::max({ld.y(), rd.y(), ru.y(), lu.y()});
+                layer_boxes.emplace_back(Vec2f(min_x, min_y), max_x - min_x, max_y - min_y);
+            }
+        }
+
+        out.emplace_back(std::move(layer_boxes));
+    }
+
+    return out;
+}
 
 
 void WipeTower2::plan_tower()
@@ -2262,7 +2508,7 @@ void WipeTower2::plan_tower()
 	
     for (int layer_index = int(m_plan.size()) - 1; layer_index >= 0; --layer_index)
 	{
-		float this_layer_depth = std::max(m_plan[layer_index].depth, m_plan[layer_index].toolchanges_depth());
+		float this_layer_depth = std::max(m_plan[layer_index].depth, m_plan[layer_index].planned_depth());
 		m_plan[layer_index].depth = this_layer_depth;
 		
 		if (this_layer_depth > m_wipe_tower_depth - m_perimeter_width)
@@ -2293,7 +2539,7 @@ void WipeTower2::save_on_last_wipe()
 
         for (int i=0; i<int(m_layer_info->tool_changes.size()); ++i) {
             auto& toolchange = m_layer_info->tool_changes[i];
-            tool_change(toolchange.new_tool);
+            emit_planned_tool_change(&toolchange);
 
             if (i == idx) {
                 float width = m_wipe_tower_width - 3*m_perimeter_width; // width we draw into
@@ -2339,8 +2585,38 @@ int WipeTower2::first_toolchange_to_nonsoluble(
     return tool_changes.empty() ? -1 : 0;
 }
 
-static WipeTower::ToolChangeResult merge_tcr(WipeTower::ToolChangeResult& first,
-                                             WipeTower::ToolChangeResult& second)
+bool WipeTower2::layer_has_soluble_toolchange(const WipeTowerInfo &layer) const
+{
+    auto has_soluble = [this](const std::vector<WipeTowerInfo::ToolChange> &tool_changes) {
+        return std::any_of(tool_changes.begin(), tool_changes.end(), [this](const WipeTowerInfo::ToolChange &toolchange) {
+            return m_filpar[toolchange.new_tool].is_soluble || m_filpar[toolchange.old_tool].is_soluble;
+        });
+    };
+
+    return has_soluble(layer.local_z_tool_changes) || has_soluble(layer.tool_changes);
+}
+
+float WipeTower2::cumulative_toolchange_depth_before(const WipeTowerInfo::ToolChange *tool_change) const
+{
+    if (tool_change == nullptr || m_layer_info == m_plan.end())
+        return 0.f;
+
+    float depth = 0.f;
+    for (const WipeTowerInfo::ToolChange &entry : m_layer_info->local_z_tool_changes) {
+        if (&entry == tool_change)
+            return depth;
+        depth += entry.required_depth;
+    }
+    for (const WipeTowerInfo::ToolChange &entry : m_layer_info->tool_changes) {
+        if (&entry == tool_change)
+            return depth;
+        depth += entry.required_depth;
+    }
+
+    return depth;
+}
+
+static WipeTower::ToolChangeResult merge_tcr(WipeTower::ToolChangeResult& first, WipeTower::ToolChangeResult& second)
 {
     assert(first.new_tool == second.initial_tool);
     WipeTower::ToolChangeResult out = first;
@@ -2358,10 +2634,11 @@ static WipeTower::ToolChangeResult merge_tcr(WipeTower::ToolChangeResult& first,
     return out;
 }
 
-
-// Processes vector m_plan and calls respective functions to generate G-code for the wipe tower
-// Resulting ToolChangeResults are appended into vector "result"
-void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>> &result)
+// Processes vector m_plan and calls respective functions to generate G-code for the wipe tower.
+// Normal per-layer toolchanges are appended into "result", while Local-Z phase-b toolchanges are
+// emitted into "local_z_result" so G-code can consume them before the nominal layer loop.
+void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>& result,
+                          std::vector<std::vector<WipeTower::ToolChangeResult>>& local_z_result)
 {
 	if (m_plan.empty())
         return;
@@ -2383,8 +2660,12 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
     m_layer_info = m_plan.begin();
     m_current_height = 0.f;
 
-    // we don't know which extruder to start with - we'll set it according to the first toolchange
+    // We don't know which extruder to start with, so take the first actual toolchange on the tower.
     for (const auto& layer : m_plan) {
+        if (!layer.local_z_tool_changes.empty()) {
+            m_current_tool = layer.local_z_tool_changes.front().old_tool;
+            break;
+        }
         if (!layer.tool_changes.empty()) {
             m_current_tool = layer.tool_changes.front().old_tool;
             break;
@@ -2400,6 +2681,14 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
 	for (const WipeTower2::WipeTowerInfo& layer : m_plan)
 	{
         std::vector<WipeTower::ToolChangeResult> layer_result;
+        std::vector<WipeTower::ToolChangeResult> local_z_layer_result;
+        BOOST_LOG_TRIVIAL(debug) << "Wipe tower layer plan"
+                                 << " z=" << layer.z
+                                 << " height=" << layer.height
+                                 << " nominal_toolchanges=" << layer.tool_changes.size()
+                                 << " local_z_toolchanges=" << layer.local_z_tool_changes.size()
+                                 << " reserve_slots=" << layer.local_z_reserve_slot_count
+                                 << " planned_depth=" << layer.planned_depth();
         set_layer(layer.z, layer.height, 0, false /*layer.z == m_plan.front().z*/, layer.z == m_plan.back().z);
         m_internal_rotation += 180.f;
 
@@ -2409,15 +2698,18 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
         int idx = first_toolchange_to_nonsoluble(layer.tool_changes);
         WipeTower::ToolChangeResult finish_layer_tcr;
 
+        for (const WipeTowerInfo::ToolChange &toolchange : layer.local_z_tool_changes)
+            local_z_layer_result.emplace_back(emit_planned_tool_change(&toolchange));
+
         if (idx == -1) {
-            // if there is no toolchange switching to non-soluble, finish layer
-            // will be called at the very beginning. That's the last possibility
-            // where a nonsoluble tool can be.
+            // If there is no nominal-layer toolchange switching to non-soluble,
+            // finish_layer still runs after any Local-Z toolchanges already planned
+            // onto this tower layer.
             finish_layer_tcr = finish_layer();
         }
 
         for (int i = 0; i < int(layer.tool_changes.size()); ++i) {
-            layer_result.emplace_back(tool_change(layer.tool_changes[i].new_tool));
+            layer_result.emplace_back(emit_planned_tool_change(&layer.tool_changes[i]));
             if (i == idx) // finish_layer will be called after this toolchange
                 finish_layer_tcr = finish_layer();
         }
@@ -2436,6 +2728,7 @@ void WipeTower2::generate(std::vector<std::vector<WipeTower::ToolChangeResult>>
         }
 
         result.emplace_back(std::move(layer_result));
+        local_z_result.emplace_back(std::move(local_z_layer_result));
 
         if (m_used_filament_length_until_layer.empty() || m_used_filament_length_until_layer.back().first != layer.z)
             m_used_filament_length_until_layer.emplace_back();

src/libslic3r/GCode/WipeTower2.hpp

@@ -51,12 +51,17 @@ public:
 	// Appends into internal structure m_plan containing info about the future wipe tower
 	// to be used before building begins. The entries must be added ordered in z.
     void plan_toolchange(float z_par, float layer_height_par, unsigned int old_tool, unsigned int new_tool, float wipe_volume = 0.f);
+    void plan_local_z_toolchange(float z_par, float layer_height_par, unsigned int old_tool, unsigned int new_tool, float wipe_volume = 0.f);
+    // Reserve Local-Z wipe-tower slots for unplanned toolchanges during Local-Z sub-layer emission.
+    void plan_local_z_reserve(float z_par, float layer_height_par, size_t reserve_slot_count, float wipe_volume = 0.f);
 
 	// Iterates through prepared m_plan, generates ToolChangeResults and appends them to "result"
-	void generate(std::vector<std::vector<WipeTower::ToolChangeResult>> &result);
+	void generate(std::vector<std::vector<WipeTower::ToolChangeResult>> &result,
+                  std::vector<std::vector<WipeTower::ToolChangeResult>> &local_z_result);
 
     float get_depth() const { return m_wipe_tower_depth; }
 	std::vector<std::pair<float, float>> get_z_and_depth_pairs() const;
+    std::vector<std::vector<WipeTower::box_coordinates>> get_local_z_reserve_boxes() const;
     float get_brim_width() const { return m_wipe_tower_brim_width_real; }
 	float get_wipe_tower_height() const { return m_wipe_tower_height; }
     // ORCA: Match WipeTower API used by Print skirt/brim planning.
@@ -132,6 +137,9 @@ public:
 	// Returns gcode for a toolchange and a final print head position.
 	// On the first layer, extrude a brim around the future wipe tower first.
     WipeTower::ToolChangeResult tool_change(size_t new_tool);
+    // Emit a mini toolchange into a pre-reserved Local-Z wipe slot (does not consume m_plan).
+    WipeTower::ToolChangeResult local_z_tool_change(size_t new_tool, const WipeTower::box_coordinates& cleaning_box, float wipe_volume);
+    void set_current_tool(size_t tool) { m_current_tool = tool; }
 
 	// Fill the unfilled space with a sparse infill.
 	// Call this method only if layer_finished() is false.
@@ -182,6 +190,8 @@ public:
     };
 
 private:
+    struct WipeTowerInfo;
+
 	enum wipe_shape // A fill-in direction
 	{
 		SHAPE_NORMAL = 1,
@@ -260,6 +270,9 @@ private:
 	// Extruder specific parameters.
     std::vector<FilamentParameters> m_filpar;
 
+    // Number of wipe-tower purge lines to reserve per Local-Z unplanned toolchange slot.
+    float m_local_z_wipe_tower_purge_lines = 3.f;
+
 	// State of the wipe tower generator.
 	unsigned int m_num_layer_changes = 0; // Layer change counter for the output statistics.
 	unsigned int m_num_tool_changes  = 0; // Tool change change counter for the output statistics.
@@ -309,9 +322,16 @@ private:
 		float z;		// z position of the layer
 		float height;	// layer height
 		float depth;	// depth of the layer based on all layers above
-		float toolchanges_depth() const { float sum = 0.f; for (const auto &a : tool_changes) sum += a.required_depth; return sum; }
+        float normal_toolchanges_depth() const { float sum = 0.f; for (const auto &a : tool_changes) sum += a.required_depth; return sum; }
+        float local_z_toolchanges_depth() const { float sum = 0.f; for (const auto &a : local_z_tool_changes) sum += a.required_depth; return sum; }
+		float toolchanges_depth() const { return normal_toolchanges_depth() + local_z_toolchanges_depth(); }
+        float local_z_reserve_slot_depth { 0.f };
+        size_t local_z_reserve_slot_count { 0 };
+        float local_z_reserve_depth() const { return local_z_reserve_slot_depth * float(local_z_reserve_slot_count); }
+        float planned_depth() const { return toolchanges_depth() + local_z_reserve_depth(); }
 
 		std::vector<ToolChange> tool_changes;
+        std::vector<ToolChange> local_z_tool_changes;
 
 		WipeTowerInfo(float z_par, float layer_height_par)
 			: z{z_par}, height{layer_height_par}, depth{0} {}
@@ -319,6 +339,7 @@ private:
 
 	std::vector<WipeTowerInfo> m_plan; 	// Stores information about all layers and toolchanges for the future wipe tower (filled by plan_toolchange(...))
 	std::vector<WipeTowerInfo>::iterator m_layer_info = m_plan.end();
+    const WipeTowerInfo::ToolChange     *m_active_tool_change = nullptr;
 
 	// This sums height of all extruded layers, not counting the layers which
 	// will be later removed when the "no_sparse_layers" is used.
@@ -332,6 +353,9 @@ private:
     // ot -1 if there is no such toolchange.
     int first_toolchange_to_nonsoluble(
             const std::vector<WipeTowerInfo::ToolChange>& tool_changes) const;
+    bool layer_has_soluble_toolchange(const WipeTowerInfo &layer) const;
+    float cumulative_toolchange_depth_before(const WipeTowerInfo::ToolChange *tool_change) const;
+    WipeTower::ToolChangeResult emit_planned_tool_change(const WipeTowerInfo::ToolChange *tool_change);
 
 	void toolchange_Unload(
 		WipeTowerWriter2 &writer,

src/libslic3r/LocalZOrderOptimizer.hpp

@@ -0,0 +1,72 @@
+#ifndef slic3r_LocalZOrderOptimizer_hpp_
+#define slic3r_LocalZOrderOptimizer_hpp_
+
+#include <algorithm>
+#include <numeric>
+#include <vector>
+
+namespace Slic3r {
+namespace LocalZOrderOptimizer {
+
+inline bool bucket_contains_extruder(const std::vector<unsigned int> &extruders, int extruder_id)
+{
+    return extruder_id >= 0 &&
+           std::find(extruders.begin(), extruders.end(), static_cast<unsigned int>(extruder_id)) != extruders.end();
+}
+
+inline std::vector<unsigned int> order_bucket_extruders(std::vector<unsigned int> extruders,
+                                                        int                       current_extruder,
+                                                        int                       preferred_last_extruder = -1)
+{
+    extruders.erase(std::unique(extruders.begin(), extruders.end()), extruders.end());
+    if (extruders.empty())
+        return extruders;
+
+    if (current_extruder >= 0) {
+        auto current_it = std::find(extruders.begin(), extruders.end(), static_cast<unsigned int>(current_extruder));
+        if (current_it != extruders.end())
+            std::rotate(extruders.begin(), current_it, extruders.end());
+    }
+
+    if (preferred_last_extruder >= 0 && extruders.size() > 1 && static_cast<int>(extruders.front()) != preferred_last_extruder) {
+        auto preferred_it = std::find(extruders.begin() + 1, extruders.end(), static_cast<unsigned int>(preferred_last_extruder));
+        if (preferred_it != extruders.end())
+            std::rotate(preferred_it, preferred_it + 1, extruders.end());
+    }
+
+    return extruders;
+}
+
+inline std::vector<size_t> order_pass_group(const std::vector<std::vector<unsigned int>> &group_extruders, int current_extruder)
+{
+    std::vector<size_t> remaining(group_extruders.size());
+    std::iota(remaining.begin(), remaining.end(), size_t(0));
+
+    std::vector<size_t> ordered;
+    ordered.reserve(group_extruders.size());
+
+    int active_extruder = current_extruder;
+    while (!remaining.empty()) {
+        auto next_it = std::find_if(remaining.begin(), remaining.end(), [&](size_t idx) {
+            return bucket_contains_extruder(group_extruders[idx], active_extruder);
+        });
+        if (next_it == remaining.end())
+            next_it = remaining.begin();
+
+        const size_t next_idx = *next_it;
+        ordered.push_back(next_idx);
+
+        const std::vector<unsigned int> ordered_bucket = order_bucket_extruders(group_extruders[next_idx], active_extruder);
+        if (!ordered_bucket.empty())
+            active_extruder = static_cast<int>(ordered_bucket.back());
+
+        remaining.erase(next_it);
+    }
+
+    return ordered;
+}
+
+} // namespace LocalZOrderOptimizer
+} // namespace Slic3r
+
+#endif

src/libslic3r/MixedFilament.hpp

@@ -0,0 +1,317 @@
+#ifndef slic3r_MixedFilament_hpp_
+#define slic3r_MixedFilament_hpp_
+
+#include <string>
+#include <vector>
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+#include <utility>
+
+namespace Slic3r {
+
+// Represents a virtual "mixed" filament created from physical filaments
+// (layer cadence and/or same-layer interleaved stripe distribution). Display
+// colour blending uses FilamentMixer  so pair previews better
+//  match expected print mixing 
+// (for example Blue+Yellow -> Green, Red+Yellow -> Orange, Red+Blue -> Purple). 
+// Legacy RYB code is retained in source for reference only.
+struct MixedFilament
+{
+    enum DistributionMode : uint8_t {
+        LayerCycle = 0,
+        SameLayerPointillisme = 1,
+        Simple = 2
+    };
+
+    // 1-based physical filament IDs that are combined.
+    unsigned int component_a = 1;
+    unsigned int component_b = 2;
+
+    // Persistent row identity used to keep painted virtual-tool assignments
+    // stable even when the visible mixed-filament list is rebuilt.
+    uint64_t stable_id = 0;
+
+    // Layer-alternation ratio.  With ratio_a = 2, ratio_b = 1 the cycle is
+    // A, A, B, A, A, B, ...
+    int ratio_a = 1;
+    int ratio_b = 1;
+
+    // Blend percentage of component B in [0..100].
+    int mix_b_percent = 50;
+
+    // Optional manual pattern for this mixed filament. Tokens:
+    // '1' => component_a, '2' => component_b, '3'..'9' => direct physical
+    // filament IDs (1-based). Example: "11112222" => AAAABBBB repeating.
+    std::string manual_pattern;
+
+    // Optional explicit gradient multi-color component list, encoded as
+    // compact physical filament IDs (for example "123" -> filaments 1,2,3).
+    // Interleaved stripe mode is active for gradient rows only when this list has 3+ IDs.
+    std::string gradient_component_ids;
+    // Optional explicit multi-color weights aligned with gradient_component_ids.
+    // Compact integer list joined by '/': for example "50/25/25".
+    std::string gradient_component_weights;
+
+    // Legacy compatibility flag from earlier prototype serialization.
+    bool pointillism_all_filaments = false;
+
+    // How this mixed row is distributed:
+    // - LayerCycle: one filament per layer based on cadence.
+    // - SameLayerPointillisme: split painted masks in XY on each layer.
+    int distribution_mode = int(Simple);
+
+    // Optional Local-Z cap for this mixed row. 0 disables the cap.
+    int local_z_max_sublayers = 0;
+
+    // Additional XY surface offsets, in mm, applied when this mixed row
+    // resolves to component A or B for an entire layer. Positive values
+    // contract inward; negative values expand outward.
+    float component_a_surface_offset = 0.f;
+    float component_b_surface_offset = 0.f;
+
+    // Whether this mixed filament is enabled (available for assignment).
+    bool enabled = true;
+
+    // True when this mixed filament row was deleted from UI and should stay hidden.
+    bool deleted = false;
+
+    // True when this row was user-created (custom) instead of auto-generated.
+    bool custom = false;
+
+    // True when this row originated from an auto-generated pair. This remains
+    // true even after editing so delete logic can keep the base auto pair
+    // tombstoned instead of letting regeneration resurrect it.
+    bool origin_auto = false;
+
+    // Computed display colour as "#RRGGBB".
+    std::string display_color;
+
+    bool operator==(const MixedFilament &rhs) const
+    {
+        constexpr float k_surface_offset_epsilon = 1e-6f;
+        return component_a == rhs.component_a &&
+               component_b == rhs.component_b &&
+               stable_id   == rhs.stable_id   &&
+               ratio_a     == rhs.ratio_a     &&
+               ratio_b     == rhs.ratio_b     &&
+               mix_b_percent == rhs.mix_b_percent &&
+               manual_pattern == rhs.manual_pattern &&
+               gradient_component_ids == rhs.gradient_component_ids &&
+               gradient_component_weights == rhs.gradient_component_weights &&
+               pointillism_all_filaments == rhs.pointillism_all_filaments &&
+               distribution_mode == rhs.distribution_mode &&
+               local_z_max_sublayers == rhs.local_z_max_sublayers &&
+               std::abs(component_a_surface_offset - rhs.component_a_surface_offset) <= k_surface_offset_epsilon &&
+               std::abs(component_b_surface_offset - rhs.component_b_surface_offset) <= k_surface_offset_epsilon &&
+               enabled      == rhs.enabled &&
+               deleted      == rhs.deleted &&
+               custom       == rhs.custom &&
+               origin_auto  == rhs.origin_auto;
+    }
+    bool operator!=(const MixedFilament &rhs) const { return !(*this == rhs); }
+};
+
+struct MixedFilamentPreviewSettings
+{
+    double nominal_layer_height { 0.2 };
+    double mixed_lower_bound { 0.04 };
+    double mixed_upper_bound { 0.16 };
+    double preferred_a_height { 0.0 };
+    double preferred_b_height { 0.0 };
+    bool   local_z_mode { false };
+    bool   local_z_direct_multicolor { false };
+    size_t wall_loops { 1 };
+};
+
+struct MixedFilamentDisplayContext
+{
+    size_t                       num_physical { 0 };
+    std::vector<std::string>     physical_colors;
+    std::vector<double>          nozzle_diameters;
+    MixedFilamentPreviewSettings preview_settings;
+    bool                         component_bias_enabled { false };
+};
+
+int mixed_filament_effective_local_z_preview_mix_b_percent(const MixedFilament               &mf,
+                                                           const MixedFilamentPreviewSettings &preview_settings);
+bool mixed_filament_supports_bias_apparent_color(const MixedFilament               &mf,
+                                                 const MixedFilamentPreviewSettings &preview_settings,
+                                                 bool                                bias_mode_enabled);
+std::pair<int, int> mixed_filament_apparent_pair_percentages(const MixedFilament               &mf,
+                                                             const MixedFilamentPreviewSettings &preview_settings,
+                                                             const std::vector<double>          &nozzle_diameters,
+                                                             bool                                bias_mode_enabled);
+std::string compute_mixed_filament_display_color(const MixedFilament &entry, const MixedFilamentDisplayContext &context);
+
+// Build a standardized user-facing mixed filament name.
+// - Pattern rows: "Pattern <flattened pattern>" (for example "Pattern 1212354").
+// - Mix rows: "<id>:<pct>% + <id>:<pct>% ..." (for example "1:30% + 2:20% + 3:50%").
+std::string mixed_filament_standardized_name(const MixedFilament &entry, size_t num_physical);
+
+// ---------------------------------------------------------------------------
+// MixedFilamentManager
+//
+// Owns the list of mixed filaments and provides helpers used by the slicing
+// pipeline to resolve virtual IDs back to physical extruders.
+//
+// Virtual filament IDs are numbered starting at (num_physical + 1).  For a
+// 4-extruder printer the first mixed filament has ID 5, the second 6, etc.
+// ---------------------------------------------------------------------------
+class MixedFilamentManager
+{
+public:
+    MixedFilamentManager() = default;
+
+    static void set_auto_generate_enabled(bool enabled);
+    static bool auto_generate_enabled();
+
+    // ---- Auto-generation ------------------------------------------------
+
+    // Rebuild the mixed-filament list from the current set of physical
+    // filament colours.  Generates all C(N,2) pairwise combinations.
+    // Previous ratio/enabled state is preserved when a combination still
+    // exists.
+    void auto_generate(const std::vector<std::string> &filament_colours);
+
+    // Remove a physical filament (1-based ID) from the mixed list.
+    // Any mixed filament that contains the removed component is deleted.
+    // Remaining component IDs are shifted down to stay aligned with physical IDs.
+    void remove_physical_filament(unsigned int deleted_filament_id);
+
+    // Add a custom mixed filament.
+    void add_custom_filament(unsigned int component_a, unsigned int component_b, int mix_b_percent, const std::vector<std::string> &filament_colours);
+
+    // Remove all custom rows, keep auto-generated ones.
+    void clear_custom_entries();
+
+    // Recompute cadence ratios from gradient settings.
+    // gradient_mode: 0 = Layer cycle weighted, 1 = Height weighted.
+    void apply_gradient_settings(int   gradient_mode,
+                                 float lower_bound,
+                                 float upper_bound,
+                                 bool  advanced_dithering = false);
+
+    // Persist mixed rows, including auto/deleted state, into the compact
+    // project-settings string.
+    std::string serialize_custom_entries();
+    void load_custom_entries(const std::string &serialized, const std::vector<std::string> &filament_colours);
+
+    // Normalize a manual mixed-pattern string into compact token form.
+    // Accepts separators and A/B aliases. Returns empty string if invalid.
+    static std::string normalize_manual_pattern(const std::string &pattern);
+    static int         mix_percent_from_manual_pattern(const std::string &pattern);
+
+    // ---- Queries --------------------------------------------------------
+
+    // True when `filament_id` (1-based) refers to a mixed filament.
+    bool is_mixed(unsigned int filament_id, size_t num_physical) const
+    {
+        return mixed_index_from_filament_id(filament_id, num_physical) >= 0;
+    }
+
+    // Resolve a mixed filament ID to a physical extruder (1-based) for the
+    // given layer context. Returns `filament_id` unchanged when it is not a
+    // mixed filament.
+    unsigned int resolve(unsigned int filament_id,
+                         size_t       num_physical,
+                         int          layer_index,
+                         float        layer_print_z = 0.f,
+                         float        layer_height  = 0.f,
+                         bool         force_height_weighted = false) const;
+    unsigned int resolve_perimeter(unsigned int filament_id,
+                                   size_t       num_physical,
+                                   int          layer_index,
+                                   int          perimeter_index,
+                                   float        layer_print_z = 0.f,
+                                   float        layer_height  = 0.f,
+                                   bool         force_height_weighted = false) const;
+    // Resolve the filament ID that should own painted regions on this layer.
+    // Modes that require virtual identity later in G-code generation keep the
+    // original mixed ID; ordinary mixed rows collapse to the current physical
+    // extruder so adjacent same-tool regions can merge.
+    unsigned int effective_painted_region_filament_id(unsigned int filament_id,
+                                                      size_t       num_physical,
+                                                      int          layer_index,
+                                                      float        layer_print_z = 0.f,
+                                                      float        layer_height  = 0.f,
+                                                      float        layer_height_a = 0.f,
+                                                      float        layer_height_b = 0.f,
+                                                      float        base_layer_height = 0.2f) const;
+    float component_surface_offset(unsigned int filament_id,
+                                   size_t       num_physical,
+                                   int          layer_index,
+                                   float        layer_print_z = 0.f,
+                                   float        layer_height  = 0.f,
+                                   bool         force_height_weighted = false) const;
+    std::vector<unsigned int> ordered_perimeter_extruders(unsigned int filament_id,
+                                                          size_t       num_physical,
+                                                          int          layer_index,
+                                                          float        layer_print_z = 0.f,
+                                                          float        layer_height  = 0.f,
+                                                          bool         force_height_weighted = false) const;
+
+    // Map virtual filament ID (1-based, after physical IDs) to index into
+    // m_mixed. Virtual IDs enumerate enabled mixed rows only.
+    int mixed_index_from_filament_id(unsigned int filament_id, size_t num_physical) const;
+
+    // Blend N colours using weighted FilamentMixer blending.
+    // color_percents: vector of (hex_color, percent) where percents sum to 100.
+    static std::string blend_color_multi(
+        const std::vector<std::pair<std::string, int>> &color_percents);
+
+    const MixedFilament *mixed_filament_from_id(unsigned int filament_id, size_t num_physical) const;
+
+    // Compute a display colour by blending two colours with FilamentMixer.
+    static std::string blend_color(const std::string &color_a,
+                                   const std::string &color_b,
+                                   int ratio_a, int ratio_b);
+    static float max_component_surface_offset_mm(float reference_width_mm = 0.4f);
+    static float max_pair_bias_mm(float reference_width_mm = 0.4f);
+    static std::pair<float, float> surface_offset_pair_from_signed_bias(float bias_mm,
+                                                                        float reference_width_mm = 0.4f);
+    static float bias_ui_value_from_surface_offsets(float component_a_surface_offset,
+                                                    float component_b_surface_offset,
+                                                    float reference_width_mm = 0.4f);
+    static int apparent_mix_b_percent(int   mix_b_percent,
+                                      float component_a_surface_offset,
+                                      float component_b_surface_offset,
+                                      float reference_width_mm = 0.4f);
+
+    // ---- Accessors ------------------------------------------------------
+
+    const std::vector<MixedFilament> &mixed_filaments() const { return m_mixed; }
+    std::vector<MixedFilament>       &mixed_filaments()       { return m_mixed; }
+
+    size_t enabled_count() const;
+
+    // Total filament count = num_physical + number of *enabled* mixed filaments.
+    size_t total_filaments(size_t num_physical) const { return num_physical + enabled_count(); }
+
+    // Return the display colours of all enabled mixed filaments (in order).
+    std::vector<std::string> display_colors() const;
+    void set_display_context(const MixedFilamentDisplayContext &context);
+
+private:
+    // Convert a 1-based virtual ID to a 0-based index into m_mixed.
+    size_t index_of(unsigned int filament_id, size_t num_physical) const
+    {
+        return static_cast<size_t>(filament_id - num_physical - 1);
+    }
+
+    void refresh_display_colors(const std::vector<std::string> &filament_colours);
+    uint64_t allocate_stable_id();
+    uint64_t normalize_stable_id(uint64_t stable_id);
+
+    std::vector<MixedFilament> m_mixed;
+    int                        m_gradient_mode       = 0;
+    float                      m_height_lower_bound  = 0.04f;
+    float                      m_height_upper_bound  = 0.16f;
+    bool                       m_advanced_dithering  = false;
+    uint64_t                   m_next_stable_id      = 1;
+    MixedFilamentDisplayContext m_display_context;
+};
+
+} // namespace Slic3r
+
+#endif /* slic3r_MixedFilament_hpp_ */

src/libslic3r/Model.cpp

@@ -2575,15 +2575,26 @@ void ModelVolume::update_extruder_count(size_t extruder_count)
     }
 }
 
-void ModelVolume::update_extruder_count_when_delete_filament(size_t extruder_count, size_t filament_id, int replace_filament_id)
+void ModelVolume::update_extruder_count_when_delete_filament(size_t extruder_count, size_t filament_id, int replace_filament_id,
+                                                             const std::vector<unsigned char>& filament_is_mixed)
 {
     std::vector<int> used_extruders = get_extruders();
     for (int extruder_id : used_extruders) {
-        if (extruder_id >= filament_id) {
+        if (extruder_id >= (int)filament_id) {
             mmu_segmentation_facets.set_enforcer_block_type_limit(*this, (EnforcerBlockerType)(extruder_count), (EnforcerBlockerType)(filament_id), (EnforcerBlockerType)(replace_filament_id));
             break;
         }
     }
+    // Skip erasing the volume's extruder config if it points at a mixed slot —
+    // mixed slots remain valid even after a physical filament deletion.
+    size_t eid = (size_t)extruder_id();
+    if (eid > extruder_count) {
+        bool is_mixed = !filament_is_mixed.empty() && eid >= 1
+                        && (eid - 1) < filament_is_mixed.size()
+                        && filament_is_mixed[eid - 1];
+        if (!is_mixed)
+            this->config.erase("extruder");
+    }
 }
 
 void ModelVolume::center_geometry_after_creation(bool update_source_offset)
@@ -3521,6 +3532,15 @@ bool FacetsAnnotation::set(const TriangleSelector& selector)
     return false;
 }
 
+void FacetsAnnotation::shift_states_above(const ModelVolume &mv, EnforcerBlockerType threshold, int delta)
+{
+    if (empty()) return;
+    TriangleSelector selector(mv.mesh());
+    selector.deserialize(m_data, false);
+    selector.shift_states_above(threshold, delta);
+    this->set(selector);
+}
+
 void FacetsAnnotation::reset()
 {
     m_data.triangles_to_split.clear();

src/libslic3r/Model.hpp

@@ -742,6 +742,9 @@ public:
                                                        EnforcerBlockerType replace_filament = EnforcerBlockerType::NONE);
     indexed_triangle_set get_facets_strict(const ModelVolume& mv, EnforcerBlockerType type) const;
     bool has_facets(const ModelVolume& mv, EnforcerBlockerType type) const;
+    // Shift all non-NONE leaf states >= threshold by delta.
+    // Used to renumber painted filament IDs after a filament slot insertion/deletion.
+    void shift_states_above(const ModelVolume& mv, EnforcerBlockerType threshold, int delta);
     bool empty() const { return m_data.triangles_to_split.empty(); }
 
     // Following method clears the config and increases its timestamp, so the deleted
@@ -925,7 +928,8 @@ public:
     // BBS
     std::vector<int>    get_extruders() const;
     void                update_extruder_count(size_t extruder_count);
-    void                update_extruder_count_when_delete_filament(size_t extruder_count, size_t filament_id, int replace_filament_id = -1);
+    void                update_extruder_count_when_delete_filament(size_t extruder_count, size_t filament_id, int replace_filament_id = -1,
+                                                                   const std::vector<unsigned char>& filament_is_mixed = {});
 
     // Split this volume, append the result to the object owning this volume.
     // Return the number of volumes created from this one.

src/libslic3r/MultiMaterialSegmentation.cpp

@@ -1829,15 +1829,14 @@ static std::vector<std::vector<ExPolygons>> merge_segmented_layers(const std::ve
 {
     const size_t                         num_layers = segmented_regions.size();
     std::vector<std::vector<ExPolygons>> segmented_regions_merged(num_layers);
-    segmented_regions_merged.assign(num_layers, std::vector<ExPolygons>(num_facets_states - 1));
+    segmented_regions_merged.assign(num_layers, std::vector<ExPolygons>(num_facets_states));
     assert(!top_and_bottom_layers.size() || num_facets_states == top_and_bottom_layers.size());
 
     BOOST_LOG_TRIVIAL(debug) << "Print object segmentation - Merging segmented layers in parallel - Begin";
     tbb::parallel_for(tbb::blocked_range<size_t>(0, num_layers), [&segmented_regions, &top_and_bottom_layers, &segmented_regions_merged, &num_facets_states, &throw_on_cancel_callback](const tbb::blocked_range<size_t> &range) {
         for (size_t layer_idx = range.begin(); layer_idx < range.end(); ++layer_idx) {
             assert(segmented_regions[layer_idx].size() == num_facets_states);
-            // Zero is skipped because it is the default color of the volume
-            for (size_t extruder_id = 1; extruder_id < num_facets_states; ++extruder_id) {
+            for (size_t extruder_id = 0; extruder_id < num_facets_states; ++extruder_id) {
                 throw_on_cancel_callback();
                 if (!segmented_regions[layer_idx][extruder_id].empty()) {
                     ExPolygons segmented_regions_trimmed = segmented_regions[layer_idx][extruder_id];
@@ -1849,16 +1848,16 @@ static std::vector<std::vector<ExPolygons>> merge_segmented_layers(const std::ve
                         }
                     }
 
-                    segmented_regions_merged[layer_idx][extruder_id - 1] = std::move(segmented_regions_trimmed);
+                    segmented_regions_merged[layer_idx][extruder_id] = std::move(segmented_regions_trimmed);
                 }
 
                 if (!top_and_bottom_layers.empty() && !top_and_bottom_layers[extruder_id][layer_idx].empty()) {
-                    bool was_top_and_bottom_empty = segmented_regions_merged[layer_idx][extruder_id - 1].empty();
-                    append(segmented_regions_merged[layer_idx][extruder_id - 1], top_and_bottom_layers[extruder_id][layer_idx]);
+                    bool was_top_and_bottom_empty = segmented_regions_merged[layer_idx][extruder_id].empty();
+                    append(segmented_regions_merged[layer_idx][extruder_id], top_and_bottom_layers[extruder_id][layer_idx]);
 
                     // Remove dimples (#7235) appearing after merging side segmentation of the model with tops and bottoms painted layers.
                     if (!was_top_and_bottom_empty)
-                        segmented_regions_merged[layer_idx][extruder_id - 1] = offset2_ex(union_ex(segmented_regions_merged[layer_idx][extruder_id - 1]), float(SCALED_EPSILON), -float(SCALED_EPSILON));
+                        segmented_regions_merged[layer_idx][extruder_id] = offset2_ex(union_ex(segmented_regions_merged[layer_idx][extruder_id]), float(SCALED_EPSILON), -float(SCALED_EPSILON));
                 }
             }
         }
@@ -2195,7 +2194,12 @@ std::vector<std::vector<ExPolygons>> segmentation_by_painting(const PrintObject
 
 // Returns multi-material segmentation based on painting in multi-material segmentation gizmo
 std::vector<std::vector<ExPolygons>> multi_material_segmentation_by_painting(const PrintObject &print_object, const std::function<void()> &throw_on_cancel_callback) {
-    const size_t num_facets_states  = print_object.print()->config().filament_colour.size() + 1;
+    const size_t num_physical_filaments = print_object.print()->config().filament_colour.size();
+    // Virtual (mixed) filament IDs are opaque integers in the range
+    // (num_physical, total_filaments].  The segmentation pipeline treats
+    // all filament IDs as opaque; no assert on id <= num_physical is needed.
+    const size_t num_total_filaments    = print_object.print()->mixed_filament_manager().total_filaments(num_physical_filaments);
+    const size_t num_facets_states      = num_total_filaments + 1;
     const float  max_width          = float(print_object.config().mmu_segmented_region_max_width.value);
     const float  interlocking_depth = float(print_object.config().mmu_segmented_region_interlocking_depth.value);
     const bool   interlocking_beam  = print_object.config().interlocking_beam.value;

src/libslic3r/Preset.cpp

@@ -1264,6 +1264,26 @@ static std::vector<std::string> s_Preset_print_options{
     "zaa_dont_alternate_fill_direction",
     "zaa_min_z",
     "ironing_expansion",
+    // Mixed-filament + dithering + infill-override keys
+    "enable_infill_filament_override",
+    "infill_filament_use_base_first_layers",
+    "infill_filament_use_base_last_layers",
+    "mixed_color_layer_height_a",
+    "mixed_color_layer_height_b",
+    "mixed_filament_gradient_mode",
+    "mixed_filament_height_lower_bound",
+    "mixed_filament_height_upper_bound",
+    "mixed_filament_advanced_dithering",
+    "mixed_filament_component_bias_enabled",
+    "mixed_filament_surface_indentation",
+    "mixed_filament_region_collapse",
+    "mixed_filament_definitions",
+    "dithering_z_step_size",
+    "dithering_local_z_mode",
+    "dithering_local_z_whole_objects",
+    "dithering_local_z_direct_multicolor",
+    "dithering_step_painted_zones_only",
+    "local_z_wipe_tower_purge_lines"
 };
 
 static std::vector<std::string> s_Preset_filament_options {/*"filament_colour", */ "default_filament_colour", "required_nozzle_HRC", "filament_diameter", "pellet_flow_coefficient", "volumetric_speed_coefficients", "filament_type",

src/libslic3r/PresetBundle.cpp

@@ -10,9 +10,11 @@
 #include "libslic3r_version.h"
 
 #include <algorithm>
+#include <map>
 #include <mutex>
 #include <set>
 #include <fstream>
+#include <unordered_map>
 #include <unordered_set>
 #include <boost/filesystem.hpp>
 #include <boost/algorithm/clamp.hpp>
@@ -53,7 +55,9 @@ static std::vector<std::string> s_project_options {
     "flush_multiplier",
     "nozzle_volume_type",
     "filament_map_mode",
-    "filament_map"
+    "filament_map",
+    // FullSpectrum: mixed filament definitions string (virtual slot configuration)
+    "mixed_filament_definitions"
 };
 
 //Orca: add custom as default
@@ -2682,6 +2686,7 @@ void PresetBundle::update_selections(AppConfig &config)
     // exist.
     this->update_compatible(PresetSelectCompatibleType::Always);
     this->update_multi_material_filament_presets();
+    sync_mixed_filaments_from_config();
 
     std::string first_visible_filament_name;
     for (auto & fp : filament_presets) {
@@ -2820,12 +2825,20 @@ void PresetBundle::load_selections(AppConfig &config, const PresetPreferences& p
         project_config.option<ConfigOptionFloats>("flush_multiplier")->values = std::vector<double>(flush_multipliers.begin(), flush_multipliers.end());
     }
 
+    // Restore mixed filament definitions persisted across sessions.
+    if (config.has("presets", "mixed_filament_definitions")) {
+        auto *defs = project_config.option<ConfigOptionString>("mixed_filament_definitions");
+        if (defs)
+            defs->value = config.get("presets", "mixed_filament_definitions");
+    }
+
     // Update visibility of presets based on their compatibility with the active printer.
     // Always try to select a compatible print and filament preset to the current printer preset,
     // as the application may have been closed with an active "external" preset, which does not
     // exist.
     this->update_compatible(PresetSelectCompatibleType::Always);
     this->update_multi_material_filament_presets();
+    sync_mixed_filaments_from_config();
 
     if (initial_printer != nullptr && (preferred_printer == nullptr || initial_printer == preferred_printer)) {
         // Don't run the following code, as we want to activate default filament / SLA material profiles when installing and selecting a new printer.
@@ -2953,6 +2966,11 @@ void PresetBundle::export_selections(AppConfig &config)
                                                               "|");
     config.set_printer_setting(printer_name, "flush_multiplier", flush_multiplier_str);
 
+    // Persist mixed filament definitions across sessions.
+    sync_mixed_filaments_to_config();
+    if (auto *defs = project_config.option<ConfigOptionString>("mixed_filament_definitions"))
+        config.set("presets", "mixed_filament_definitions", defs->value);
+
     // BBS
     //config.set("presets", "sla_print",    sla_prints.get_selected_preset_name());
     //config.set("presets", "sla_material", sla_materials.get_selected_preset_name());
@@ -2997,6 +3015,7 @@ void PresetBundle::set_num_filaments(unsigned int n, std::vector<std::string> ne
     }
 
     update_multi_material_filament_presets();
+    sync_mixed_filaments_from_config();
 }
 void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
 {
@@ -3034,6 +3053,26 @@ void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
     }
 
     update_multi_material_filament_presets();
+    sync_mixed_filaments_from_config();
+}
+
+void PresetBundle::sync_mixed_filaments_from_config()
+{
+    auto *col_opt  = project_config.option<ConfigOptionStrings>("filament_colour");
+    auto *defs_opt = project_config.option<ConfigOptionString>("mixed_filament_definitions");
+    if (!col_opt)
+        return;
+    mixed_filaments.auto_generate(col_opt->values);
+    if (defs_opt && !defs_opt->value.empty())
+        mixed_filaments.load_custom_entries(defs_opt->value, col_opt->values);
+}
+
+void PresetBundle::sync_mixed_filaments_to_config()
+{
+    auto *defs_opt = project_config.option<ConfigOptionString>("mixed_filament_definitions");
+    if (!defs_opt)
+        return;
+    defs_opt->value = mixed_filaments.serialize_custom_entries();
 }
 
 void PresetBundle::update_num_filaments(unsigned int to_del_flament_id)
@@ -3084,6 +3123,11 @@ void PresetBundle::update_num_filaments(unsigned int to_del_flament_id)
     erase_or_resize(filament_color_type->values);
     erase_or_resize(ams_multi_color_filment);
 
+    // Remove any virtual mixed rows that contained this physical filament,
+    // then persist the updated definitions back into project_config.
+    mixed_filaments.remove_physical_filament(to_del_flament_id + 1); // 1-based
+    sync_mixed_filaments_to_config();
+
     update_multi_material_filament_presets(to_del_flament_id);
 }
 
@@ -3143,6 +3187,7 @@ void PresetBundle::get_ams_cobox_infos(AMSComboInfo& combox_info)
 unsigned int PresetBundle::sync_ams_list(std::vector<std::pair<DynamicPrintConfig *,std::string>> &unknowns, bool use_map, std::map<int, AMSMapInfo> &maps, bool enable_append, MergeFilamentInfo &merge_info, bool color_only)
 {
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << "use_map:" << use_map << " enable_append:" << enable_append;
+
     std::vector<std::string> ams_filament_presets;
     std::vector<std::string> ams_filament_colors;
     std::vector<std::string> ams_filament_color_types;
@@ -3287,6 +3332,14 @@ unsigned int PresetBundle::sync_ams_list(std::vector<std::pair<DynamicPrintConfi
     }
     if (ams_filament_presets.empty())
         return 0;
+
+    // AMS sync must not clobber mixed (virtual) filament data — save and restore.
+    // Guard is placed here (after the early-return) so no early-return path bypasses
+    // the restore block below.
+    auto saved_mixed = mixed_filaments;
+    auto *defs_opt_ams = project_config.option<ConfigOptionString>("mixed_filament_definitions");
+    std::string saved_defs = defs_opt_ams ? defs_opt_ams->value : std::string{};
+
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << "get filament_colour and from config";
     ConfigOptionStrings *filament_color = project_config.option<ConfigOptionStrings>("filament_colour");
     ConfigOptionStrings *filament_color_type = project_config.option<ConfigOptionStrings>("filament_colour_type");
@@ -3543,6 +3596,12 @@ unsigned int PresetBundle::sync_ams_list(std::vector<std::pair<DynamicPrintConfi
         if (support_interface_filament_opt->value > filament_color_type->values.size())
             support_interface_filament_opt->value = 0;
     }
+    // Restore mixed (virtual) filament data that AMS sync must not overwrite.
+    mixed_filaments = saved_mixed;
+    if (defs_opt_ams)
+        defs_opt_ams->value = saved_defs;
+    sync_mixed_filaments_from_config();
+
     // Update ams_multi_color_filment
     update_filament_multi_color();
     update_multi_material_filament_presets();
@@ -4095,20 +4154,22 @@ DynamicPrintConfig PresetBundle::full_fff_config(bool apply_extruder, std::optio
     //BBS: add logic for settings check between different system presets
     out.erase("different_settings_to_system");
 
-    static const char* keys[] = {"support_filament", "support_interface_filament", "wipe_tower_filament"};
-    for (size_t i = 0; i < sizeof(keys) / sizeof(keys[0]); ++ i) {
-        std::string key = std::string(keys[i]);
+    const size_t num_total_filaments = this->mixed_filaments.total_filaments(num_filaments);
+
+    static const char* support_keys[] = {"support_filament", "support_interface_filament"};
+    for (size_t i = 0; i < sizeof(support_keys) / sizeof(support_keys[0]); ++ i) {
+        std::string key = std::string(support_keys[i]);
         auto *opt = dynamic_cast<ConfigOptionInt*>(out.option(key, false));
         assert(opt != nullptr);
         opt->value = boost::algorithm::clamp<int>(opt->value, 0, int(num_filaments));
     }
 
-    static const char* keys_with_default[] = {"wall_filament", "sparse_infill_filament", "solid_infill_filament"};
-    for (size_t i = 0; i < sizeof(keys_with_default) / sizeof(keys_with_default[0]); ++ i) {
-        std::string key = std::string(keys_with_default[i]);
+    static const char* feature_keys[] = {"wall_filament", "sparse_infill_filament", "solid_infill_filament", "wipe_tower_filament"};
+    for (size_t i = 0; i < sizeof(feature_keys) / sizeof(feature_keys[0]); ++ i) {
+        std::string key = std::string(feature_keys[i]);
         auto *opt = dynamic_cast<ConfigOptionInt*>(out.option(key, false));
         assert(opt != nullptr);
-        if(opt->value < 0 || opt->value > int(num_filaments))
+        if (opt->value < 0 || opt->value > int(num_total_filaments))
             opt->value = 0;
     }
     out.option<ConfigOptionString >("print_settings_id",    true)->value  = this->prints.get_selected_preset_name();
@@ -4557,6 +4618,10 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
 	this->update_compatible(PresetSelectCompatibleType::Never);
     this->update_multi_material_filament_presets();
 
+    // FullSpectrum: rebuild the MixedFilamentManager from the just-loaded project config.
+    // Per-row warnings for skipped invalid entries are emitted by load_custom_entries.
+    sync_mixed_filaments_from_config();
+
     //BBS
     //const std::string &physical_printer = config.option<ConfigOptionString>("physical_printer_settings_id", true)->value;
     const std::string physical_printer;
@@ -5116,7 +5181,7 @@ void PresetBundle::on_extruders_count_changed(int extruders_count)
     extruder_ams_counts.resize(extruders_count);
 }
 
-void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filament_id)
+void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filament_id, size_t old_num_filaments_arg)
 {
     if (printers.get_edited_preset().printer_technology() != ptFFF)
         return;
@@ -5127,6 +5192,13 @@ void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filam
     // Verify and select the filament presets.
     size_t num_filaments = this->filament_presets.size();
 
+    const bool deleting_filament = (to_delete_filament_id != size_t(-1));
+    const size_t old_num_filaments = (old_num_filaments_arg != size_t(-1))
+        ? old_num_filaments_arg
+        : (deleting_filament ? (num_filaments + 1) : num_filaments);
+    const std::vector<MixedFilament> old_mixed = this->mixed_filaments.mixed_filaments();
+    m_last_filament_id_remap.clear();
+
     auto* nozzle_diameter = static_cast<const ConfigOptionFloats*>(printers.get_edited_preset().config.option("nozzle_diameter"));
     size_t num_extruders  = nozzle_diameter->values.size();
     if (num_extruders > num_filaments) { // Verify validity of the current filament presets.
@@ -5137,7 +5209,8 @@ void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filam
                                                                                       this->filament_presets.back());
         num_filaments = this->filament_presets.size();
     }
-    if (to_delete_filament_id == -1)
+
+    if (!deleting_filament)
         to_delete_filament_id = num_filaments;
 
     // Now verify if flush_volumes_matrix has proper size (it is used to deduce number of extruders in wipe tower generator):
@@ -5188,6 +5261,140 @@ void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filam
             }
         this->project_config.option<ConfigOptionFloats>("flush_volumes_matrix")->values = new_matrix;
     }
+
+    // Build old->new filament ID remap for painted facet data normalization.
+    // This is needed for both deletion and addition of physical filaments so
+    // painted mixed states keep pointing at the same virtual mixed entries.
+    if (old_num_filaments != num_filaments || deleting_filament || old_mixed != this->mixed_filaments.mixed_filaments())
+        build_filament_id_remap(old_mixed, old_num_filaments, num_filaments, deleting_filament,
+                                deleting_filament ? unsigned(to_delete_filament_id + 1) : 0u);
+}
+
+void PresetBundle::update_mixed_filament_id_remap(const std::vector<MixedFilament> &old_mixed,
+                                                  size_t old_num_filaments,
+                                                  size_t new_num_filaments)
+{
+    build_filament_id_remap(old_mixed, old_num_filaments, new_num_filaments, false, 0u);
+}
+
+void PresetBundle::build_filament_id_remap(const std::vector<MixedFilament> &old_mixed,
+                                           size_t old_num_filaments,
+                                           size_t new_num_filaments,
+                                           bool deleting_filament,
+                                           unsigned int deleted_1based)
+{
+    size_t old_enabled_mixed = 0;
+    for (const auto &mf : old_mixed)
+        if (mf.enabled)
+            ++old_enabled_mixed;
+
+    const size_t old_total_filaments = old_num_filaments + old_enabled_mixed;
+    m_last_filament_id_remap.assign(old_total_filaments + 1, 0);
+
+    for (unsigned int old_id = 1; old_id <= unsigned(old_num_filaments); ++old_id) {
+        unsigned int mapped = 0;
+        if (deleting_filament && old_id == deleted_1based) {
+            mapped = 0;
+        } else if (old_id <= unsigned(new_num_filaments)) {
+            mapped = old_id;
+            if (deleting_filament && old_id > deleted_1based)
+                --mapped;
+        }
+        m_last_filament_id_remap[old_id] = mapped;
+    }
+
+    auto canonical_pair = [](unsigned int a, unsigned int b) {
+        return std::make_pair(std::min(a, b), std::max(a, b));
+    };
+
+    std::unordered_map<uint64_t, unsigned int> new_stable_id_to_virtual_id;
+    std::map<std::pair<unsigned int, unsigned int>, std::vector<unsigned int>> new_pair_to_ids;
+    unsigned int next_virtual_id = unsigned(new_num_filaments + 1);
+    for (const auto &mf : this->mixed_filaments.mixed_filaments()) {
+        if (!mf.enabled)
+            continue;
+        if (mf.stable_id != 0)
+            new_stable_id_to_virtual_id.emplace(mf.stable_id, next_virtual_id);
+        new_pair_to_ids[canonical_pair(mf.component_a, mf.component_b)].push_back(next_virtual_id++);
+    }
+
+    std::map<std::pair<unsigned int, unsigned int>, size_t> used_per_pair;
+    size_t stable_id_hits = 0;
+    size_t fallback_pair_hits = 0;
+    size_t missing_hits = 0;
+    unsigned int old_virtual_id = unsigned(old_num_filaments + 1);
+    for (const auto &mf : old_mixed) {
+        if (!mf.enabled)
+            continue;
+
+        unsigned int a = mf.component_a;
+        unsigned int b = mf.component_b;
+        if (a == deleted_1based || b == deleted_1based) {
+            m_last_filament_id_remap[old_virtual_id] = 0;
+            ++missing_hits;
+        } else {
+            bool mapped_by_stable_id = false;
+            if (mf.stable_id != 0) {
+                auto it_stable = new_stable_id_to_virtual_id.find(mf.stable_id);
+                if (it_stable != new_stable_id_to_virtual_id.end()) {
+                    m_last_filament_id_remap[old_virtual_id] = it_stable->second;
+                    mapped_by_stable_id = true;
+                    ++stable_id_hits;
+                }
+            }
+            if (!mapped_by_stable_id) {
+                if (deleting_filament) {
+                    if (a > deleted_1based)
+                        --a;
+                    if (b > deleted_1based)
+                        --b;
+                }
+                const auto key = canonical_pair(a, b);
+                auto it = new_pair_to_ids.find(key);
+                if (it == new_pair_to_ids.end()) {
+                    m_last_filament_id_remap[old_virtual_id] = 0;
+                    ++missing_hits;
+                } else {
+                    size_t &used = used_per_pair[key];
+                    if (used >= it->second.size()) {
+                        m_last_filament_id_remap[old_virtual_id] = 0;
+                        ++missing_hits;
+                    } else {
+                        m_last_filament_id_remap[old_virtual_id] = it->second[used++];
+                        ++fallback_pair_hits;
+                    }
+                }
+            }
+        }
+        ++old_virtual_id;
+    }
+
+    auto summarize_uint_vector = [](const std::vector<unsigned int> &values, size_t max_items = 24) {
+        std::string out = "[";
+        const size_t n = std::min(values.size(), max_items);
+        for (size_t i = 0; i < n; ++i) {
+            if (i > 0)
+                out += ",";
+            out += std::to_string(values[i]);
+        }
+        if (values.size() > n)
+            out += ",...";
+        out += "]";
+        return out;
+    };
+
+    BOOST_LOG_TRIVIAL(warning) << "MF_REMAP preset_bundle"
+                            << " old_physical=" << old_num_filaments
+                            << " new_physical=" << new_num_filaments
+                            << " deleting=" << (deleting_filament ? 1 : 0)
+                            << " deleted_id=" << deleted_1based
+                            << " old_mixed_enabled=" << old_enabled_mixed
+                            << " new_mixed_enabled=" << this->mixed_filaments.enabled_count()
+                            << " stable_id_hits=" << stable_id_hits
+                            << " fallback_pair_hits=" << fallback_pair_hits
+                            << " missing_hits=" << missing_hits
+                            << " remap_size=" << m_last_filament_id_remap.size()
+                            << " remap=" << summarize_uint_vector(m_last_filament_id_remap);
 }
 
 void PresetBundle::update_compatible(PresetSelectCompatibleType select_other_print_if_incompatible, PresetSelectCompatibleType select_other_filament_if_incompatible)

src/libslic3r/PresetBundle.hpp

@@ -4,6 +4,7 @@
 #include "Preset.hpp"
 #include "AppConfig.hpp"
 #include "enum_bitmask.hpp"
+#include "MixedFilament.hpp"
 
 #include <memory>
 #include <shared_mutex>
@@ -289,6 +290,19 @@ public:
     //BBS: check whether this is the only edited filament
     bool is_the_only_edited_filament(unsigned int filament_index);
 
+    // Mixed filament helpers — query virtual slot info
+    bool is_mixed_filament(size_t idx) const {
+        return mixed_filaments.is_mixed(static_cast<unsigned int>(idx + 1),
+                                        filament_presets.size());
+    }
+    size_t total_filament_count() const {
+        return mixed_filaments.total_filaments(filament_presets.size());
+    }
+
+    // Sync the MixedFilamentManager to/from the project_config string key.
+    void sync_mixed_filaments_from_config();
+    void sync_mixed_filaments_to_config();
+
     void reset_default_nozzle_volume_type();
 
     std::vector<int> get_used_tpu_filaments(const std::vector<int> &used_filaments);
@@ -326,6 +340,10 @@ public:
     std::map<int, DynamicPrintConfig> filament_ams_list;
     std::vector<std::vector<std::string>> ams_multi_color_filment;
 
+    // Mixed (virtual) filaments for layer-based colour mixing.
+    // This is the canonical instance; Print::m_mixed_filament_mgr is a slicing-time copy.
+    MixedFilamentManager mixed_filaments;
+
     std::vector<std::map<int, int>> extruder_ams_counts;
 
     // Calibrate
@@ -436,7 +454,23 @@ public:
 
     // Read out the number of extruders from an active printer preset,
     // update size and content of filament_presets.
-    void                        update_multi_material_filament_presets(size_t to_delete_filament_id = size_t(-1));
+    // old_num_filaments: physical filament count before any add/delete (size_t(-1) = auto-detect).
+    void                        update_multi_material_filament_presets(size_t to_delete_filament_id = size_t(-1),
+                                                                       size_t old_num_filaments = size_t(-1));
+    // Rebuild old->new virtual filament mapping after mixed-row enable/delete
+    // changes when the physical filament count itself did not change.
+    void                        update_mixed_filament_id_remap(const std::vector<MixedFilament> &old_mixed,
+                                                               size_t old_num_filaments,
+                                                               size_t new_num_filaments);
+    // Mapping generated during the latest filament count change.
+    // Index is old 1-based filament ID, value is new 1-based filament ID (0 = removed).
+    const std::vector<unsigned int>& last_filament_id_remap() const { return m_last_filament_id_remap; }
+    std::vector<unsigned int> consume_last_filament_id_remap()
+    {
+        std::vector<unsigned int> out = std::move(m_last_filament_id_remap);
+        m_last_filament_id_remap.clear();
+        return out;
+    }
 
     void                        on_extruders_count_changed(int extruder_count);
 
@@ -493,6 +527,12 @@ private:
     void update_filament_multi_color();
     // Update renamed_from and alias maps of system profiles.
     void 						update_system_maps();
+    // Build old->new filament ID remap for painted facet data normalization.
+    void                        build_filament_id_remap(const std::vector<MixedFilament> &old_mixed,
+                                                        size_t old_num_filaments,
+                                                        size_t new_num_filaments,
+                                                        bool deleting_filament,
+                                                        unsigned int deleted_1based);
 
     // Set the is_visible flag for filaments and sla materials,
     // apply defaults based on enabled printers when no filaments/materials are installed.
@@ -513,6 +553,7 @@ private:
     bool validation_mode = false;
     std::string vendor_to_validate = "";
     int m_errors = 0;
+    std::vector<unsigned int> m_last_filament_id_remap;
 
     // Helper function: save preset to bundle directory with common logic
     bool save_preset_to_bundle_dir(Preset& preset, PresetCollection* collection,

src/libslic3r/Print.cpp

@@ -8,6 +8,7 @@
 #include "Flow.hpp"
 #include "Geometry/ConvexHull.hpp"
 #include "I18N.hpp"
+#include "LocalZOrderOptimizer.hpp"
 #include "ShortestPath.hpp"
 #include "Thread.hpp"
 #include "Time.hpp"
@@ -17,6 +18,7 @@
 #include "Utils.hpp"
 #include "PrintConfig.hpp"
 #include "MaterialType.hpp"
+#include "MixedFilament.hpp"
 #include "Model.hpp"
 #include "format.hpp"
 #include <float.h>
@@ -54,6 +56,489 @@ template class PrintState<PrintObjectStep, posCount>;
 PrintRegion::PrintRegion(const PrintRegionConfig &config) : PrintRegion(config, config.hash()) {}
 PrintRegion::PrintRegion(PrintRegionConfig &&config) : PrintRegion(std::move(config), config.hash()) {}
 
+// Estimate how many Local-Z unplanned wipe-tower reserve slots are needed for
+// a given print layer height (used when building the wipe tower plan).
+static size_t estimate_local_z_wipe_tower_reserve_slots(const PrintObject& print_object, coordf_t print_z)
+{
+    const Layer* object_layer = print_object.get_layer_at_printz(print_z, EPSILON);
+    if (object_layer == nullptr)
+        return 0;
+
+    const auto& intervals = print_object.local_z_intervals();
+    const auto& plans     = print_object.local_z_sublayer_plan();
+    if (intervals.empty() || plans.empty())
+        return 0;
+
+    const size_t layer_id = size_t(object_layer->id());
+    const auto interval_it = std::find_if(intervals.begin(), intervals.end(), [layer_id](const LocalZInterval& interval) {
+        return interval.layer_id == layer_id;
+    });
+    if (interval_it == intervals.end() || !interval_it->has_mixed_paint || interval_it->sublayer_count <= 1 ||
+        interval_it->first_sublayer_idx >= plans.size()) {
+        return 0;
+    }
+
+    const size_t first_idx = interval_it->first_sublayer_idx;
+    const size_t end_idx   = std::min(plans.size(), first_idx + interval_it->sublayer_count);
+    size_t reserve_slots = 0;
+    int    previous_extruder = -1;
+    for (size_t plan_idx = first_idx; plan_idx < end_idx; ++plan_idx) {
+        const SubLayerPlan& plan = plans[plan_idx];
+        if (!plan.split_interval)
+            continue;
+
+        for (size_t extruder_id = 0; extruder_id < plan.painted_masks_by_extruder.size(); ++extruder_id) {
+            if (plan.painted_masks_by_extruder[extruder_id].empty())
+                continue;
+            if (previous_extruder != int(extruder_id)) {
+                ++reserve_slots;
+                previous_extruder = int(extruder_id);
+            }
+        }
+    }
+
+    if (reserve_slots > 0)
+        ++reserve_slots;
+    return reserve_slots;
+}
+
+namespace {
+
+constexpr double LOCAL_Z_PERIMETER_MASK_EXPAND_MM = 0.10;
+
+struct LocalZWipeTowerToolchange
+{
+    unsigned int old_tool { 0 };
+    unsigned int new_tool { 0 };
+};
+
+struct LocalZWipeTowerPassRef
+{
+    size_t                    layer_to_print_idx { 0 };
+    const SubLayerPlan       *plan { nullptr };
+    std::vector<unsigned int> extruders;
+};
+
+static inline ExPolygons local_z_compensate_masks_for_wipe_tower(const ExPolygons &src_masks,
+                                                                 const float       delta_scaled,
+                                                                 const bool        fallback_to_source)
+{
+    if (src_masks.empty() || std::abs(delta_scaled) <= EPSILON)
+        return src_masks;
+
+    ExPolygons compensated = offset_ex(src_masks, delta_scaled);
+    if (!compensated.empty() && compensated.size() > 1)
+        compensated = union_ex(compensated);
+
+    if (compensated.empty() && fallback_to_source)
+        return src_masks;
+    return compensated;
+}
+
+static bool local_z_segments_exist(Polylines segments)
+{
+    for (Polyline &segment : segments) {
+        if (segment.is_valid())
+            return true;
+    }
+    return false;
+}
+
+static bool extrusion_collection_has_local_z_perimeter_segment(const ExtrusionEntityCollection &source,
+                                                               const ExPolygons               &include_masks)
+{
+    if (source.entities.empty() || include_masks.empty())
+        return false;
+
+    ExtrusionEntityCollection flattened = source.flatten(false);
+    for (const ExtrusionEntity *entity : flattened.entities) {
+        if (const auto *path = dynamic_cast<const ExtrusionPath*>(entity)) {
+            if (local_z_segments_exist(intersection_pl(Polylines{path->polyline.to_polyline()}, include_masks)))
+                return true;
+        } else if (const auto *multipath = dynamic_cast<const ExtrusionMultiPath*>(entity)) {
+            for (const ExtrusionPath &path : multipath->paths) {
+                if (local_z_segments_exist(intersection_pl(Polylines{path.polyline.to_polyline()}, include_masks)))
+                    return true;
+            }
+        } else if (const auto *loop = dynamic_cast<const ExtrusionLoop*>(entity)) {
+            for (const ExtrusionPath &path : loop->paths) {
+                if (local_z_segments_exist(intersection_pl(Polylines{path.polyline.to_polyline()}, include_masks)))
+                    return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+static bool layer_has_local_z_perimeters(const Layer &layer, const ExPolygons &pass_masks)
+{
+    if (pass_masks.empty())
+        return false;
+
+    for (const LayerRegion *layer_region : layer.regions()) {
+        for (const ExtrusionEntity *entity : layer_region->perimeters.entities) {
+            const auto *extrusions = dynamic_cast<const ExtrusionEntityCollection*>(entity);
+            if (extrusions == nullptr)
+                continue;
+            if (extrusion_collection_has_local_z_perimeter_segment(*extrusions, pass_masks))
+                return true;
+        }
+    }
+
+    return false;
+}
+
+static inline int shared_local_z_extruder_for_wipe_tower(const std::vector<unsigned int> &lhs,
+                                                         const std::vector<unsigned int> &rhs)
+{
+    for (unsigned int extruder_id : lhs) {
+        if (std::find(rhs.begin(), rhs.end(), extruder_id) != rhs.end())
+            return static_cast<int>(extruder_id);
+    }
+    return -1;
+}
+
+static std::vector<unsigned int> rotate_extruders_to_start_with(const std::vector<unsigned int> &extruders,
+                                                                unsigned int                      start_extruder)
+{
+    std::vector<unsigned int> rotated = extruders;
+    auto it = std::find(rotated.begin(), rotated.end(), start_extruder);
+    if (it != rotated.end())
+        std::rotate(rotated.begin(), it, rotated.end());
+    return rotated;
+}
+
+static std::vector<LocalZWipeTowerToolchange> collect_local_z_wipe_tower_toolchanges(
+    const Print                              &print,
+    const std::vector<GCode::LayerToPrint>   &layers,
+    int                                       start_extruder)
+{
+    std::vector<LocalZWipeTowerPassRef> pass_refs;
+    const bool  local_z_whole_objects_enabled = print.full_print_config().opt_bool("dithering_local_z_whole_objects");
+    const float local_z_perimeter_mask_expand = float(scale_(LOCAL_Z_PERIMETER_MASK_EXPAND_MM));
+
+    for (size_t layer_to_print_idx = 0; layer_to_print_idx < layers.size(); ++layer_to_print_idx) {
+        const GCode::LayerToPrint &layer_to_print = layers[layer_to_print_idx];
+        if (layer_to_print.object_layer == nullptr)
+            continue;
+
+        const PrintObject *print_object =
+            layer_to_print.original_object != nullptr ? layer_to_print.original_object : layer_to_print.object();
+        if (print_object == nullptr)
+            continue;
+
+        const size_t       layer_id   = size_t(layer_to_print.object_layer->id());
+        const auto        &intervals  = print_object->local_z_intervals();
+        const auto        &plans      = print_object->local_z_sublayer_plan();
+        const auto interval_it = std::find_if(intervals.begin(), intervals.end(), [layer_id](const LocalZInterval &interval) {
+            return interval.layer_id == layer_id;
+        });
+        if (interval_it == intervals.end() || !interval_it->has_mixed_paint || interval_it->sublayer_count <= 1 ||
+            interval_it->first_sublayer_idx >= plans.size()) {
+            continue;
+        }
+
+        const size_t first_idx = interval_it->first_sublayer_idx;
+        const size_t end_idx   = std::min(plans.size(), first_idx + interval_it->sublayer_count);
+        for (size_t plan_idx = first_idx; plan_idx < end_idx; ++plan_idx) {
+            const SubLayerPlan &plan = plans[plan_idx];
+            if (!plan.split_interval)
+                continue;
+
+            const size_t plan_mask_slots =
+                std::max(plan.painted_masks_by_extruder.size(), plan.fixed_painted_masks_by_extruder.size());
+            std::vector<ExPolygons> compensated_masks_by_extruder(plan_mask_slots, ExPolygons());
+
+            ExPolygons fixed_raw_masks_union;
+            for (const ExPolygons &fixed_masks : plan.fixed_painted_masks_by_extruder) {
+                if (!fixed_masks.empty())
+                    append(fixed_raw_masks_union, fixed_masks);
+            }
+            if (!fixed_raw_masks_union.empty() && fixed_raw_masks_union.size() > 1)
+                fixed_raw_masks_union = union_ex(fixed_raw_masks_union);
+
+            const ExPolygons fixed_compensated_guard =
+                fixed_raw_masks_union.empty() ?
+                    ExPolygons() :
+                    local_z_compensate_masks_for_wipe_tower(fixed_raw_masks_union, local_z_perimeter_mask_expand, true);
+
+            for (size_t extruder_id = 0; extruder_id < plan_mask_slots; ++extruder_id) {
+                const ExPolygons mixed_raw_masks =
+                    extruder_id < plan.painted_masks_by_extruder.size() ? plan.painted_masks_by_extruder[extruder_id] : ExPolygons();
+                const ExPolygons fixed_raw_masks =
+                    extruder_id < plan.fixed_painted_masks_by_extruder.size() ? plan.fixed_painted_masks_by_extruder[extruder_id] :
+                                                                               ExPolygons();
+                if (mixed_raw_masks.empty() && fixed_raw_masks.empty())
+                    continue;
+
+                ExPolygons compensated;
+                if (!mixed_raw_masks.empty()) {
+                    ExPolygons compensated_mixed =
+                        local_z_compensate_masks_for_wipe_tower(mixed_raw_masks, local_z_perimeter_mask_expand, true);
+                    if (local_z_whole_objects_enabled && !fixed_compensated_guard.empty())
+                        compensated_mixed = diff_ex(compensated_mixed, fixed_compensated_guard);
+                    if (!compensated_mixed.empty())
+                        append(compensated, compensated_mixed);
+                }
+                if (!fixed_raw_masks.empty())
+                    append(compensated, fixed_raw_masks);
+                if (!compensated.empty() && compensated.size() > 1)
+                    compensated = union_ex(compensated);
+                compensated_masks_by_extruder[extruder_id] = std::move(compensated);
+            }
+
+            LocalZWipeTowerPassRef pass_ref;
+            pass_ref.layer_to_print_idx = layer_to_print_idx;
+            pass_ref.plan               = &plan;
+            for (size_t extruder_id = 0; extruder_id < plan.painted_masks_by_extruder.size(); ++extruder_id) {
+                if (extruder_id >= compensated_masks_by_extruder.size())
+                    continue;
+                const ExPolygons &pass_masks = compensated_masks_by_extruder[extruder_id];
+                if (pass_masks.empty())
+                    continue;
+                if (layer_has_local_z_perimeters(*layer_to_print.object_layer, pass_masks))
+                    pass_ref.extruders.push_back(unsigned(extruder_id));
+            }
+
+            if (!pass_ref.extruders.empty())
+                pass_refs.emplace_back(std::move(pass_ref));
+        }
+    }
+
+    std::sort(pass_refs.begin(), pass_refs.end(), [](const LocalZWipeTowerPassRef &lhs, const LocalZWipeTowerPassRef &rhs) {
+        assert(lhs.plan != nullptr && rhs.plan != nullptr);
+        if (lhs.plan->print_z != rhs.plan->print_z)
+            return lhs.plan->print_z < rhs.plan->print_z;
+        if (lhs.layer_to_print_idx != rhs.layer_to_print_idx)
+            return lhs.layer_to_print_idx < rhs.layer_to_print_idx;
+        return lhs.plan->pass_index < rhs.plan->pass_index;
+    });
+
+    auto collect_toolchanges_legacy = [&](int start_tool) {
+        std::vector<LocalZWipeTowerToolchange> legacy_toolchanges;
+        int active_extruder = start_tool;
+        size_t pass_ref_idx = 0;
+        while (pass_ref_idx < pass_refs.size()) {
+            size_t pass_group_end = pass_ref_idx + 1;
+            while (pass_group_end < pass_refs.size() &&
+                   std::abs(pass_refs[pass_ref_idx].plan->print_z - pass_refs[pass_group_end].plan->print_z) <= EPSILON) {
+                ++pass_group_end;
+            }
+
+            std::vector<unsigned int> pass_group_extruders;
+            for (size_t group_idx = pass_ref_idx; group_idx < pass_group_end; ++group_idx)
+                for (unsigned int extruder_id : pass_refs[group_idx].extruders)
+                    if (std::find(pass_group_extruders.begin(), pass_group_extruders.end(), extruder_id) == pass_group_extruders.end())
+                        pass_group_extruders.push_back(extruder_id);
+
+            std::vector<unsigned int> next_group_extruders;
+            if (pass_group_end < pass_refs.size()) {
+                size_t next_group_end = pass_group_end + 1;
+                while (next_group_end < pass_refs.size() &&
+                       std::abs(pass_refs[pass_group_end].plan->print_z - pass_refs[next_group_end].plan->print_z) <= EPSILON) {
+                    ++next_group_end;
+                }
+                for (size_t group_idx = pass_group_end; group_idx < next_group_end; ++group_idx)
+                    for (unsigned int extruder_id : pass_refs[group_idx].extruders)
+                        if (std::find(next_group_extruders.begin(), next_group_extruders.end(), extruder_id) == next_group_extruders.end())
+                            next_group_extruders.push_back(extruder_id);
+            }
+
+            const int preferred_last_extruder =
+                shared_local_z_extruder_for_wipe_tower(pass_group_extruders, next_group_extruders);
+            const std::vector<unsigned int> ordered_group_extruders =
+                LocalZOrderOptimizer::order_bucket_extruders(pass_group_extruders, active_extruder, preferred_last_extruder);
+
+            for (unsigned int extruder_id : ordered_group_extruders) {
+                if (active_extruder >= 0 && active_extruder != int(extruder_id))
+                    legacy_toolchanges.push_back(LocalZWipeTowerToolchange{unsigned(active_extruder), extruder_id});
+                active_extruder = int(extruder_id);
+            }
+
+            pass_ref_idx = pass_group_end;
+        }
+
+        return legacy_toolchanges;
+    };
+
+    const bool dependency_chain_mode =
+        !pass_refs.empty() &&
+        std::all_of(pass_refs.begin(), pass_refs.end(), [](const LocalZWipeTowerPassRef &pass_ref) {
+            return pass_ref.plan != nullptr && pass_ref.plan->dependency_group != 0;
+        });
+    if (!dependency_chain_mode)
+        return collect_toolchanges_legacy(start_extruder);
+
+    struct ChainKey {
+        size_t layer_to_print_idx { 0 };
+        size_t dependency_group { 0 };
+
+        bool operator<(const ChainKey &rhs) const
+        {
+            if (layer_to_print_idx != rhs.layer_to_print_idx)
+                return layer_to_print_idx < rhs.layer_to_print_idx;
+            return dependency_group < rhs.dependency_group;
+        }
+    };
+    struct PassState {
+        const LocalZWipeTowerPassRef *pass_ref { nullptr };
+        std::vector<unsigned int>     remaining_extruders;
+        size_t                        chain_idx { 0 };
+        size_t                        chain_pos { 0 };
+        bool                          ready { false };
+        bool                          completed { false };
+    };
+
+    std::map<ChainKey, size_t> chain_index_by_key;
+    std::vector<std::vector<size_t>> chains;
+    std::vector<PassState>           pass_states;
+    pass_states.reserve(pass_refs.size());
+    for (const LocalZWipeTowerPassRef &pass_ref : pass_refs) {
+        ChainKey chain_key { pass_ref.layer_to_print_idx, pass_ref.plan->dependency_group };
+        auto [it_chain, inserted] = chain_index_by_key.emplace(chain_key, chains.size());
+        if (inserted)
+            chains.emplace_back();
+
+        const size_t chain_idx = it_chain->second;
+        const size_t pass_state_idx = pass_states.size();
+        pass_states.push_back(PassState{ &pass_ref, pass_ref.extruders, chain_idx, 0, false, false });
+        chains[chain_idx].push_back(pass_state_idx);
+    }
+
+    for (std::vector<size_t> &chain : chains) {
+        std::sort(chain.begin(), chain.end(), [&pass_states](size_t lhs_idx, size_t rhs_idx) {
+            const SubLayerPlan &lhs = *pass_states[lhs_idx].pass_ref->plan;
+            const SubLayerPlan &rhs = *pass_states[rhs_idx].pass_ref->plan;
+            if (lhs.dependency_order != rhs.dependency_order)
+                return lhs.dependency_order < rhs.dependency_order;
+            if (std::abs(lhs.print_z - rhs.print_z) > EPSILON)
+                return lhs.print_z < rhs.print_z;
+            return lhs.pass_index < rhs.pass_index;
+        });
+        for (size_t chain_pos = 0; chain_pos < chain.size(); ++chain_pos)
+            pass_states[chain[chain_pos]].chain_pos = chain_pos;
+        if (!chain.empty())
+            pass_states[chain.front()].ready = true;
+    }
+
+    auto pass_contains_extruder = [](const PassState &pass_state, unsigned int extruder_id) {
+        return std::find(pass_state.remaining_extruders.begin(), pass_state.remaining_extruders.end(), extruder_id) !=
+               pass_state.remaining_extruders.end();
+    };
+
+    auto choose_ready_extruder = [&](int active_extruder) -> int {
+        std::vector<unsigned int> ready_extruders;
+        for (const PassState &pass_state : pass_states) {
+            if (!pass_state.ready || pass_state.completed)
+                continue;
+            for (unsigned int extruder_id : pass_state.remaining_extruders)
+                if (std::find(ready_extruders.begin(), ready_extruders.end(), extruder_id) == ready_extruders.end())
+                    ready_extruders.push_back(extruder_id);
+        }
+        if (ready_extruders.empty())
+            return -1;
+        if (active_extruder >= 0 &&
+            std::find(ready_extruders.begin(), ready_extruders.end(), unsigned(active_extruder)) != ready_extruders.end()) {
+            return active_extruder;
+        }
+
+        int    best_extruder = -1;
+        size_t best_ready_count = 0;
+        size_t best_future_count = 0;
+        for (unsigned int extruder_id : ready_extruders) {
+            size_t ready_count = 0;
+            size_t future_count = 0;
+            for (const PassState &pass_state : pass_states) {
+                if (pass_state.completed || !pass_contains_extruder(pass_state, extruder_id))
+                    continue;
+                ++future_count;
+                if (pass_state.ready)
+                    ++ready_count;
+            }
+
+            if (best_extruder < 0 ||
+                ready_count > best_ready_count ||
+                (ready_count == best_ready_count && future_count > best_future_count) ||
+                (ready_count == best_ready_count && future_count == best_future_count && extruder_id < unsigned(best_extruder))) {
+                best_extruder = int(extruder_id);
+                best_ready_count = ready_count;
+                best_future_count = future_count;
+            }
+        }
+        return best_extruder;
+    };
+
+    std::vector<LocalZWipeTowerToolchange> toolchanges;
+    int                                    active_extruder = start_extruder;
+    size_t                                 completed_passes = 0;
+    while (completed_passes < pass_states.size()) {
+        const int chosen_extruder = choose_ready_extruder(active_extruder);
+        if (chosen_extruder < 0) {
+            BOOST_LOG_TRIVIAL(warning) << "Local-Z wipe tower dependency scheduler deadlocked, falling back"
+                                       << " start_extruder=" << start_extruder
+                                       << " pass_count=" << pass_refs.size();
+            return collect_toolchanges_legacy(start_extruder);
+        }
+
+        if (active_extruder >= 0 && active_extruder != chosen_extruder)
+            toolchanges.push_back(LocalZWipeTowerToolchange{unsigned(active_extruder), unsigned(chosen_extruder)});
+        active_extruder = chosen_extruder;
+
+        bool                completed_any = false;
+        std::vector<size_t> newly_completed;
+        for (size_t pass_state_idx = 0; pass_state_idx < pass_states.size(); ++pass_state_idx) {
+            PassState &pass_state = pass_states[pass_state_idx];
+            if (!pass_state.ready || pass_state.completed)
+                continue;
+
+            auto it_extruder = std::find(pass_state.remaining_extruders.begin(),
+                                         pass_state.remaining_extruders.end(),
+                                         unsigned(chosen_extruder));
+            if (it_extruder == pass_state.remaining_extruders.end())
+                continue;
+
+            pass_state.remaining_extruders.erase(it_extruder);
+            completed_any = true;
+            if (pass_state.remaining_extruders.empty())
+                newly_completed.push_back(pass_state_idx);
+        }
+
+        if (!completed_any) {
+            BOOST_LOG_TRIVIAL(warning) << "Local-Z wipe tower dependency scheduler made no progress, falling back"
+                                       << " start_extruder=" << start_extruder
+                                       << " active_extruder=" << active_extruder
+                                       << " chosen_extruder=" << chosen_extruder
+                                       << " pass_count=" << pass_refs.size();
+            return collect_toolchanges_legacy(start_extruder);
+        }
+
+        for (size_t pass_state_idx : newly_completed) {
+            PassState &pass_state = pass_states[pass_state_idx];
+            if (pass_state.completed)
+                continue;
+
+            pass_state.ready = false;
+            pass_state.completed = true;
+            ++completed_passes;
+
+            const std::vector<size_t> &chain = chains[pass_state.chain_idx];
+            const size_t next_chain_pos = pass_state.chain_pos + 1;
+            if (next_chain_pos < chain.size())
+                pass_states[chain[next_chain_pos]].ready = true;
+        }
+    }
+
+    BOOST_LOG_TRIVIAL(info) << "Local-Z wipe tower dependency scheduler"
+                            << " start_extruder=" << start_extruder
+                            << " pass_count=" << pass_refs.size()
+                            << " chain_count=" << chains.size()
+                            << " toolchanges=" << toolchanges.size();
+    return toolchanges;
+}
+
+} // namespace
+
 //BBS
 // ORCA: Now this is a parameter
 //float Print::min_skirt_length = 0;
@@ -275,6 +760,23 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
             || opt_key == "filament_shrinkage_compensation_z"
             || opt_key == "resolution"
             || opt_key == "precise_z_height"
+            // Mixed-filament and dithering keys require full reslicing so virtual
+            // filament assignments are re-evaluated and layer z-plans recomputed.
+            || opt_key == "dithering_z_step_size"
+            || opt_key == "dithering_local_z_mode"
+            || opt_key == "dithering_local_z_whole_objects"
+            || opt_key == "dithering_local_z_direct_multicolor"
+            || opt_key == "dithering_step_painted_zones_only"
+            || opt_key == "mixed_filament_gradient_mode"
+            || opt_key == "mixed_color_layer_height_a"
+            || opt_key == "mixed_color_layer_height_b"
+            || opt_key == "mixed_filament_height_lower_bound"
+            || opt_key == "mixed_filament_height_upper_bound"
+            || opt_key == "mixed_filament_advanced_dithering"
+            || opt_key == "mixed_filament_component_bias_enabled"
+            || opt_key == "mixed_filament_surface_indentation"
+            || opt_key == "mixed_filament_region_collapse"
+            || opt_key == "mixed_filament_definitions"
             // Spiral Vase forces different kind of slicing than the normal model:
             // In Spiral Vase mode, holes are closed and only the largest area contour is kept at each layer.
             // Therefore toggling the Spiral Vase on / off requires complete reslicing.
@@ -1358,7 +1860,7 @@ StringObjectException Print::validate(StringObjectException *warning, Polygons*
             layer_height_profiles.assign(m_objects.size(), std::vector<coordf_t>());
         std::vector<coordf_t>   &profile      = layer_height_profiles[print_object_idx];
         if (profile.empty())
-            PrintObject::update_layer_height_profile(*print_object.model_object(), print_object.slicing_parameters(), profile);
+            PrintObject::update_layer_height_profile(*print_object.model_object(), print_object.slicing_parameters(), profile, &print_object);
         return profile;
     };
 
@@ -2452,11 +2954,26 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
             std::vector<std::vector<unsigned int>> all_filaments;
             for (print_object_instance_sequential_active = print_object_instances_ordering.begin(); print_object_instance_sequential_active != print_object_instances_ordering.end(); ++print_object_instance_sequential_active) {
                 tool_ordering = ToolOrdering(*(*print_object_instance_sequential_active)->print_object, initial_extruder_id);
+                const auto& mgr = this->mixed_filament_manager();
+                size_t num_phys = this->config().filament_colour.values.size();
                 for (size_t idx = 0; idx < tool_ordering.layer_tools().size(); ++idx) {
-                    auto& layer_filament = tool_ordering.layer_tools()[idx].extruders;
-                    all_filaments.emplace_back(layer_filament);
+                    auto layer_filament = tool_ordering.layer_tools()[idx].extruders;
+                    std::vector<unsigned int> expanded;
+                    for (unsigned int u : layer_filament) {
+                        if (mgr.is_mixed(u, num_phys)) {
+                            if (auto* mf = mgr.mixed_filament_from_id(u, num_phys)) {
+                                expanded.push_back(mf->component_a);
+                                expanded.push_back(mf->component_b);
+                            }
+                        } else {
+                            expanded.push_back(u);
+                        }
+                    }
+                    std::sort(expanded.begin(), expanded.end());
+                    expanded.erase(std::unique(expanded.begin(), expanded.end()), expanded.end());
                     if (idx == 0)
-                        first_layer_used_filaments.insert(first_layer_used_filaments.end(), layer_filament.begin(), layer_filament.end());
+                        first_layer_used_filaments.insert(first_layer_used_filaments.end(), expanded.begin(), expanded.end());
+                    all_filaments.emplace_back(std::move(expanded));
                 }
             }
             sort_remove_duplicates(first_layer_used_filaments);
@@ -3419,6 +3936,8 @@ void Print::_make_wipe_tower()
         // Initialize the wipe tower.
         WipeTower2 wipe_tower(m_config, m_default_region_config, m_plate_index, m_origin, wipe_volumes,
                               m_wipe_tower_data.tool_ordering.first_extruder());
+        const std::vector<std::pair<coordf_t, std::vector<GCode::LayerToPrint>>> layers_to_print = GCode::collect_layers_to_print(*this);
+        size_t layers_to_print_idx = 0;
 
         // wipe_tower.set_retract();
         // wipe_tower.set_zhop();
@@ -3437,10 +3956,52 @@ void Print::_make_wipe_tower()
             for (auto &layer_tools : m_wipe_tower_data.tool_ordering.layer_tools()) { // for all layers
                 if (!layer_tools.has_wipe_tower)
                     continue;
+                while (layers_to_print_idx + 1 < layers_to_print.size() &&
+                       layers_to_print[layers_to_print_idx].first + EPSILON < layer_tools.print_z) {
+                    ++layers_to_print_idx;
+                }
+
+                const std::vector<GCode::LayerToPrint> *layers_with_same_print_z = nullptr;
+                if (layers_to_print_idx < layers_to_print.size() &&
+                    std::abs(layers_to_print[layers_to_print_idx].first - layer_tools.print_z) <= EPSILON) {
+                    layers_with_same_print_z = &layers_to_print[layers_to_print_idx].second;
+                }
+
                 bool first_layer = &layer_tools == &m_wipe_tower_data.tool_ordering.front();
+
+                if (m_config.dithering_local_z_mode && layers_with_same_print_z != nullptr) {
+                    const std::vector<LocalZWipeTowerToolchange> local_z_toolchanges =
+                        collect_local_z_wipe_tower_toolchanges(*this, *layers_with_same_print_z, int(current_extruder_id));
+                    if (!local_z_toolchanges.empty()) {
+                        std::ostringstream local_z_sequence;
+                        for (size_t toolchange_idx = 0; toolchange_idx < local_z_toolchanges.size(); ++toolchange_idx) {
+                            if (toolchange_idx != 0)
+                                local_z_sequence << ",";
+                            local_z_sequence << local_z_toolchanges[toolchange_idx].old_tool << "->"
+                                             << local_z_toolchanges[toolchange_idx].new_tool;
+                        }
+
+                        BOOST_LOG_TRIVIAL(debug) << "Local-Z wipe tower preplan"
+                                                 << " print_z=" << layer_tools.print_z
+                                                 << " start_tool=" << current_extruder_id
+                                                 << " nominal_toolchanges=" << layer_tools.extruders.size()
+                                                 << " local_z_toolchanges=" << local_z_toolchanges.size()
+                                                 << " sequence=" << local_z_sequence.str();
+                    }
+                    for (const LocalZWipeTowerToolchange &toolchange : local_z_toolchanges) {
+                        wipe_tower.plan_local_z_toolchange((float) layer_tools.print_z, (float) layer_tools.wipe_tower_layer_height,
+                                                           toolchange.old_tool, toolchange.new_tool, (float) m_config.prime_volume);
+                    }
+                    if (!local_z_toolchanges.empty())
+                        current_extruder_id = local_z_toolchanges.back().new_tool;
+                }
+
+                const std::vector<unsigned int> nominal_layer_extruders =
+                    rotate_extruders_to_start_with(layer_tools.extruders, current_extruder_id);
+
                 wipe_tower.plan_toolchange((float) layer_tools.print_z, (float) layer_tools.wipe_tower_layer_height, current_extruder_id,
                                            current_extruder_id, false);
-                for (const auto extruder_id : layer_tools.extruders) {
+                for (const auto extruder_id : nominal_layer_extruders) {
                     if ((first_layer && extruder_id == m_wipe_tower_data.tool_ordering.all_extruders().back()) || extruder_id !=
                         current_extruder_id) {
                         float volume_to_wipe = m_config.prime_volume;
@@ -3465,6 +4026,18 @@ void Print::_make_wipe_tower()
                     }
                 }
                 layer_tools.wiping_extrusions().ensure_perimeters_infills_order(*this);
+
+                // Reserve Local-Z wipe-tower slots for unplanned toolchanges during Local-Z sub-layer emission.
+                if (m_config.dithering_local_z_mode) {
+                    size_t local_z_reserve_slots = 0;
+                    for (const PrintObject* print_object : m_objects)
+                        local_z_reserve_slots += estimate_local_z_wipe_tower_reserve_slots(*print_object, layer_tools.print_z);
+                    if (local_z_reserve_slots > 0) {
+                        wipe_tower.plan_local_z_reserve((float) layer_tools.print_z, (float) layer_tools.wipe_tower_layer_height,
+                                                        local_z_reserve_slots, (float) m_config.prime_volume);
+                    }
+                }
+
                 if (&layer_tools == &m_wipe_tower_data.tool_ordering.back() || (&layer_tools + 1)->wipe_tower_partitions == 0)
                     break;
             }
@@ -3472,13 +4045,18 @@ void Print::_make_wipe_tower()
 
         // Generate the wipe tower layers.
         m_wipe_tower_data.tool_changes.reserve(m_wipe_tower_data.tool_ordering.layer_tools().size());
-        wipe_tower.generate(m_wipe_tower_data.tool_changes);
+        m_wipe_tower_data.local_z_tool_changes.reserve(m_wipe_tower_data.tool_ordering.layer_tools().size());
+        wipe_tower.generate(m_wipe_tower_data.tool_changes, m_wipe_tower_data.local_z_tool_changes);
+        BOOST_LOG_TRIVIAL(debug) << "Wipe tower generation completed"
+                                 << " nominal_layers=" << m_wipe_tower_data.tool_changes.size()
+                                 << " local_z_layers=" << m_wipe_tower_data.local_z_tool_changes.size();
         m_wipe_tower_data.depth             = wipe_tower.get_depth();
         m_wipe_tower_data.z_and_depth_pairs = wipe_tower.get_z_and_depth_pairs();
         m_wipe_tower_data.brim_width        = wipe_tower.get_brim_width();
         m_wipe_tower_data.height            = wipe_tower.get_wipe_tower_height();
         m_wipe_tower_data.bbx               = wipe_tower.get_bbx();
         m_wipe_tower_data.rib_offset        = wipe_tower.get_rib_offset();
+        m_wipe_tower_data.local_z_reserve_boxes = wipe_tower.get_local_z_reserve_boxes();
 
         // Unload the current filament over the purge tower.
         coordf_t layer_height = m_objects.front()->config().layer_height.value;

src/libslic3r/Print.hpp

@@ -4,6 +4,7 @@
 #include "PrintBase.hpp"
 #include "Fill/FillAdaptive.hpp"
 #include "Fill/FillLightning.hpp"
+#include "MixedFilament.hpp"
 
 #include "BoundingBox.hpp"
 #include "ExtrusionEntityCollection.hpp"
@@ -54,6 +55,35 @@ struct groupedVolumeSlices
     ExPolygons              slices;
 };
 
+// Phase A local-Z dithering planner cache.
+struct LocalZInterval
+{
+    size_t layer_id { 0 };
+    double z_lo { 0.0 };
+    double z_hi { 0.0 };
+    double base_height { 0.0 };
+    double sublayer_height { 0.0 };
+    bool   has_mixed_paint { false };
+    size_t first_sublayer_idx { 0 };
+    size_t sublayer_count { 0 };
+};
+
+struct SubLayerPlan
+{
+    size_t layer_id { 0 };
+    size_t pass_index { 0 };
+    bool   split_interval { false };
+    double z_lo { 0.0 };
+    double z_hi { 0.0 };
+    double print_z { 0.0 };
+    double flow_height { 0.0 };
+    size_t dependency_group { 0 };
+    size_t dependency_order { 0 };
+    std::vector<ExPolygons> painted_masks_by_extruder;
+    std::vector<ExPolygons> fixed_painted_masks_by_extruder;
+    ExPolygons              base_masks;
+};
+
 enum SupportNecessaryType {
     NoNeedSupp=0,
     SharpTail,
@@ -400,6 +430,19 @@ public:
     std::shared_ptr<TreeSupportData> alloc_tree_support_preview_cache();
     void clear_tree_support_preview_cache() { m_tree_support_preview_cache.reset(); }
 
+    const std::vector<LocalZInterval>& local_z_intervals() const { return m_local_z_intervals; }
+    const std::vector<SubLayerPlan>&   local_z_sublayer_plan() const { return m_local_z_sublayer_plan; }
+    void set_local_z_plan(std::vector<LocalZInterval> intervals, std::vector<SubLayerPlan> sublayers)
+    {
+        m_local_z_intervals     = std::move(intervals);
+        m_local_z_sublayer_plan = std::move(sublayers);
+    }
+    void clear_local_z_plan()
+    {
+        m_local_z_intervals.clear();
+        m_local_z_sublayer_plan.clear();
+    }
+
     size_t          support_layer_count() const { return m_support_layers.size(); }
     void            clear_support_layers();
     SupportLayer*   get_support_layer(int idx) { return idx<m_support_layers.size()? m_support_layers[idx]:nullptr; }
@@ -410,7 +453,10 @@ public:
 
     // Initialize the layer_height_profile from the model_object's layer_height_profile, from model_object's layer height table, or from slicing parameters.
     // Returns true, if the layer_height_profile was changed.
-    static bool     update_layer_height_profile(const ModelObject &model_object, const SlicingParameters &slicing_parameters, std::vector<coordf_t> &layer_height_profile);
+    static bool     update_layer_height_profile(const ModelObject &model_object,
+                                                const SlicingParameters &slicing_parameters,
+                                                std::vector<coordf_t> &layer_height_profile,
+                                                const PrintObject *print_object = nullptr);
 
     // Collect the slicing parameters, to be used by variable layer thickness algorithm,
     // by the interactive layer height editor and by the printing process itself.
@@ -557,6 +603,8 @@ private:
     SlicingParameters                       m_slicing_params;
     LayerPtrs                               m_layers;
     SupportLayerPtrs                        m_support_layers;
+    std::vector<LocalZInterval>             m_local_z_intervals;
+    std::vector<SubLayerPlan>               m_local_z_sublayer_plan;
     // BBS
     std::shared_ptr<TreeSupportData>        m_tree_support_preview_cache;
 
@@ -752,6 +800,7 @@ struct WipeTowerData
     // Cache of tool changes per print layer.
     std::unique_ptr<std::vector<WipeTower::ToolChangeResult>> priming;
     std::vector<std::vector<WipeTower::ToolChangeResult>> tool_changes;
+    std::vector<std::vector<WipeTower::ToolChangeResult>> local_z_tool_changes;
     std::unique_ptr<WipeTower::ToolChangeResult>          final_purge;
     std::vector<float>                                    used_filament;
     int                                                   number_of_toolchanges;
@@ -764,9 +813,12 @@ struct WipeTowerData
     BoundingBoxf                                          bbx;//including brim
     Vec2f                                                 rib_offset;
     std::optional<WipeTowerMeshData>                      wipe_tower_mesh_data;//added rib_offset
+    // Per-layer boxes reserved for Local-Z unplanned toolchanges.
+    std::vector<std::vector<WipeTower::box_coordinates>>  local_z_reserve_boxes;
     void clear() {
         priming.reset(nullptr);
         tool_changes.clear();
+        local_z_tool_changes.clear();
         final_purge.reset(nullptr);
         used_filament.clear();
         number_of_toolchanges = -1;
@@ -774,6 +826,7 @@ struct WipeTowerData
         brim_width = 0.f;
         rib_offset = Vec2f::Zero();
         wipe_tower_mesh_data  = std::nullopt;
+        local_z_reserve_boxes.clear();
     }
     void construct_mesh(float width, float depth, float height, float brim_width, bool is_rib_wipe_tower, float rib_width, float rib_length, bool fillet_wall);
 
@@ -946,6 +999,8 @@ public:
     void                auto_assign_extruders(ModelObject* model_object) const;
 
     const PrintConfig&          config() const { return m_config; }
+    const MixedFilamentManager& mixed_filament_manager() const { return m_mixed_filament_mgr; }
+    MixedFilamentManager&       mixed_filament_manager()       { return m_mixed_filament_mgr; }
     const PrintObjectConfig&    default_object_config() const { return m_default_object_config; }
     const PrintRegionConfig& default_region_config() const { return m_default_region_config; }
     ConstPrintObjectPtrsAdaptor objects() const { return ConstPrintObjectPtrsAdaptor(&m_objects); }
@@ -1134,6 +1189,7 @@ private:
     Polygons            first_layer_islands() const;
 
     PrintConfig                             m_config;
+    MixedFilamentManager                    m_mixed_filament_mgr;
     PrintObjectConfig                       m_default_object_config;
     PrintRegionConfig                       m_default_region_config;
     PrintObjectPtrs                         m_objects;

src/libslic3r/PrintApply.cpp

@@ -1104,6 +1104,57 @@ static PrintObjectRegions* generate_print_object_regions(
     return out.release();
 }
 
+// ---- Mixed-filament helpers used in Print::apply ----------------------------------------
+
+static inline void append_unique_painted_extruder(std::vector<unsigned int> &painting_extruders,
+                                                  unsigned int                extruder_id,
+                                                  size_t                      num_physical_extruders)
+{
+    if (extruder_id < 1 || extruder_id > num_physical_extruders)
+        return;
+    if (std::find(painting_extruders.begin(), painting_extruders.end(), extruder_id) == painting_extruders.end())
+        painting_extruders.emplace_back(extruder_id);
+}
+
+// For a virtual (mixed) ID, expand to all physical component IDs it may resolve to.
+// This pre-creates regions for every physical tool the mixed row can use so that
+// apply_mm_segmentation can collapse mixed channels onto the correct region.
+static void append_mixed_component_extruders(const MixedFilamentManager &mixed_mgr,
+                                             unsigned int                state_id,
+                                             size_t                      num_physical_extruders,
+                                             std::vector<unsigned int>  &painting_extruders)
+{
+    if (state_id <= num_physical_extruders)
+        return;
+
+    const MixedFilament *mixed_row = mixed_mgr.mixed_filament_from_id(state_id, num_physical_extruders);
+    if (mixed_row == nullptr || !mixed_row->enabled)
+        return;
+
+    append_unique_painted_extruder(painting_extruders, mixed_row->component_a, num_physical_extruders);
+    append_unique_painted_extruder(painting_extruders, mixed_row->component_b, num_physical_extruders);
+
+    for (char token : mixed_row->gradient_component_ids) {
+        if (token < '1' || token > '9')
+            continue;
+        append_unique_painted_extruder(painting_extruders, unsigned(token - '0'), num_physical_extruders);
+    }
+
+    for (char token : mixed_row->manual_pattern) {
+        unsigned int extruder_id = 0;
+        if (token == '1')
+            extruder_id = mixed_row->component_a;
+        else if (token == '2')
+            extruder_id = mixed_row->component_b;
+        else if (token >= '3' && token <= '9')
+            extruder_id = unsigned(token - '0');
+
+        append_unique_painted_extruder(painting_extruders, extruder_id, num_physical_extruders);
+    }
+}
+
+// -----------------------------------------------------------------------------------------
+
 Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_config, bool extruder_applied)
 {
 #ifdef _DEBUG
@@ -1116,6 +1167,60 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
 	new_full_config.option("print_settings_id",            true);
 	new_full_config.option("filament_settings_id",         true);
 	new_full_config.option("printer_settings_id",          true);
+    // Ensure mixed-filament and dithering keys are present so in-session updates are detected.
+    new_full_config.option("mixed_filament_gradient_mode", true);
+    new_full_config.option("mixed_color_layer_height_a", true);
+    new_full_config.option("mixed_color_layer_height_b", true);
+    new_full_config.option("mixed_filament_height_lower_bound", true);
+    new_full_config.option("mixed_filament_height_upper_bound", true);
+    new_full_config.option("mixed_filament_advanced_dithering", true);
+    new_full_config.option("mixed_filament_pointillism_pixel_size", true);
+    new_full_config.option("mixed_filament_pointillism_line_gap", true);
+    new_full_config.option("mixed_filament_component_bias_enabled", true);
+    new_full_config.option("mixed_filament_surface_indentation", true);
+    new_full_config.option("mixed_filament_region_collapse", true);
+    new_full_config.option("mixed_filament_definitions", true);
+    new_full_config.option("dithering_z_step_size", true);
+    new_full_config.option("dithering_local_z_mode", true);
+    new_full_config.option("dithering_local_z_whole_objects", true);
+    new_full_config.option("dithering_local_z_direct_multicolor", true);
+    new_full_config.option("dithering_step_painted_zones_only", true);
+    // Materialize the same keys on m_config so print_diff sees no phantom changes on cold start.
+    m_config.option("mixed_filament_gradient_mode", true);
+    m_config.option("mixed_color_layer_height_a", true);
+    m_config.option("mixed_color_layer_height_b", true);
+    m_config.option("mixed_filament_height_lower_bound", true);
+    m_config.option("mixed_filament_height_upper_bound", true);
+    m_config.option("mixed_filament_advanced_dithering", true);
+    m_config.option("mixed_filament_pointillism_pixel_size", true);
+    m_config.option("mixed_filament_pointillism_line_gap", true);
+    m_config.option("mixed_filament_component_bias_enabled", true);
+    m_config.option("mixed_filament_surface_indentation", true);
+    m_config.option("mixed_filament_region_collapse", true);
+    m_config.option("mixed_filament_definitions", true);
+    m_config.option("dithering_z_step_size", true);
+    m_config.option("dithering_local_z_mode", true);
+    m_config.option("dithering_local_z_whole_objects", true);
+    m_config.option("dithering_local_z_direct_multicolor", true);
+    m_config.option("dithering_step_painted_zones_only", true);
+    // Materialize the same keys on m_default_object_config for symmetry.
+    m_default_object_config.option("mixed_filament_gradient_mode", true);
+    m_default_object_config.option("mixed_color_layer_height_a", true);
+    m_default_object_config.option("mixed_color_layer_height_b", true);
+    m_default_object_config.option("mixed_filament_height_lower_bound", true);
+    m_default_object_config.option("mixed_filament_height_upper_bound", true);
+    m_default_object_config.option("mixed_filament_advanced_dithering", true);
+    m_default_object_config.option("mixed_filament_pointillism_pixel_size", true);
+    m_default_object_config.option("mixed_filament_pointillism_line_gap", true);
+    m_default_object_config.option("mixed_filament_component_bias_enabled", true);
+    m_default_object_config.option("mixed_filament_surface_indentation", true);
+    m_default_object_config.option("mixed_filament_region_collapse", true);
+    m_default_object_config.option("mixed_filament_definitions", true);
+    m_default_object_config.option("dithering_z_step_size", true);
+    m_default_object_config.option("dithering_local_z_mode", true);
+    m_default_object_config.option("dithering_local_z_whole_objects", true);
+    m_default_object_config.option("dithering_local_z_direct_multicolor", true);
+    m_default_object_config.option("dithering_step_painted_zones_only", true);
 
     // BBS
     std::vector <unsigned int> used_filaments = this->extruders(true);
@@ -1281,6 +1386,87 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
         }
     }
 
+    // Rebuild the mixed (virtual) filament manager from physical colours and user-defined
+    // custom entries.  This must happen after m_config is up-to-date so filament_colour
+    // reflects the correct physical palette.
+    {
+        int   mixed_gradient_mode = 0;
+        float mixed_height_lower  = 0.04f;
+        float mixed_height_upper  = 0.16f;
+        bool  mixed_advanced_dither = false;
+        float mixed_pointillism_pixel_size = 0.f;
+        float mixed_pointillism_line_gap   = 0.f;
+        float mixed_surface_indentation = 0.f;
+        std::string mixed_custom_definitions;
+
+        if (new_full_config.has("mixed_filament_gradient_mode")) {
+            if (const ConfigOptionBool *opt = new_full_config.option<ConfigOptionBool>("mixed_filament_gradient_mode"))
+                mixed_gradient_mode = opt->value ? 1 : 0;
+            else
+                mixed_gradient_mode = new_full_config.opt_int("mixed_filament_gradient_mode");
+        }
+        if (new_full_config.has("mixed_filament_height_lower_bound"))
+            mixed_height_lower = float(new_full_config.opt_float("mixed_filament_height_lower_bound"));
+        if (new_full_config.has("mixed_filament_height_upper_bound"))
+            mixed_height_upper = float(new_full_config.opt_float("mixed_filament_height_upper_bound"));
+        if (new_full_config.has("mixed_filament_advanced_dithering")) {
+            if (const ConfigOptionBool *opt = new_full_config.option<ConfigOptionBool>("mixed_filament_advanced_dithering"))
+                mixed_advanced_dither = opt->value;
+            else
+                mixed_advanced_dither = (new_full_config.opt_int("mixed_filament_advanced_dithering") != 0);
+        }
+        if (new_full_config.has("mixed_filament_pointillism_pixel_size"))
+            mixed_pointillism_pixel_size = float(new_full_config.opt_float("mixed_filament_pointillism_pixel_size"));
+        if (new_full_config.has("mixed_filament_pointillism_line_gap"))
+            mixed_pointillism_line_gap = float(new_full_config.opt_float("mixed_filament_pointillism_line_gap"));
+        if (new_full_config.has("mixed_filament_surface_indentation"))
+            mixed_surface_indentation = float(new_full_config.opt_float("mixed_filament_surface_indentation"));
+        if (new_full_config.has("mixed_filament_definitions"))
+            mixed_custom_definitions = new_full_config.opt_string("mixed_filament_definitions");
+
+        mixed_gradient_mode = std::clamp(mixed_gradient_mode, 0, 1);
+        mixed_height_lower  = std::max(0.01f, mixed_height_lower);
+        mixed_height_upper  = std::max(mixed_height_lower, mixed_height_upper);
+        mixed_pointillism_pixel_size = std::max(0.f, mixed_pointillism_pixel_size);
+        mixed_pointillism_line_gap   = std::max(0.f, mixed_pointillism_line_gap);
+        mixed_surface_indentation = std::clamp(mixed_surface_indentation, -2.f, 2.f);
+
+        BOOST_LOG_TRIVIAL(info) << "Print::apply mixed settings"
+                                << ", gradient_mode=" << mixed_gradient_mode
+                                << ", lower=" << mixed_height_lower
+                                << ", upper=" << mixed_height_upper
+                                << ", advanced_dither=" << (mixed_advanced_dither ? 1 : 0)
+                                << ", pointillism_pixel_size=" << mixed_pointillism_pixel_size
+                                << ", pointillism_line_gap=" << mixed_pointillism_line_gap
+                                << ", surface_indentation=" << mixed_surface_indentation
+                                << ", custom_definitions_len=" << mixed_custom_definitions.size()
+                                << ", physical_extruders=" << num_extruders;
+
+        // Regenerate mixed (virtual) filaments from physical filament colours and
+        // re-apply user custom mixed definitions.
+        std::vector<std::string> physical_filament_colors = m_config.filament_colour.values;
+        physical_filament_colors.resize(num_extruders, "#26A69A");
+        m_mixed_filament_mgr.clear_custom_entries();
+        m_mixed_filament_mgr.auto_generate(physical_filament_colors);
+        m_mixed_filament_mgr.load_custom_entries(mixed_custom_definitions, physical_filament_colors);
+        m_mixed_filament_mgr.apply_gradient_settings(mixed_gradient_mode,
+                                                     mixed_height_lower,
+                                                     mixed_height_upper,
+                                                     mixed_advanced_dither);
+        size_t mixed_custom_count = 0;
+        for (const auto &mf : m_mixed_filament_mgr.mixed_filaments())
+            if (mf.custom)
+                ++mixed_custom_count;
+
+        BOOST_LOG_TRIVIAL(info) << "Print::apply mixed manager state"
+                                << ", mixed_total=" << m_mixed_filament_mgr.mixed_filaments().size()
+                                << ", mixed_enabled=" << m_mixed_filament_mgr.enabled_count()
+                                << ", mixed_custom=" << mixed_custom_count;
+    }
+    // Total filaments = physical extruders + enabled mixed (virtual) filaments.
+    // Used for extruder ID clamping so that virtual IDs are accepted.
+    const size_t num_total_filaments = m_mixed_filament_mgr.total_filaments(num_extruders);
+
     ModelObjectStatusDB model_object_status_db;
 
     // 1) Synchronize model objects.
@@ -1468,7 +1654,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
 			if (object_config_changed)
 				model_object.config.assign_config(model_object_new.config);
             if (! object_diff.empty() || object_config_changed || num_extruders_changed ) {
-                PrintObjectConfig new_config = PrintObject::object_config_from_model_object(m_default_object_config, model_object, num_extruders );
+                PrintObjectConfig new_config = PrintObject::object_config_from_model_object(m_default_object_config, model_object, num_total_filaments);
                 for (const PrintObjectStatus &print_object_status : print_object_status_db.get_range(model_object)) {
                     t_config_option_keys diff = print_object_status.print_object->config().diff(new_config);
                     if (! diff.empty()) {
@@ -1534,10 +1720,10 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
             // Generate a list of trafos and XY offsets for instances of a ModelObject
             // Producing the config for PrintObject on demand, caching it at print_object_last.
             const PrintObject *print_object_last = nullptr;
-            auto print_object_apply_config = [this, &print_object_last, model_object, num_extruders ](PrintObject *print_object) {
+            auto print_object_apply_config = [this, &print_object_last, model_object, num_total_filaments](PrintObject *print_object) {
                 print_object->config_apply(print_object_last ?
                     print_object_last->config() :
-                    PrintObject::object_config_from_model_object(m_default_object_config, *model_object, num_extruders ));
+                    PrintObject::object_config_from_model_object(m_default_object_config, *model_object, num_total_filaments));
                 print_object_last = print_object;
             };
             if (old.empty()) {
@@ -1675,17 +1861,24 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
             std::array<bool, static_cast<size_t>(EnforcerBlockerType::ExtruderMax) + 1> used_facet_states{};
             for (const ModelVolume *volume : volumes) {
                 const std::vector<bool> &volume_used_facet_states = volume->mmu_segmentation_facets.get_data().used_states;
-
-                assert(volume_used_facet_states.size() == used_facet_states.size());
                 for (size_t state_idx = 0; state_idx < std::min(volume_used_facet_states.size(), used_facet_states.size()); ++state_idx)
                     used_facet_states[state_idx] |= volume_used_facet_states[state_idx];
             }
 
             for (size_t state_idx = static_cast<size_t>(EnforcerBlockerType::Extruder1); state_idx < used_facet_states.size(); ++state_idx) {
-                if (used_facet_states[state_idx])
-                    painting_extruders.emplace_back(state_idx);
+                if (!used_facet_states[state_idx])
+                    continue;
+                if (state_idx <= num_total_filaments) {
+                    painting_extruders.emplace_back(static_cast<unsigned int>(state_idx));
+                    append_mixed_component_extruders(m_mixed_filament_mgr,
+                                                     static_cast<unsigned int>(state_idx),
+                                                     num_extruders,
+                                                     painting_extruders);
                 }
             }
+            std::sort(painting_extruders.begin(), painting_extruders.end());
+            painting_extruders.erase(std::unique(painting_extruders.begin(), painting_extruders.end()), painting_extruders.end());
+        }
         if (model_object_status.print_object_regions_status == ModelObjectStatus::PrintObjectRegionsStatus::Valid) {
             // Verify that the trafo for regions & volume bounding boxes thus for regions is still applicable.
             auto invalidate = [it_print_object, it_print_object_end, update_apply_status]() {
@@ -1702,7 +1895,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                 verify_update_print_object_regions(
                     print_object.model_object()->volumes,
                     m_default_region_config,
-                    num_extruders,
+                    num_total_filaments,
                     *print_object_regions,
                     [it_print_object, it_print_object_end, &update_apply_status](const PrintRegionConfig &old_config, const PrintRegionConfig &new_config, const t_config_option_keys &diff_keys) {
                         for (auto it = it_print_object; it != it_print_object_end; ++it)
@@ -1727,7 +1920,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
                 LayerRanges(print_object.model_object()->layer_config_ranges),
                 m_default_region_config,
                 model_object_status.print_instances.front().trafo,
-                num_extruders ,
+                num_total_filaments,
                 print_object.is_mm_painted() ? 0.f : float(print_object.config().xy_contour_compensation.value),
                 painting_extruders,
                 print_object.is_fuzzy_skin_painted());

src/libslic3r/PrintConfig.cpp

@@ -2404,6 +2404,177 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionStrings{ "#F2754E" });
 
+    def = this->add("mixed_color_layer_height_a", coFloat);
+    def->label = L("Dithering cadence height A");
+    def->category = L("Others");
+    def->tooltip = L("Layer height contribution of component A for dithering virtual filaments. "
+                     "Set to 0 to use normal 1-layer A / 1-layer B alternation.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->sidetext = "mm";
+    def->min = 0.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("mixed_color_layer_height_b", coFloat);
+    def->label = L("Dithering cadence height B");
+    def->category = L("Others");
+    def->tooltip = L("Layer height contribution of component B for dithering virtual filaments. "
+                     "Set to 0 to use normal 1-layer A / 1-layer B alternation.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->sidetext = "mm";
+    def->min = 0.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("mixed_filament_gradient_mode", coBool);
+    def->label = L("Height-weighted cadence");
+    def->category = L("Others");
+    def->tooltip = L("Enable height-weighted cadence for mixed filaments. "
+                     "Limitation: only one height-weighted mixed color should be present at a given Z plane, "
+                     "because independent per-color layer heights are not supported and the resulting layer height applies to the whole plane. "
+                     "When disabled, layer-cycle cadence is used.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("mixed_filament_height_lower_bound", coFloat);
+    def->label = L("Local-Z lower height bound");
+    def->category = L("Others");
+    def->tooltip = L("Lower bound used when Local-Z mixed-filament dithering chooses per-color sublayer heights.\n\n"
+                     "Smaller values let Local-Z use thinner sublayers for a color when needed.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->sidetext = "mm";
+    def->min = 0.01;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.04));
+
+    def = this->add("mixed_filament_height_upper_bound", coFloat);
+    def->label = L("Local-Z upper height bound");
+    def->category = L("Others");
+    def->tooltip = L("Upper bound used when Local-Z mixed-filament dithering chooses per-color sublayer heights.\n\n"
+                     "Larger values let Local-Z use thicker sublayers for a color when needed.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->sidetext = "mm";
+    def->min = 0.01;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.16));
+
+    def = this->add("mixed_filament_advanced_dithering", coBool);
+    def->label = L("Advanced dithering");
+    def->category = L("Others");
+    def->tooltip = L("Distribute mixed filament layer-cycle cadence using an advanced ordered dithering pattern "
+                     "instead of a simple contiguous A-then-B run. This can reduce visible striping for some hues.\n\n"
+                     "This is an even more experimental mode and the perceived color may differ from normal dithering "
+                     "for the same filament pair and ratio.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("mixed_filament_component_bias_enabled", coBool);
+    def->label = L("Enable mixed filament bias");
+    def->category = L("Others");
+    def->tooltip = L("Show and apply the per-row mixed filament Bias control.\n\n"
+                     "When enabled, the selected filament in a mixed pair is recessed slightly so the other component becomes more visible.\n\n"
+                     "Bias is ignored for grouped wall patterns, same-layer pointillisme, and Local Z dithering.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("mixed_filament_surface_indentation", coFloat);
+    def->label = L("Selective Expansion contraction");
+    def->category = L("Others");
+    def->tooltip = L("XY offset applied to mixed-filament painted regions before region assignment.\n\n"
+                     "Positive values contract the mixed zone inward. Negative values expand it outward.\n\n"
+                     "This applies to mixed filament usage in layer cadence, height cadence, same-layer pointillisme, and local Z dithering.");
+    def->sidetext = "mm";
+    def->min = -2.0;
+    def->max = 2.0;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("mixed_filament_region_collapse", coBool);
+    def->label = L("Collapse same-color mixed regions");
+    def->category = L("Others");
+    def->tooltip = L("Merge ordinary mixed-filament painted regions into a single area when they resolve to the same physical filament on a layer.\n\n"
+                     "This improves continuity for adjacent same-color areas. Local Z dithering turns this off automatically when enabled, but you may turn it back on manually.\n\n"
+                     "Experimental with Local Z dithering.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(true));
+
+    def = this->add("mixed_filament_definitions", coString);
+    def->label = L("Mixed filament custom definitions");
+    def->tooltip = L("Serialized custom mixed filament rows.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->gui_flags = "serialized";
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionString(""));
+
+    def = this->add("mixed_filament_pointillism_pixel_size", coFloat);
+    def->label = L("Pointillisme pixel size");
+    def->category = L("Others");
+    def->tooltip = L("Length of one pointillisme segment along an extrusion path for same-layer pointillisme mode. "
+                     "Set to 0 to use automatic nozzle-based sizing.\n\n"
+                     "Warning: Same-layer pointillisme is extremely experimental and may produce unusable results.");
+    def->sidetext = "mm";
+    def->min = 0.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("mixed_filament_pointillism_line_gap", coFloat);
+    def->label = L("Pointillisme line gap");
+    def->category = L("Others");
+    def->tooltip = L("Optional non-extruded spacing between adjacent pointillisme segments. "
+                     "Increase carefully to improve separation and print quality.\n\n"
+                     "Warning: Same-layer pointillisme is extremely experimental and may produce unusable results.");
+    def->sidetext = "mm";
+    def->min = 0.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("dithering_z_step_size", coFloat);
+    def->label = L("Dithering Z step size");
+    def->category = L("Others");
+    def->tooltip = L("Layer height used in Z zones painted with dithering (mixed virtual filaments). "
+                     "Set to 0 to keep normal layer height in those zones.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->sidetext = "mm";
+    def->min = 0.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(0.0));
+
+    def = this->add("dithering_local_z_mode", coBool);
+    def->label = L("Local Z dithering mode");
+    def->category = L("Others");
+    def->tooltip = L("Use Variable Layers for Color Blending\n\n"
+                     "Blend colors by varying layer heights instead of using a fixed ratio of equal-height layers. This only affects blended color zones; non-blended areas keep their nominal layer height and cadence when possible.\n\n"
+                     "This setting increases color blending smoothness by splitting each blended layer according to the blend ratio. For example, a 66/33 blend at 0.12 mm layer height will print as one 0.08 mm layer and one 0.04 mm layer. At 0.20 mm layer height, a 75/25 blend will print as one 0.15 mm layer and one 0.05 mm layer.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("dithering_local_z_whole_objects", coBool);
+    def->label = L("Apply Local-Z to whole mixed objects");
+    def->category = L("Others");
+    def->tooltip = L("Experimental. Extend Local-Z dithering beyond painted mixed zones so mixed wall regions can use Local-Z across the whole object.\n\n"
+                     "This also lets Local-Z continue through default mixed walls around painted areas instead of limiting the effect strictly to painted masks.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("dithering_local_z_direct_multicolor", coBool);
+    def->label = L("Use direct multicolor Local-Z solver");
+    def->category = L("Others");
+    def->tooltip = L("Experimental. For mixed rows with 3 or more physical filaments, allocate Local-Z sublayers directly across all components with carry-over error between layers instead of collapsing them into pair cadence.\n\n"
+                     "This can reduce visible banding in multicolor Local-Z blends at the cost of more toolchanges. It is ignored when explicit Local-Z A/B heights are set.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("dithering_step_painted_zones_only", coBool);
+    def->label = L("Use step size in painted zones only");
+    def->category = L("Others");
+    def->tooltip = L("When enabled, dithering Z step size is applied only where mixed filament is painted. "
+                     "Unpainted zones keep their original layer height.\n\n"
+                     "Detailed mixed filament setting explanations will be published once the project wiki is available.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(true));
+
     // PS
     def = this->add("filament_notes", coStrings);
     def->label = L("Filament notes");
@@ -4077,6 +4248,31 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionInt(0));
 
+    def = this->add("enable_infill_filament_override", coBool);
+    def->label = L("Override infill filament");
+    def->category = L("Extruders");
+    def->tooltip = L("Allow this print, object, or part to use a dedicated filament for sparse infill instead of inheriting its regular filament.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("infill_filament_use_base_first_layers", coInt);
+    def->label = L("Base infill on first layers");
+    def->category = L("Extruders");
+    def->tooltip = L("Keep using the regular object filament for this many bottom infill layers before switching to the infill override filament.");
+    def->sidetext = L("layers");
+    def->min = 0;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionInt(0));
+
+    def = this->add("infill_filament_use_base_last_layers", coInt);
+    def->label = L("Base infill on last layers");
+    def->category = L("Extruders");
+    def->tooltip = L("Keep using the regular object filament for this many top infill layers after switching back from the infill override filament.");
+    def->sidetext = L("layers");
+    def->min = 0;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionInt(0));
+
     def = this->add("sparse_infill_line_width", coFloatOrPercent);
     def->label = L("Sparse infill");
     def->category = L("Quality");
@@ -6959,6 +7155,16 @@ void PrintConfigDef::init_fff_params()
     def->max = 300.;
     def->set_default_value(new ConfigOptionPercent(100.));
 
+    def = this->add("local_z_wipe_tower_purge_lines", coFloat);
+    def->label = L("Local-Z mini wipe lines");
+    def->tooltip = L("Number of purge lines reserved for each runtime Local-Z wipe tower toolchange. "
+                     "Higher values improve cleanup but increase tower depth. "
+                     "Only used when Local-Z dithering and the prime tower are enabled.");
+    def->sidetext = L("lines");
+    def->mode = comAdvanced;
+    def->min = 1.0;
+    def->set_default_value(new ConfigOptionFloat(3.0));
+
     def = this->add("idle_temperature", coInts);
     def->label = L("Idle temperature");
     def->tooltip = L("Nozzle temperature when the tool is currently not used in multi-tool setups. "
@@ -8571,6 +8777,23 @@ t_config_option_keys DynamicPrintConfig::normalize_fdm_2(int num_objects, int us
         */
     }
 
+    // Mixed-filament lifecycle anchor.
+    // Side-effect: PresetBundle observes the mixed_filament_definitions string change and rebuilds the manager
+    // (see PresetBundle::sync_mixed_filaments_from_config). Nothing to do here —
+    // keep this comment as a lifecycle anchor for future maintainers.
+    if (auto* defs = this->option<ConfigOptionString>("mixed_filament_definitions")) {
+        (void)defs;
+    }
+
+    // Backward-compat: if an older project set sparse_infill_filament to a non-wall value
+    // but did not set enable_infill_filament_override, infer the flag.
+    if (!this->has("enable_infill_filament_override") && this->has("sparse_infill_filament")) {
+        int wall   = this->has("wall_filament") ? this->opt_int("wall_filament") : 1;
+        int sparse = this->opt_int("sparse_infill_filament");
+        if (sparse > 0 && sparse != wall)
+            this->set_key_value("enable_infill_filament_override", new ConfigOptionBool(true));
+    }
+
     return changed_keys;
 }
 

src/libslic3r/PrintConfig.hpp

@@ -1121,6 +1121,9 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionPercent,              fuzzy_skin_ripple_offset))
     ((ConfigOptionInt,                  fuzzy_skin_layers_between_ripple_offset))
     ((ConfigOptionFloat,                gap_infill_speed))
+    ((ConfigOptionBool,                 enable_infill_filament_override))
+    ((ConfigOptionInt,                  infill_filament_use_base_first_layers))
+    ((ConfigOptionInt,                  infill_filament_use_base_last_layers))
     ((ConfigOptionInt,                  sparse_infill_filament))
     ((ConfigOptionFloatOrPercent,       sparse_infill_line_width))
     ((ConfigOptionPercent,              infill_wall_overlap))
@@ -1551,6 +1554,23 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     ((ConfigOptionBool,               ooze_prevention))
     ((ConfigOptionString,             filename_format))
     ((ConfigOptionStrings,            post_process))
+    ((ConfigOptionFloat,              mixed_color_layer_height_a))
+    ((ConfigOptionFloat,              mixed_color_layer_height_b))
+    ((ConfigOptionBool,               mixed_filament_gradient_mode))
+    ((ConfigOptionFloat,              mixed_filament_height_lower_bound))
+    ((ConfigOptionFloat,              mixed_filament_height_upper_bound))
+    ((ConfigOptionBool,               mixed_filament_advanced_dithering))
+    ((ConfigOptionBool,               mixed_filament_component_bias_enabled))
+    ((ConfigOptionFloat,              mixed_filament_surface_indentation))
+    ((ConfigOptionBool,               mixed_filament_region_collapse))
+    ((ConfigOptionString,             mixed_filament_definitions))
+    ((ConfigOptionFloat,              mixed_filament_pointillism_pixel_size))
+    ((ConfigOptionFloat,              mixed_filament_pointillism_line_gap))
+    ((ConfigOptionFloat,              dithering_z_step_size))
+    ((ConfigOptionBool,               dithering_local_z_mode))
+    ((ConfigOptionBool,               dithering_local_z_whole_objects))
+    ((ConfigOptionBool,               dithering_local_z_direct_multicolor))
+    ((ConfigOptionBool,               dithering_step_painted_zones_only))
     ((ConfigOptionString,             printer_model))
     ((ConfigOptionFloat,              resolution))
     ((ConfigOptionFloats,             retraction_minimum_travel))
@@ -1593,6 +1613,7 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     ((ConfigOptionBool,               enable_tower_interface_cooldown_during_tower))
     ((ConfigOptionFloat,              wipe_tower_bridging))
     ((ConfigOptionPercent,            wipe_tower_extra_flow))
+    ((ConfigOptionFloat,              local_z_wipe_tower_purge_lines))
     ((ConfigOptionFloats,             flush_volumes_matrix))
     ((ConfigOptionFloats,             flush_volumes_vector))
 

src/libslic3r/PrintObject.cpp

@@ -992,6 +992,7 @@ FillLightning::GeneratorPtr PrintObject::prepare_lightning_infill_data()
 
 void PrintObject::clear_layers()
 {
+    this->clear_local_z_plan();
     if (!m_shared_object) {
         for (Layer *l : m_layers)
             delete l;
@@ -1138,6 +1139,13 @@ bool PrintObject::invalidate_state_by_config_options(
             steps.emplace_back(posPerimeters);
         } else if (
                opt_key == "layer_height"
+            || opt_key == "dithering_z_step_size"
+            || opt_key == "dithering_local_z_mode"
+            || opt_key == "dithering_local_z_whole_objects"
+            || opt_key == "dithering_local_z_direct_multicolor"
+            || opt_key == "dithering_step_painted_zones_only"
+            || opt_key == "mixed_filament_component_bias_enabled"
+            || opt_key == "mixed_filament_region_collapse"
             || opt_key == "mmu_segmented_region_max_width"
             || opt_key == "mmu_segmented_region_interlocking_depth"
             || opt_key == "raft_layers"
@@ -1154,6 +1162,19 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "interlocking_depth"
             || opt_key == "interlocking_boundary_avoidance"
             || opt_key == "interlocking_beam_width") {
+            steps.emplace_back(posSlice);
+        } else if (
+               opt_key == "mixed_filament_gradient_mode"
+            || opt_key == "mixed_filament_height_lower_bound"
+            || opt_key == "mixed_filament_height_upper_bound"
+            || opt_key == "mixed_filament_advanced_dithering"
+            || opt_key == "mixed_filament_component_bias_enabled"
+            || opt_key == "mixed_filament_surface_indentation"
+            || opt_key == "mixed_filament_region_collapse"
+            || opt_key == "mixed_filament_definitions") {
+            // Mixed filament gradient controls affect layer cadence and virtual
+            // tool distribution, so force a re-slice prompt like other
+            // layer-structure settings.
             steps.emplace_back(posSlice);
 		} else if (
                opt_key == "elefant_foot_compensation"
@@ -1450,6 +1471,7 @@ bool PrintObject::invalidate_step(PrintObjectStep step)
 		invalidated |= this->invalidate_steps({ posPerimeters, posPrepareInfill, posInfill, posIroning, posContouring, posSupportMaterial, posSimplifyPath, posSimplifyInfill });
         invalidated |= m_print->invalidate_steps({ psSkirtBrim });
         m_slicing_params.valid = false;
+        this->clear_local_z_plan();
     } else if (step == posSupportMaterial) {
         invalidated |= this->invalidate_steps({ posSimplifySupportPath });
         invalidated |= m_print->invalidate_steps({ psSkirtBrim });
@@ -1471,6 +1493,7 @@ bool PrintObject::invalidate_all_steps()
     bool result = Inherited::invalidate_all_steps() | m_print->invalidate_all_steps();
 	// Then reset some of the depending values.
 	m_slicing_params.valid = false;
+    this->clear_local_z_plan();
 	return result;
 }
 
@@ -3555,7 +3578,8 @@ static void apply_to_print_region_config(PrintRegionConfig &out, const DynamicPr
         if (it->first != key_extruder)
             if (ConfigOption* my_opt = out.option(it->first, false); my_opt != nullptr) {
                 if (one_of(it->first, keys_extruders)) {
-                    // "Default" (0) clears explicit override for this scope and lets fallback apply.
+                    // "Default" (0) keeps any prior explicit feature override from parent scopes.
+                    // This lets object/part base filament be the default unless an explicit feature filament was chosen.
                     int extruder = static_cast<const ConfigOptionInt*>(it->second.get())->value;
                     if (extruder > 0) {
                         my_opt->setInt(extruder);
@@ -3565,13 +3589,6 @@ static void apply_to_print_region_config(PrintRegionConfig &out, const DynamicPr
                             feature_overrides.solid_infill_filament = true;
                         else if (it->first == "wall_filament")
                             feature_overrides.wall_filament = true;
-                    } else {
-                        if (it->first == "sparse_infill_filament")
-                            feature_overrides.sparse_infill_filament = false;
-                        else if (it->first == "solid_infill_filament")
-                            feature_overrides.solid_infill_filament = false;
-                        else if (it->first == "wall_filament")
-                            feature_overrides.wall_filament = false;
                     }
                 } else
                     my_opt->set(it->second.get());
@@ -3720,16 +3737,564 @@ std::vector<unsigned int> PrintObject::object_extruders() const
     return extruders;
 }
 
-bool PrintObject::update_layer_height_profile(const ModelObject &model_object, const SlicingParameters &slicing_parameters, std::vector<coordf_t> &layer_height_profile)
+namespace {
+
+struct LayerHeightRangeOverride {
+    coordf_t lo { 0.f };
+    coordf_t hi { 0.f };
+    coordf_t height { 0.f };
+};
+
+struct MixedStateZRanges {
+    size_t state_id { 0 };
+    std::vector<t_layer_height_range> ranges;
+};
+
+struct MixedStateCadence {
+    size_t state_id { 0 };
+    coordf_t height_a { 0.f };
+    coordf_t height_b { 0.f };
+    std::vector<t_layer_height_range> ranges;
+};
+
+static void sort_and_merge_layer_ranges(std::vector<t_layer_height_range> &ranges)
+{
+    if (ranges.empty())
+        return;
+
+    std::sort(ranges.begin(), ranges.end(), [](const t_layer_height_range &a, const t_layer_height_range &b) {
+        return a.first < b.first || (a.first == b.first && a.second < b.second);
+    });
+
+    std::vector<t_layer_height_range> merged;
+    merged.reserve(ranges.size());
+    for (const t_layer_height_range &range : ranges) {
+        if (range.second <= range.first + EPSILON)
+            continue;
+
+        if (merged.empty() || range.first > merged.back().second + EPSILON) {
+            merged.emplace_back(range);
+        } else {
+            merged.back().second = std::max(merged.back().second, range.second);
+        }
+    }
+    ranges = std::move(merged);
+}
+
+static std::vector<t_layer_height_range> collect_mixed_painted_z_ranges(const PrintObject &print_object, coordf_t object_height)
+{
+    std::vector<t_layer_height_range> mixed_ranges;
+    const Print *print = print_object.print();
+    if (object_height <= EPSILON || print == nullptr)
+        return mixed_ranges;
+
+    const size_t num_physical = print->config().filament_colour.size();
+    const size_t num_total    = print->mixed_filament_manager().total_filaments(num_physical);
+    if (num_total <= num_physical)
+        return mixed_ranges;
+
+    const size_t max_state = std::min(num_total, size_t(EnforcerBlockerType::ExtruderMax));
+    std::vector<std::vector<t_layer_height_range>> per_state(max_state + 1);
+    const Transform3d object_to_print = print_object.trafo_centered();
+
+    for (const ModelVolume *mv : print_object.model_object()->volumes) {
+        if (mv == nullptr || !mv->is_model_part() || mv->mmu_segmentation_facets.empty())
+            continue;
+
+        const auto &used_states = mv->mmu_segmentation_facets.get_data().used_states;
+        if (used_states.empty())
+            continue;
+
+        const Transform3d volume_to_print = object_to_print * mv->get_matrix();
+        constexpr coordf_t thin_band = 0.01f;
+        for (size_t state_idx = num_physical + 1; state_idx <= max_state; ++state_idx) {
+            if (state_idx >= used_states.size() || !used_states[state_idx])
+                continue;
+
+            const auto facets = mv->mmu_segmentation_facets.get_facets_strict(*mv, static_cast<EnforcerBlockerType>(state_idx));
+            if (facets.indices.empty() || facets.vertices.empty())
+                continue;
+
+            auto &state_ranges = per_state[state_idx];
+            for (const auto &face : facets.indices) {
+                double tri_z_min = DBL_MAX;
+                double tri_z_max = -DBL_MAX;
+                for (int i = 0; i < 3; ++i) {
+                    const size_t vertex_idx = size_t(face[i]);
+                    if (vertex_idx >= facets.vertices.size())
+                        continue;
+                    const Vec3d p = volume_to_print * facets.vertices[vertex_idx].cast<double>();
+                    tri_z_min = std::min(tri_z_min, p.z());
+                    tri_z_max = std::max(tri_z_max, p.z());
+                }
+
+                if (tri_z_min == DBL_MAX || tri_z_max == -DBL_MAX)
+                    continue;
+
+                coordf_t lo = std::max<coordf_t>(0.f, coordf_t(tri_z_min));
+                coordf_t hi = std::min<coordf_t>(object_height, coordf_t(tri_z_max));
+                if (hi <= lo + EPSILON) {
+                    const coordf_t center = std::max<coordf_t>(0.f, std::min<coordf_t>(object_height, lo));
+                    lo = std::max<coordf_t>(0.f, center - thin_band * 0.5f);
+                    hi = std::min<coordf_t>(object_height, center + thin_band * 0.5f);
+                }
+                if (lo + EPSILON < hi)
+                    state_ranges.emplace_back(lo, hi);
+            }
+        }
+    }
+
+    for (size_t state_idx = num_physical + 1; state_idx <= max_state; ++state_idx) {
+        auto &state_ranges = per_state[state_idx];
+        if (state_ranges.empty())
+            continue;
+        sort_and_merge_layer_ranges(state_ranges);
+        mixed_ranges.insert(mixed_ranges.end(), state_ranges.begin(), state_ranges.end());
+    }
+
+    sort_and_merge_layer_ranges(mixed_ranges);
+    return mixed_ranges;
+}
+
+static std::vector<MixedStateZRanges> collect_mixed_painted_z_ranges_by_state(const PrintObject &print_object, coordf_t object_height)
+{
+    std::vector<MixedStateZRanges> out;
+    const Print *print = print_object.print();
+    if (object_height <= EPSILON || print == nullptr)
+        return out;
+
+    const size_t num_physical = print->config().filament_colour.size();
+    const size_t num_total    = print->mixed_filament_manager().total_filaments(num_physical);
+    if (num_total <= num_physical)
+        return out;
+
+    const size_t max_state = std::min(num_total, size_t(EnforcerBlockerType::ExtruderMax));
+    std::vector<std::vector<t_layer_height_range>> per_state(max_state + 1);
+    const Transform3d object_to_print = print_object.trafo_centered();
+
+    for (const ModelVolume *mv : print_object.model_object()->volumes) {
+        if (mv == nullptr || !mv->is_model_part() || mv->mmu_segmentation_facets.empty())
+            continue;
+
+        const auto &used_states = mv->mmu_segmentation_facets.get_data().used_states;
+        if (used_states.empty())
+            continue;
+
+        const Transform3d volume_to_print = object_to_print * mv->get_matrix();
+        constexpr coordf_t thin_band = 0.01f;
+        for (size_t state_idx = num_physical + 1; state_idx <= max_state; ++state_idx) {
+            if (state_idx >= used_states.size() || !used_states[state_idx])
+                continue;
+
+            const auto facets = mv->mmu_segmentation_facets.get_facets_strict(*mv, static_cast<EnforcerBlockerType>(state_idx));
+            if (facets.indices.empty() || facets.vertices.empty())
+                continue;
+
+            auto &state_ranges = per_state[state_idx];
+            for (const auto &face : facets.indices) {
+                double tri_z_min = DBL_MAX;
+                double tri_z_max = -DBL_MAX;
+                for (int i = 0; i < 3; ++i) {
+                    const size_t vertex_idx = size_t(face[i]);
+                    if (vertex_idx >= facets.vertices.size())
+                        continue;
+                    const Vec3d p = volume_to_print * facets.vertices[vertex_idx].cast<double>();
+                    tri_z_min = std::min(tri_z_min, p.z());
+                    tri_z_max = std::max(tri_z_max, p.z());
+                }
+
+                if (tri_z_min == DBL_MAX || tri_z_max == -DBL_MAX)
+                    continue;
+
+                coordf_t lo = std::max<coordf_t>(0.f, coordf_t(tri_z_min));
+                coordf_t hi = std::min<coordf_t>(object_height, coordf_t(tri_z_max));
+                if (hi <= lo + EPSILON) {
+                    const coordf_t center = std::max<coordf_t>(0.f, std::min<coordf_t>(object_height, lo));
+                    lo = std::max<coordf_t>(0.f, center - thin_band * 0.5f);
+                    hi = std::min<coordf_t>(object_height, center + thin_band * 0.5f);
+                }
+                if (lo + EPSILON < hi)
+                    state_ranges.emplace_back(lo, hi);
+            }
+        }
+    }
+
+    out.reserve(max_state > num_physical ? max_state - num_physical : 0);
+    for (size_t state_idx = num_physical + 1; state_idx <= max_state; ++state_idx) {
+        auto &state_ranges = per_state[state_idx];
+        if (state_ranges.empty())
+            continue;
+        sort_and_merge_layer_ranges(state_ranges);
+        if (!state_ranges.empty())
+            out.push_back({ state_idx, std::move(state_ranges) });
+    }
+    return out;
+}
+
+static std::vector<LayerHeightRangeOverride> base_layer_height_overrides(const t_layer_config_ranges &ranges, coordf_t object_height)
+{
+    std::vector<LayerHeightRangeOverride> out;
+    out.reserve(ranges.size());
+
+    coordf_t last_hi = 0.f;
+    for (const auto &[range, config] : ranges) {
+        coordf_t lo = std::max(range.first, last_hi);
+        coordf_t hi = std::min(range.second, object_height);
+        if (lo + EPSILON >= hi)
+            continue;
+
+        const ConfigOption *layer_height_opt = config.option("layer_height");
+        if (layer_height_opt == nullptr)
+            continue;
+
+        out.push_back({ lo, hi, coordf_t(layer_height_opt->getFloat()) });
+        last_hi = hi;
+    }
+    return out;
+}
+
+static bool contains_z(const std::vector<t_layer_height_range> &ranges, coordf_t z)
+{
+    for (const t_layer_height_range &range : ranges) {
+        if (z + EPSILON < range.first)
+            break;
+        if (z + EPSILON >= range.first && z < range.second - EPSILON)
+            return true;
+    }
+    return false;
+}
+
+static bool get_override_height(const std::vector<LayerHeightRangeOverride> &ranges, coordf_t z, coordf_t &height_out)
+{
+    for (const LayerHeightRangeOverride &range : ranges) {
+        if (z + EPSILON < range.lo)
+            break;
+        if (z + EPSILON >= range.lo && z < range.hi - EPSILON) {
+            height_out = range.height;
+            return true;
+        }
+    }
+    return false;
+}
+
+static t_layer_config_ranges layer_ranges_with_dithering(const t_layer_config_ranges &base_ranges_map,
+                                                         coordf_t                     object_height,
+                                                         coordf_t                     default_layer_height,
+                                                         const std::vector<t_layer_height_range> &mixed_ranges,
+                                                         coordf_t                     dithering_step)
+{
+    if (object_height <= EPSILON || mixed_ranges.empty() || dithering_step <= EPSILON)
+        return base_ranges_map;
+
+    const std::vector<LayerHeightRangeOverride> base_ranges = base_layer_height_overrides(base_ranges_map, object_height);
+
+    std::vector<coordf_t> boundaries;
+    boundaries.reserve(2 + base_ranges.size() * 2 + mixed_ranges.size() * 2);
+    boundaries.emplace_back(0.f);
+    boundaries.emplace_back(object_height);
+    for (const LayerHeightRangeOverride &range : base_ranges) {
+        boundaries.emplace_back(range.lo);
+        boundaries.emplace_back(range.hi);
+    }
+    for (const t_layer_height_range &range : mixed_ranges) {
+        boundaries.emplace_back(range.first);
+        boundaries.emplace_back(range.second);
+    }
+
+    std::sort(boundaries.begin(), boundaries.end());
+    boundaries.erase(std::unique(boundaries.begin(), boundaries.end(), [](coordf_t a, coordf_t b) {
+                        return std::abs(a - b) <= EPSILON;
+                    }),
+                     boundaries.end());
+
+    std::vector<LayerHeightRangeOverride> merged_ranges;
+    merged_ranges.reserve(boundaries.size());
+    for (size_t i = 1; i < boundaries.size(); ++i) {
+        const coordf_t lo = boundaries[i - 1];
+        const coordf_t hi = boundaries[i];
+        if (hi <= lo + EPSILON)
+            continue;
+
+        const coordf_t z_mid = 0.5f * (lo + hi);
+
+        coordf_t target_height = default_layer_height;
+        coordf_t base_height   = 0.f;
+        if (contains_z(mixed_ranges, z_mid)) {
+            target_height = dithering_step;
+        } else if (get_override_height(base_ranges, z_mid, base_height)) {
+            target_height = base_height;
+        }
+
+        if (std::abs(target_height - default_layer_height) <= EPSILON)
+            continue;
+
+        if (!merged_ranges.empty() &&
+            std::abs(merged_ranges.back().height - target_height) <= EPSILON &&
+            std::abs(merged_ranges.back().hi - lo) <= EPSILON) {
+            merged_ranges.back().hi = hi;
+        } else {
+            merged_ranges.push_back({ lo, hi, target_height });
+        }
+    }
+
+    t_layer_config_ranges out;
+    for (const LayerHeightRangeOverride &range : merged_ranges) {
+        if (range.hi <= range.lo + EPSILON)
+            continue;
+        ModelConfig cfg;
+        cfg.set_key_value("layer_height", new ConfigOptionFloat(range.height));
+        out.emplace(t_layer_height_range(range.lo, range.hi), std::move(cfg));
+    }
+    return out;
+}
+
+static bool mixed_state_heights(const MixedFilamentManager &mixed_mgr,
+                                size_t                     num_physical,
+                                size_t                     state_id,
+                                coordf_t                   lower_bound,
+                                coordf_t                   upper_bound,
+                                coordf_t                  &height_a,
+                                coordf_t                  &height_b)
+{
+    if (state_id <= num_physical)
+        return false;
+
+    const size_t idx = state_id - num_physical - 1;
+    const auto  &mixed = mixed_mgr.mixed_filaments();
+    if (idx >= mixed.size())
+        return false;
+
+    const int mix_b = std::clamp(mixed[idx].mix_b_percent, 0, 100);
+    const coordf_t pct_b = coordf_t(mix_b) / coordf_t(100.f);
+    const coordf_t pct_a = coordf_t(1.f) - pct_b;
+    const coordf_t lo = std::max<coordf_t>(0.01f, lower_bound);
+    const coordf_t hi = std::max<coordf_t>(lo, upper_bound);
+
+    height_a = std::max<coordf_t>(0.01f, lo + pct_a * (hi - lo));
+    height_b = std::max<coordf_t>(0.01f, lo + pct_b * (hi - lo));
+    return true;
+}
+
+static coordf_t mixed_state_height_at_z(const MixedStateCadence &state, coordf_t z)
+{
+    const coordf_t cycle = std::max<coordf_t>(0.01f, state.height_a + state.height_b);
+    coordf_t phase = std::fmod(std::max<coordf_t>(0.f, z), cycle);
+    if (phase < 0.f)
+        phase += cycle;
+    return (phase < state.height_a) ? state.height_a : state.height_b;
+}
+
+static void append_state_cadence_boundaries(std::vector<coordf_t> &boundaries,
+                                            const t_layer_height_range &range,
+                                            coordf_t                   height_a,
+                                            coordf_t                   height_b)
+{
+    const coordf_t cycle = height_a + height_b;
+    if (cycle <= EPSILON || range.second <= range.first + EPSILON)
+        return;
+
+    const int k_start = int(std::floor(range.first / cycle)) - 1;
+    coordf_t boundary = coordf_t(k_start) * cycle;
+    size_t guard = 0;
+    while (boundary <= range.second + cycle + EPSILON && guard++ < 200000) {
+        if (boundary > range.first + EPSILON && boundary < range.second - EPSILON)
+            boundaries.emplace_back(boundary);
+        const coordf_t split = boundary + height_a;
+        if (split > range.first + EPSILON && split < range.second - EPSILON)
+            boundaries.emplace_back(split);
+        boundary += cycle;
+    }
+}
+
+static t_layer_config_ranges layer_ranges_with_height_weighted_mixed(
+    const t_layer_config_ranges &base_ranges_map,
+    coordf_t                     object_height,
+    coordf_t                     default_layer_height,
+    const std::vector<MixedStateZRanges> &mixed_state_ranges,
+    const MixedFilamentManager  &mixed_mgr,
+    size_t                       num_physical,
+    coordf_t                     lower_bound,
+    coordf_t                     upper_bound)
+{
+    if (object_height <= EPSILON || mixed_state_ranges.empty())
+        return base_ranges_map;
+
+    const std::vector<LayerHeightRangeOverride> base_ranges = base_layer_height_overrides(base_ranges_map, object_height);
+
+    std::vector<MixedStateCadence> states;
+    states.reserve(mixed_state_ranges.size());
+    for (const MixedStateZRanges &state_ranges : mixed_state_ranges) {
+        coordf_t height_a = 0.f;
+        coordf_t height_b = 0.f;
+        if (!mixed_state_heights(mixed_mgr, num_physical, state_ranges.state_id, lower_bound, upper_bound, height_a, height_b))
+            continue;
+        states.push_back({ state_ranges.state_id, height_a, height_b, state_ranges.ranges });
+    }
+    if (states.empty())
+        return base_ranges_map;
+
+    std::vector<coordf_t> boundaries;
+    boundaries.reserve(2 + base_ranges.size() * 2 + states.size() * 64);
+    boundaries.emplace_back(0.f);
+    boundaries.emplace_back(object_height);
+    for (const LayerHeightRangeOverride &range : base_ranges) {
+        boundaries.emplace_back(range.lo);
+        boundaries.emplace_back(range.hi);
+    }
+    for (const MixedStateCadence &state : states) {
+        for (const t_layer_height_range &range : state.ranges) {
+            boundaries.emplace_back(range.first);
+            boundaries.emplace_back(range.second);
+            append_state_cadence_boundaries(boundaries, range, state.height_a, state.height_b);
+        }
+    }
+
+    std::sort(boundaries.begin(), boundaries.end());
+    boundaries.erase(std::unique(boundaries.begin(), boundaries.end(), [](coordf_t a, coordf_t b) {
+                        return std::abs(a - b) <= EPSILON;
+                    }),
+                     boundaries.end());
+
+    std::vector<LayerHeightRangeOverride> merged_ranges;
+    merged_ranges.reserve(boundaries.size());
+    for (size_t i = 1; i < boundaries.size(); ++i) {
+        const coordf_t lo = boundaries[i - 1];
+        const coordf_t hi = boundaries[i];
+        if (hi <= lo + EPSILON)
+            continue;
+
+        const coordf_t z_mid = 0.5f * (lo + hi);
+        coordf_t target_height = default_layer_height;
+        coordf_t base_height   = 0.f;
+        const bool has_base_override = get_override_height(base_ranges, z_mid, base_height);
+        if (has_base_override)
+            target_height = base_height;
+
+        bool has_mixed = false;
+        coordf_t mixed_height = target_height;
+        for (const MixedStateCadence &state : states) {
+            if (!contains_z(state.ranges, z_mid))
+                continue;
+            const coordf_t state_height = mixed_state_height_at_z(state, z_mid);
+            if (!has_mixed) {
+                mixed_height = state_height;
+                has_mixed = true;
+            } else {
+                mixed_height = std::min(mixed_height, state_height);
+            }
+        }
+        if (has_mixed)
+            target_height = mixed_height;
+
+        if (std::abs(target_height - default_layer_height) <= EPSILON)
+            continue;
+
+        if (!merged_ranges.empty() &&
+            std::abs(merged_ranges.back().height - target_height) <= EPSILON &&
+            std::abs(merged_ranges.back().hi - lo) <= EPSILON) {
+            merged_ranges.back().hi = hi;
+        } else {
+            merged_ranges.push_back({ lo, hi, target_height });
+        }
+    }
+
+    t_layer_config_ranges out;
+    for (const LayerHeightRangeOverride &range : merged_ranges) {
+        if (range.hi <= range.lo + EPSILON)
+            continue;
+        ModelConfig cfg;
+        cfg.set_key_value("layer_height", new ConfigOptionFloat(range.height));
+        out.emplace(t_layer_height_range(range.lo, range.hi), std::move(cfg));
+    }
+    return out;
+}
+
+} // namespace
+
+bool PrintObject::update_layer_height_profile(const ModelObject          &model_object,
+                                              const SlicingParameters    &slicing_parameters,
+                                              std::vector<coordf_t>      &layer_height_profile,
+                                              const PrintObject          *print_object)
 {
     bool updated = false;
 
+    const t_layer_config_ranges *ranges_to_use = &model_object.layer_config_ranges;
+    t_layer_config_ranges        mixed_gradient_ranges;
+    t_layer_config_ranges        dithering_ranges;
+    if (print_object != nullptr && print_object->print() != nullptr) {
+        const DynamicPrintConfig &full_cfg = print_object->print()->full_print_config();
+        const PrintConfig        &print_cfg = print_object->print()->config();
+
+        bool height_weighted_mode = print_cfg.mixed_filament_gradient_mode.value;
+        if (full_cfg.has("mixed_filament_gradient_mode")) {
+            if (const ConfigOptionBool *opt = full_cfg.option<ConfigOptionBool>("mixed_filament_gradient_mode"))
+                height_weighted_mode = opt->value;
+            else if (const ConfigOptionInt *opt = full_cfg.option<ConfigOptionInt>("mixed_filament_gradient_mode"))
+                height_weighted_mode = (opt->value != 0);
+        }
+
+        coordf_t mixed_lower = coordf_t(print_cfg.mixed_filament_height_lower_bound.value);
+        coordf_t mixed_upper = coordf_t(print_cfg.mixed_filament_height_upper_bound.value);
+        if (full_cfg.has("mixed_filament_height_lower_bound"))
+            mixed_lower = coordf_t(full_cfg.opt_float("mixed_filament_height_lower_bound"));
+        if (full_cfg.has("mixed_filament_height_upper_bound"))
+            mixed_upper = coordf_t(full_cfg.opt_float("mixed_filament_height_upper_bound"));
+        mixed_lower = std::max<coordf_t>(0.01f, mixed_lower);
+        mixed_upper = std::max<coordf_t>(mixed_lower, mixed_upper);
+
+        if (height_weighted_mode) {
+            const coordf_t object_height = slicing_parameters.object_print_z_uncompensated_height();
+            const auto mixed_states = collect_mixed_painted_z_ranges_by_state(*print_object, object_height);
+            if (!mixed_states.empty()) {
+                mixed_gradient_ranges = layer_ranges_with_height_weighted_mixed(*ranges_to_use,
+                                                                                object_height,
+                                                                                slicing_parameters.layer_height,
+                                                                                mixed_states,
+                                                                                print_object->print()->mixed_filament_manager(),
+                                                                                print_cfg.filament_colour.size(),
+                                                                                mixed_lower,
+                                                                                mixed_upper);
+                ranges_to_use = &mixed_gradient_ranges;
+            }
+        }
+
+        coordf_t                  dithering_step = coordf_t(print_object->print()->config().dithering_z_step_size.value);
+        bool                      local_z_mode = print_object->print()->config().dithering_local_z_mode.value;
+        bool                      painted_zones_only = print_object->print()->config().dithering_step_painted_zones_only.value;
+        if (full_cfg.has("dithering_z_step_size"))
+            dithering_step = coordf_t(full_cfg.opt_float("dithering_z_step_size"));
+        if (full_cfg.has("dithering_local_z_mode")) {
+            if (const ConfigOptionBool *opt = full_cfg.option<ConfigOptionBool>("dithering_local_z_mode"))
+                local_z_mode = opt->value;
+            else if (const ConfigOptionInt *opt = full_cfg.option<ConfigOptionInt>("dithering_local_z_mode"))
+                local_z_mode = (opt->value != 0);
+        }
+        if (full_cfg.has("dithering_step_painted_zones_only"))
+            painted_zones_only = full_cfg.opt_bool("dithering_step_painted_zones_only");
+
+        if (!height_weighted_mode && !local_z_mode && dithering_step > EPSILON) {
+            const coordf_t object_height = slicing_parameters.object_print_z_uncompensated_height();
+            std::vector<t_layer_height_range> mixed_ranges;
+            if (painted_zones_only)
+                mixed_ranges = collect_mixed_painted_z_ranges(*print_object, object_height);
+            else if (object_height > EPSILON)
+                mixed_ranges.emplace_back(0.f, object_height);
+
+            if (!mixed_ranges.empty()) {
+                dithering_ranges = layer_ranges_with_dithering(*ranges_to_use,
+                                                               object_height,
+                                                               slicing_parameters.layer_height,
+                                                               mixed_ranges,
+                                                               dithering_step);
+                ranges_to_use = &dithering_ranges;
+            }
+        }
+    }
+    const bool has_dithering_ranges = (ranges_to_use != &model_object.layer_config_ranges);
+
     if (layer_height_profile.empty()) {
         // use the constructor because the assignement is crashing on ASAN OsX
         layer_height_profile = std::vector<coordf_t>(model_object.layer_height_profile.get());
-//        layer_height_profile = model_object.layer_height_profile;
-        // The layer height returned is sampled with high density for the UI layer height painting
-        // and smoothing tool to work.
         updated = true;
     }
 
@@ -3741,10 +4306,8 @@ bool PrintObject::update_layer_height_profile(const ModelObject &model_object, c
             std::abs(layer_height_profile[layer_height_profile.size() - 2] - slicing_parameters.object_print_z_uncompensated_max + slicing_parameters.object_print_z_min) > 1e-3))
         layer_height_profile.clear();
 
-    if (layer_height_profile.empty() || layer_height_profile[1] != slicing_parameters.first_object_layer_height) {
-        //layer_height_profile = layer_height_profile_adaptive(slicing_parameters, model_object.layer_config_ranges, model_object.volumes);
-        layer_height_profile = layer_height_profile_from_ranges(slicing_parameters, model_object.layer_config_ranges);
-        // The layer height profile is already compressed.
+    if (layer_height_profile.empty() || layer_height_profile[1] != slicing_parameters.first_object_layer_height || has_dithering_ranges) {
+        layer_height_profile = layer_height_profile_from_ranges(slicing_parameters, *ranges_to_use);
         updated = true;
     }
 

src/libslic3r/TriangleSelector.cpp

@@ -1691,9 +1691,11 @@ void TriangleSelector::get_seed_fill_contour_recursive(const int facet_idx, cons
 
 TriangleSelector::TriangleSplittingData TriangleSelector::serialize() const {
     // Each original triangle of the mesh is assigned a number encoding its state
-    // or how it is split. Each triangle is encoded by 4 bits (xxyy) or 8 bits (zzzzxxyy):
+    // or how it is split. Each triangle is encoded by 4 bits (xxyy), 8 bits
+    // (zzzzxxyy), or 12 bits (wwwwzzzzxxyy):
     // leaf triangle: xx = EnforcerBlockerType (Only values 0, 1, and 2. Value 3 is used as an indicator for additional 4 bits.), yy = 0
-    // leaf triangle: xx = 0b11, yy = 0b00, zzzz = EnforcerBlockerType (subtracted by 3)
+    // leaf triangle: xx = 0b11, yy = 0b00, zzzz = EnforcerBlockerType (subtracted by 3) for states 3..16
+    // leaf triangle: xx = 0b11, yy = 0b00, zzzz = 0b1110, wwww = EnforcerBlockerType (subtracted by 17) for states 17..32
     // non-leaf:      xx = special side, yy = number of split sides
     // These are bitwise appended and formed into one 64-bit integer.
 
@@ -1736,13 +1738,25 @@ TriangleSelector::TriangleSplittingData TriangleSelector::serialize() const {
                     data.used_states[n] = true;
 
                 if (n >= 3) {
-                    assert(n <= 16);
-                    if (n <= 16) {
-                        // Store "11" plus 4 bits of (n-3).
-                        data.bitstream.insert(data.bitstream.end(), { true, true });
-                        n -= 3;
+                    assert(n <= int(EnforcerBlockerType::ExtruderMax));
+
+                    auto push_nibble = [&data = this->data](int value) {
                         for (size_t bit_idx = 0; bit_idx < 4; ++bit_idx)
-                            data.bitstream.push_back(n & (uint64_t(0b0001) << bit_idx));
+                            data.bitstream.push_back((value & (1 << int(bit_idx))) != 0);
+                    };
+
+                    // Store "11" plus either one nibble (legacy 3..16) or
+                    // an escaped second nibble for 17..32.
+                    data.bitstream.insert(data.bitstream.end(), { true, true });
+                    if (n <= 16) {
+                        push_nibble(n - 3);
+                    } else {
+                        // 0b1110 marks the extended range 17..32.
+                        constexpr int extended_prefix = 0b1110;
+                        const int encoded = n - 17;
+                        assert(encoded >= 0 && encoded <= 15);
+                        push_nibble(extended_prefix);
+                        push_nibble(encoded);
                     }
                 } else {
                     // Simple case, compatible with PrusaSlicer 2.3.1 and older for storing paint on supports and seams.
@@ -1818,8 +1832,19 @@ void TriangleSelector::deserialize(const TriangleSplittingData &data,
             int num_of_split_sides = code & 0b11;
             int num_of_children = num_of_split_sides == 0 ? 0 : num_of_split_sides + 1;
             bool is_split = num_of_children != 0;
-            // Only valid if not is_split. Value of the second nibble was subtracted by 3, so it is added back.
-            auto state = is_split ? EnforcerBlockerType::NONE : EnforcerBlockerType((code & 0b1100) == 0b1100 ? next_nibble() + 3 : code >> 2);
+            // Only valid if not is_split.
+            auto decode_leaf_state = [&next_nibble](int leaf_code) -> EnforcerBlockerType {
+                if ((leaf_code & 0b1100) != 0b1100)
+                    return EnforcerBlockerType(leaf_code >> 2);
+
+                const int extended = next_nibble();
+                if (extended == 0b1110)
+                    return EnforcerBlockerType(next_nibble() + 17);
+
+                // Legacy path (states 3..16, plus historical fallback for 18).
+                return EnforcerBlockerType(extended + 3);
+            };
+            auto state = is_split ? EnforcerBlockerType::NONE : decode_leaf_state(code);
 
             // BBS
             if (state == to_delete_filament)
@@ -1916,7 +1941,17 @@ void TriangleSelector::TriangleSplittingData::update_used_states(const size_t bi
         if (const bool is_split = (code & 0b11) != 0; is_split)
             continue;
 
-        const uint8_t facet_state = (code & 0b1100) == 0b1100 ? read_next_nibble() + 3 : code >> 2;
+        uint8_t facet_state = 0;
+        if ((code & 0b1100) != 0b1100) {
+            facet_state = code >> 2;
+        } else {
+            const uint8_t extended = read_next_nibble();
+            if (extended == 0b1110)
+                facet_state = read_next_nibble() + 17;
+            else
+                facet_state = extended + 3;
+        }
+
         assert(facet_state < this->used_states.size());
         if (facet_state >= this->used_states.size())
             continue;
@@ -1946,9 +1981,17 @@ bool TriangleSelector::has_facets(const TriangleSplittingData &data, const Enfor
         auto num_children_or_state = [&next_nibble]() -> int {
             int code               = next_nibble();
             int num_of_split_sides = code & 0b11;
-            return num_of_split_sides == 0 ?
-                ((code & 0b1100) == 0b1100 ? next_nibble() + 3 : code >> 2) :
-                - num_of_split_sides - 1;
+            if (num_of_split_sides != 0)
+                return - num_of_split_sides - 1;
+
+            if ((code & 0b1100) != 0b1100)
+                return code >> 2;
+
+            const int extended = next_nibble();
+            if (extended == 0b1110)
+                return next_nibble() + 17;
+
+            return extended + 3;
         };
 
         int state = num_children_or_state();
@@ -2524,4 +2567,17 @@ TriangleSelector::TriangleSplittingData TriangleSelector::remap_painting(
     return target_selector.serialize();
 }
 
+void TriangleSelector::shift_states_above(EnforcerBlockerType threshold, int delta)
+{
+    for (Triangle &triangle : m_triangles) {
+        if (triangle.is_split() || !triangle.valid()) continue;
+        EnforcerBlockerType s = triangle.get_state();
+        if (s != EnforcerBlockerType::NONE && s >= threshold) {
+            int new_val = static_cast<int>(s) + delta;
+            if (new_val >= 0)
+                triangle.set_state(EnforcerBlockerType(new_val));
+        }
+    }
+}
+
 } // namespace Slic3r

src/libslic3r/TriangleSelector.hpp

@@ -17,7 +17,8 @@ enum class EnforcerBlockerType : int8_t {
     BLOCKER   = 2,
     // For the fuzzy skin, we use just two values (NONE and FUZZY_SKIN).
     FUZZY_SKIN = ENFORCER,
-    // Maximum is 15. The value is serialized in TriangleSelector into 6 bits using a 2 bit prefix code.
+    // Extruder states use compact nibble encoding with extended fallback in TriangleSelector serialization.
+    // Values above 16 are supported as long as they fit in EnforcerBlockerType (int8_t).
     Extruder1 = ENFORCER,
     Extruder2 = BLOCKER,
     Extruder3,
@@ -34,7 +35,23 @@ enum class EnforcerBlockerType : int8_t {
     Extruder14,
     Extruder15,
     Extruder16,
-    ExtruderMax = Extruder16
+    Extruder17,
+    Extruder18,
+    Extruder19,
+    Extruder20,
+    Extruder21,
+    Extruder22,
+    Extruder23,
+    Extruder24,
+    Extruder25,
+    Extruder26,
+    Extruder27,
+    Extruder28,
+    Extruder29,
+    Extruder30,
+    Extruder31,
+    Extruder32,
+    ExtruderMax = Extruder32
 };
 
 // Type alias for the state mapping array to improve code readability
@@ -391,6 +408,9 @@ public:
         const indexed_triangle_set& target_its,
         const Transform3d& target_transform,
         const std::optional<std::reference_wrapper<const TriangleSplittingData>>& existing_painting);
+    // Shift all non-NONE leaf triangle states >= threshold by delta.
+    // Used to renumber painted filament IDs after a filament slot is inserted or removed.
+    void shift_states_above(EnforcerBlockerType threshold, int delta);
 
 protected:
     // Triangle and info about how it's split.

src/libslic3r/filament_mixer.cpp

@@ -0,0 +1,81 @@
+#include "filament_mixer.h"
+
+#include <algorithm>
+#include <cmath>
+
+#include "filament_mixer_model.h"
+
+namespace Slic3r {
+namespace {
+
+inline float clamp01(float x)
+{
+    return std::max(0.0f, std::min(1.0f, x));
+}
+
+inline float srgb_to_linear(float x)
+{
+    return (x >= 0.04045f) ? std::pow((x + 0.055f) / 1.055f, 2.4f) : x / 12.92f;
+}
+
+inline float linear_to_srgb(float x)
+{
+    return (x >= 0.0031308f) ? (1.055f * std::pow(x, 1.0f / 2.4f) - 0.055f) : (12.92f * x);
+}
+
+inline unsigned char to_u8(float x)
+{
+    const float clamped = clamp01(x);
+    return static_cast<unsigned char>(clamped * 255.0f + 0.5f);
+}
+
+inline float to_f01(unsigned char x)
+{
+    return static_cast<float>(x) / 255.0f;
+}
+
+} // namespace
+
+void filament_mixer_lerp(unsigned char r1, unsigned char g1, unsigned char b1,
+                         unsigned char r2, unsigned char g2, unsigned char b2,
+                         float t,
+                         unsigned char* out_r, unsigned char* out_g, unsigned char* out_b)
+{
+    ::filament_mixer::lerp(r1, g1, b1, r2, g2, b2, t, out_r, out_g, out_b);
+}
+
+void filament_mixer_lerp_float(float r1, float g1, float b1,
+                               float r2, float g2, float b2,
+                               float t,
+                               float* out_r, float* out_g, float* out_b)
+{
+    unsigned char ur = 0, ug = 0, ub = 0;
+    filament_mixer_lerp(to_u8(r1), to_u8(g1), to_u8(b1),
+                        to_u8(r2), to_u8(g2), to_u8(b2),
+                        t, &ur, &ug, &ub);
+    *out_r = to_f01(ur);
+    *out_g = to_f01(ug);
+    *out_b = to_f01(ub);
+}
+
+void filament_mixer_lerp_linear_float(float r1, float g1, float b1,
+                                      float r2, float g2, float b2,
+                                      float t,
+                                      float* out_r, float* out_g, float* out_b)
+{
+    const float sr1 = linear_to_srgb(clamp01(r1));
+    const float sg1 = linear_to_srgb(clamp01(g1));
+    const float sb1 = linear_to_srgb(clamp01(b1));
+    const float sr2 = linear_to_srgb(clamp01(r2));
+    const float sg2 = linear_to_srgb(clamp01(g2));
+    const float sb2 = linear_to_srgb(clamp01(b2));
+
+    float out_sr = 0.0f, out_sg = 0.0f, out_sb = 0.0f;
+    filament_mixer_lerp_float(sr1, sg1, sb1, sr2, sg2, sb2, t, &out_sr, &out_sg, &out_sb);
+
+    *out_r = srgb_to_linear(clamp01(out_sr));
+    *out_g = srgb_to_linear(clamp01(out_sg));
+    *out_b = srgb_to_linear(clamp01(out_sb));
+}
+
+} // namespace Slic3r

src/libslic3r/filament_mixer.h

@@ -0,0 +1,23 @@
+#ifndef SLIC3R_FILAMENT_MIXER_H
+#define SLIC3R_FILAMENT_MIXER_H
+
+namespace Slic3r {
+
+void filament_mixer_lerp(unsigned char r1, unsigned char g1, unsigned char b1,
+                         unsigned char r2, unsigned char g2, unsigned char b2,
+                         float t,
+                         unsigned char* out_r, unsigned char* out_g, unsigned char* out_b);
+
+void filament_mixer_lerp_float(float r1, float g1, float b1,
+                               float r2, float g2, float b2,
+                               float t,
+                               float* out_r, float* out_g, float* out_b);
+
+void filament_mixer_lerp_linear_float(float r1, float g1, float b1,
+                                      float r2, float g2, float b2,
+                                      float t,
+                                      float* out_r, float* out_g, float* out_b);
+
+} // namespace Slic3r
+
+#endif

src/libslic3r/filament_mixer_model.h

@@ -0,0 +1,819 @@
+/*
+ * FilamentMixer — Header-only C++ pigment color mixer
+ *
+ * Filament mixer implementation using a degree-4 polynomial regression
+ * trained to approximate Mixbox behavior (Mean Delta-E ~2.07).
+ * This library does not include Mixbox source code, binaries, or data files.
+ *
+ * Usage:
+ *   #include "filament_mixer_model.h"
+ *
+ *   unsigned char r, g, b;
+ *   filament_mixer::lerp(0, 33, 133,  252, 211, 0,  0.5f, &r, &g, &b);
+ *   // r=47, g=141, b=56  (blue + yellow → green)
+ *
+ * No dependencies beyond the C++ standard library.
+ *
+ * MIT License
+ *
+ * Copyright (c) 2026 Justin Hayes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef FILAMENT_MIXER_H
+#define FILAMENT_MIXER_H
+
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+
+namespace filament_mixer {
+namespace detail {
+
+// BEGIN AUTO-GENERATED COEFFICIENTS
+// Auto-generated by scripts/export_poly_coefficients.py
+// Do not edit manually.
+// Degree-4 polynomial, 330 features, 7 inputs
+
+static const int POLY_DEGREE = 4;
+static const int N_FEATURES = 330;
+static const int N_INPUTS = 7;
+
+static const int POWERS[330][7] = {
+    {0, 0, 0, 0, 0, 0, 0},
+    {1, 0, 0, 0, 0, 0, 0},
+    {0, 1, 0, 0, 0, 0, 0},
+    {0, 0, 1, 0, 0, 0, 0},
+    {0, 0, 0, 1, 0, 0, 0},
+    {0, 0, 0, 0, 1, 0, 0},
+    {0, 0, 0, 0, 0, 1, 0},
+    {0, 0, 0, 0, 0, 0, 1},
+    {2, 0, 0, 0, 0, 0, 0},
+    {1, 1, 0, 0, 0, 0, 0},
+    {1, 0, 1, 0, 0, 0, 0},
+    {1, 0, 0, 1, 0, 0, 0},
+    {1, 0, 0, 0, 1, 0, 0},
+    {1, 0, 0, 0, 0, 1, 0},
+    {1, 0, 0, 0, 0, 0, 1},
+    {0, 2, 0, 0, 0, 0, 0},
+    {0, 1, 1, 0, 0, 0, 0},
+    {0, 1, 0, 1, 0, 0, 0},
+    {0, 1, 0, 0, 1, 0, 0},
+    {0, 1, 0, 0, 0, 1, 0},
+    {0, 1, 0, 0, 0, 0, 1},
+    {0, 0, 2, 0, 0, 0, 0},
+    {0, 0, 1, 1, 0, 0, 0},
+    {0, 0, 1, 0, 1, 0, 0},
+    {0, 0, 1, 0, 0, 1, 0},
+    {0, 0, 1, 0, 0, 0, 1},
+    {0, 0, 0, 2, 0, 0, 0},
+    {0, 0, 0, 1, 1, 0, 0},
+    {0, 0, 0, 1, 0, 1, 0},
+    {0, 0, 0, 1, 0, 0, 1},
+    {0, 0, 0, 0, 2, 0, 0},
+    {0, 0, 0, 0, 1, 1, 0},
+    {0, 0, 0, 0, 1, 0, 1},
+    {0, 0, 0, 0, 0, 2, 0},
+    {0, 0, 0, 0, 0, 1, 1},
+    {0, 0, 0, 0, 0, 0, 2},
+    {3, 0, 0, 0, 0, 0, 0},
+    {2, 1, 0, 0, 0, 0, 0},
+    {2, 0, 1, 0, 0, 0, 0},
+    {2, 0, 0, 1, 0, 0, 0},
+    {2, 0, 0, 0, 1, 0, 0},
+    {2, 0, 0, 0, 0, 1, 0},
+    {2, 0, 0, 0, 0, 0, 1},
+    {1, 2, 0, 0, 0, 0, 0},
+    {1, 1, 1, 0, 0, 0, 0},
+    {1, 1, 0, 1, 0, 0, 0},
+    {1, 1, 0, 0, 1, 0, 0},
+    {1, 1, 0, 0, 0, 1, 0},
+    {1, 1, 0, 0, 0, 0, 1},
+    {1, 0, 2, 0, 0, 0, 0},
+    {1, 0, 1, 1, 0, 0, 0},
+    {1, 0, 1, 0, 1, 0, 0},
+    {1, 0, 1, 0, 0, 1, 0},
+    {1, 0, 1, 0, 0, 0, 1},
+    {1, 0, 0, 2, 0, 0, 0},
+    {1, 0, 0, 1, 1, 0, 0},
+    {1, 0, 0, 1, 0, 1, 0},
+    {1, 0, 0, 1, 0, 0, 1},
+    {1, 0, 0, 0, 2, 0, 0},
+    {1, 0, 0, 0, 1, 1, 0},
+    {1, 0, 0, 0, 1, 0, 1},
+    {1, 0, 0, 0, 0, 2, 0},
+    {1, 0, 0, 0, 0, 1, 1},
+    {1, 0, 0, 0, 0, 0, 2},
+    {0, 3, 0, 0, 0, 0, 0},
+    {0, 2, 1, 0, 0, 0, 0},
+    {0, 2, 0, 1, 0, 0, 0},
+    {0, 2, 0, 0, 1, 0, 0},
+    {0, 2, 0, 0, 0, 1, 0},
+    {0, 2, 0, 0, 0, 0, 1},
+    {0, 1, 2, 0, 0, 0, 0},
+    {0, 1, 1, 1, 0, 0, 0},
+    {0, 1, 1, 0, 1, 0, 0},
+    {0, 1, 1, 0, 0, 1, 0},
+    {0, 1, 1, 0, 0, 0, 1},
+    {0, 1, 0, 2, 0, 0, 0},
+    {0, 1, 0, 1, 1, 0, 0},
+    {0, 1, 0, 1, 0, 1, 0},
+    {0, 1, 0, 1, 0, 0, 1},
+    {0, 1, 0, 0, 2, 0, 0},
+    {0, 1, 0, 0, 1, 1, 0},
+    {0, 1, 0, 0, 1, 0, 1},
+    {0, 1, 0, 0, 0, 2, 0},
+    {0, 1, 0, 0, 0, 1, 1},
+    {0, 1, 0, 0, 0, 0, 2},
+    {0, 0, 3, 0, 0, 0, 0},
+    {0, 0, 2, 1, 0, 0, 0},
+    {0, 0, 2, 0, 1, 0, 0},
+    {0, 0, 2, 0, 0, 1, 0},
+    {0, 0, 2, 0, 0, 0, 1},
+    {0, 0, 1, 2, 0, 0, 0},
+    {0, 0, 1, 1, 1, 0, 0},
+    {0, 0, 1, 1, 0, 1, 0},
+    {0, 0, 1, 1, 0, 0, 1},
+    {0, 0, 1, 0, 2, 0, 0},
+    {0, 0, 1, 0, 1, 1, 0},
+    {0, 0, 1, 0, 1, 0, 1},
+    {0, 0, 1, 0, 0, 2, 0},
+    {0, 0, 1, 0, 0, 1, 1},
+    {0, 0, 1, 0, 0, 0, 2},
+    {0, 0, 0, 3, 0, 0, 0},
+    {0, 0, 0, 2, 1, 0, 0},
+    {0, 0, 0, 2, 0, 1, 0},
+    {0, 0, 0, 2, 0, 0, 1},
+    {0, 0, 0, 1, 2, 0, 0},
+    {0, 0, 0, 1, 1, 1, 0},
+    {0, 0, 0, 1, 1, 0, 1},
+    {0, 0, 0, 1, 0, 2, 0},
+    {0, 0, 0, 1, 0, 1, 1},
+    {0, 0, 0, 1, 0, 0, 2},
+    {0, 0, 0, 0, 3, 0, 0},
+    {0, 0, 0, 0, 2, 1, 0},
+    {0, 0, 0, 0, 2, 0, 1},
+    {0, 0, 0, 0, 1, 2, 0},
+    {0, 0, 0, 0, 1, 1, 1},
+    {0, 0, 0, 0, 1, 0, 2},
+    {0, 0, 0, 0, 0, 3, 0},
+    {0, 0, 0, 0, 0, 2, 1},
+    {0, 0, 0, 0, 0, 1, 2},
+    {0, 0, 0, 0, 0, 0, 3},
+    {4, 0, 0, 0, 0, 0, 0},
+    {3, 1, 0, 0, 0, 0, 0},
+    {3, 0, 1, 0, 0, 0, 0},
+    {3, 0, 0, 1, 0, 0, 0},
+    {3, 0, 0, 0, 1, 0, 0},
+    {3, 0, 0, 0, 0, 1, 0},
+    {3, 0, 0, 0, 0, 0, 1},
+    {2, 2, 0, 0, 0, 0, 0},
+    {2, 1, 1, 0, 0, 0, 0},
+    {2, 1, 0, 1, 0, 0, 0},
+    {2, 1, 0, 0, 1, 0, 0},
+    {2, 1, 0, 0, 0, 1, 0},
+    {2, 1, 0, 0, 0, 0, 1},
+    {2, 0, 2, 0, 0, 0, 0},
+    {2, 0, 1, 1, 0, 0, 0},
+    {2, 0, 1, 0, 1, 0, 0},
+    {2, 0, 1, 0, 0, 1, 0},
+    {2, 0, 1, 0, 0, 0, 1},
+    {2, 0, 0, 2, 0, 0, 0},
+    {2, 0, 0, 1, 1, 0, 0},
+    {2, 0, 0, 1, 0, 1, 0},
+    {2, 0, 0, 1, 0, 0, 1},
+    {2, 0, 0, 0, 2, 0, 0},
+    {2, 0, 0, 0, 1, 1, 0},
+    {2, 0, 0, 0, 1, 0, 1},
+    {2, 0, 0, 0, 0, 2, 0},
+    {2, 0, 0, 0, 0, 1, 1},
+    {2, 0, 0, 0, 0, 0, 2},
+    {1, 3, 0, 0, 0, 0, 0},
+    {1, 2, 1, 0, 0, 0, 0},
+    {1, 2, 0, 1, 0, 0, 0},
+    {1, 2, 0, 0, 1, 0, 0},
+    {1, 2, 0, 0, 0, 1, 0},
+    {1, 2, 0, 0, 0, 0, 1},
+    {1, 1, 2, 0, 0, 0, 0},
+    {1, 1, 1, 1, 0, 0, 0},
+    {1, 1, 1, 0, 1, 0, 0},
+    {1, 1, 1, 0, 0, 1, 0},
+    {1, 1, 1, 0, 0, 0, 1},
+    {1, 1, 0, 2, 0, 0, 0},
+    {1, 1, 0, 1, 1, 0, 0},
+    {1, 1, 0, 1, 0, 1, 0},
+    {1, 1, 0, 1, 0, 0, 1},
+    {1, 1, 0, 0, 2, 0, 0},
+    {1, 1, 0, 0, 1, 1, 0},
+    {1, 1, 0, 0, 1, 0, 1},
+    {1, 1, 0, 0, 0, 2, 0},
+    {1, 1, 0, 0, 0, 1, 1},
+    {1, 1, 0, 0, 0, 0, 2},
+    {1, 0, 3, 0, 0, 0, 0},
+    {1, 0, 2, 1, 0, 0, 0},
+    {1, 0, 2, 0, 1, 0, 0},
+    {1, 0, 2, 0, 0, 1, 0},
+    {1, 0, 2, 0, 0, 0, 1},
+    {1, 0, 1, 2, 0, 0, 0},
+    {1, 0, 1, 1, 1, 0, 0},
+    {1, 0, 1, 1, 0, 1, 0},
+    {1, 0, 1, 1, 0, 0, 1},
+    {1, 0, 1, 0, 2, 0, 0},
+    {1, 0, 1, 0, 1, 1, 0},
+    {1, 0, 1, 0, 1, 0, 1},
+    {1, 0, 1, 0, 0, 2, 0},
+    {1, 0, 1, 0, 0, 1, 1},
+    {1, 0, 1, 0, 0, 0, 2},
+    {1, 0, 0, 3, 0, 0, 0},
+    {1, 0, 0, 2, 1, 0, 0},
+    {1, 0, 0, 2, 0, 1, 0},
+    {1, 0, 0, 2, 0, 0, 1},
+    {1, 0, 0, 1, 2, 0, 0},
+    {1, 0, 0, 1, 1, 1, 0},
+    {1, 0, 0, 1, 1, 0, 1},
+    {1, 0, 0, 1, 0, 2, 0},
+    {1, 0, 0, 1, 0, 1, 1},
+    {1, 0, 0, 1, 0, 0, 2},
+    {1, 0, 0, 0, 3, 0, 0},
+    {1, 0, 0, 0, 2, 1, 0},
+    {1, 0, 0, 0, 2, 0, 1},
+    {1, 0, 0, 0, 1, 2, 0},
+    {1, 0, 0, 0, 1, 1, 1},
+    {1, 0, 0, 0, 1, 0, 2},
+    {1, 0, 0, 0, 0, 3, 0},
+    {1, 0, 0, 0, 0, 2, 1},
+    {1, 0, 0, 0, 0, 1, 2},
+    {1, 0, 0, 0, 0, 0, 3},
+    {0, 4, 0, 0, 0, 0, 0},
+    {0, 3, 1, 0, 0, 0, 0},
+    {0, 3, 0, 1, 0, 0, 0},
+    {0, 3, 0, 0, 1, 0, 0},
+    {0, 3, 0, 0, 0, 1, 0},
+    {0, 3, 0, 0, 0, 0, 1},
+    {0, 2, 2, 0, 0, 0, 0},
+    {0, 2, 1, 1, 0, 0, 0},
+    {0, 2, 1, 0, 1, 0, 0},
+    {0, 2, 1, 0, 0, 1, 0},
+    {0, 2, 1, 0, 0, 0, 1},
+    {0, 2, 0, 2, 0, 0, 0},
+    {0, 2, 0, 1, 1, 0, 0},
+    {0, 2, 0, 1, 0, 1, 0},
+    {0, 2, 0, 1, 0, 0, 1},
+    {0, 2, 0, 0, 2, 0, 0},
+    {0, 2, 0, 0, 1, 1, 0},
+    {0, 2, 0, 0, 1, 0, 1},
+    {0, 2, 0, 0, 0, 2, 0},
+    {0, 2, 0, 0, 0, 1, 1},
+    {0, 2, 0, 0, 0, 0, 2},
+    {0, 1, 3, 0, 0, 0, 0},
+    {0, 1, 2, 1, 0, 0, 0},
+    {0, 1, 2, 0, 1, 0, 0},
+    {0, 1, 2, 0, 0, 1, 0},
+    {0, 1, 2, 0, 0, 0, 1},
+    {0, 1, 1, 2, 0, 0, 0},
+    {0, 1, 1, 1, 1, 0, 0},
+    {0, 1, 1, 1, 0, 1, 0},
+    {0, 1, 1, 1, 0, 0, 1},
+    {0, 1, 1, 0, 2, 0, 0},
+    {0, 1, 1, 0, 1, 1, 0},
+    {0, 1, 1, 0, 1, 0, 1},
+    {0, 1, 1, 0, 0, 2, 0},
+    {0, 1, 1, 0, 0, 1, 1},
+    {0, 1, 1, 0, 0, 0, 2},
+    {0, 1, 0, 3, 0, 0, 0},
+    {0, 1, 0, 2, 1, 0, 0},
+    {0, 1, 0, 2, 0, 1, 0},
+    {0, 1, 0, 2, 0, 0, 1},
+    {0, 1, 0, 1, 2, 0, 0},
+    {0, 1, 0, 1, 1, 1, 0},
+    {0, 1, 0, 1, 1, 0, 1},
+    {0, 1, 0, 1, 0, 2, 0},
+    {0, 1, 0, 1, 0, 1, 1},
+    {0, 1, 0, 1, 0, 0, 2},
+    {0, 1, 0, 0, 3, 0, 0},
+    {0, 1, 0, 0, 2, 1, 0},
+    {0, 1, 0, 0, 2, 0, 1},
+    {0, 1, 0, 0, 1, 2, 0},
+    {0, 1, 0, 0, 1, 1, 1},
+    {0, 1, 0, 0, 1, 0, 2},
+    {0, 1, 0, 0, 0, 3, 0},
+    {0, 1, 0, 0, 0, 2, 1},
+    {0, 1, 0, 0, 0, 1, 2},
+    {0, 1, 0, 0, 0, 0, 3},
+    {0, 0, 4, 0, 0, 0, 0},
+    {0, 0, 3, 1, 0, 0, 0},
+    {0, 0, 3, 0, 1, 0, 0},
+    {0, 0, 3, 0, 0, 1, 0},
+    {0, 0, 3, 0, 0, 0, 1},
+    {0, 0, 2, 2, 0, 0, 0},
+    {0, 0, 2, 1, 1, 0, 0},
+    {0, 0, 2, 1, 0, 1, 0},
+    {0, 0, 2, 1, 0, 0, 1},
+    {0, 0, 2, 0, 2, 0, 0},
+    {0, 0, 2, 0, 1, 1, 0},
+    {0, 0, 2, 0, 1, 0, 1},
+    {0, 0, 2, 0, 0, 2, 0},
+    {0, 0, 2, 0, 0, 1, 1},
+    {0, 0, 2, 0, 0, 0, 2},
+    {0, 0, 1, 3, 0, 0, 0},
+    {0, 0, 1, 2, 1, 0, 0},
+    {0, 0, 1, 2, 0, 1, 0},
+    {0, 0, 1, 2, 0, 0, 1},
+    {0, 0, 1, 1, 2, 0, 0},
+    {0, 0, 1, 1, 1, 1, 0},
+    {0, 0, 1, 1, 1, 0, 1},
+    {0, 0, 1, 1, 0, 2, 0},
+    {0, 0, 1, 1, 0, 1, 1},
+    {0, 0, 1, 1, 0, 0, 2},
+    {0, 0, 1, 0, 3, 0, 0},
+    {0, 0, 1, 0, 2, 1, 0},
+    {0, 0, 1, 0, 2, 0, 1},
+    {0, 0, 1, 0, 1, 2, 0},
+    {0, 0, 1, 0, 1, 1, 1},
+    {0, 0, 1, 0, 1, 0, 2},
+    {0, 0, 1, 0, 0, 3, 0},
+    {0, 0, 1, 0, 0, 2, 1},
+    {0, 0, 1, 0, 0, 1, 2},
+    {0, 0, 1, 0, 0, 0, 3},
+    {0, 0, 0, 4, 0, 0, 0},
+    {0, 0, 0, 3, 1, 0, 0},
+    {0, 0, 0, 3, 0, 1, 0},
+    {0, 0, 0, 3, 0, 0, 1},
+    {0, 0, 0, 2, 2, 0, 0},
+    {0, 0, 0, 2, 1, 1, 0},
+    {0, 0, 0, 2, 1, 0, 1},
+    {0, 0, 0, 2, 0, 2, 0},
+    {0, 0, 0, 2, 0, 1, 1},
+    {0, 0, 0, 2, 0, 0, 2},
+    {0, 0, 0, 1, 3, 0, 0},
+    {0, 0, 0, 1, 2, 1, 0},
+    {0, 0, 0, 1, 2, 0, 1},
+    {0, 0, 0, 1, 1, 2, 0},
+    {0, 0, 0, 1, 1, 1, 1},
+    {0, 0, 0, 1, 1, 0, 2},
+    {0, 0, 0, 1, 0, 3, 0},
+    {0, 0, 0, 1, 0, 2, 1},
+    {0, 0, 0, 1, 0, 1, 2},
+    {0, 0, 0, 1, 0, 0, 3},
+    {0, 0, 0, 0, 4, 0, 0},
+    {0, 0, 0, 0, 3, 1, 0},
+    {0, 0, 0, 0, 3, 0, 1},
+    {0, 0, 0, 0, 2, 2, 0},
+    {0, 0, 0, 0, 2, 1, 1},
+    {0, 0, 0, 0, 2, 0, 2},
+    {0, 0, 0, 0, 1, 3, 0},
+    {0, 0, 0, 0, 1, 2, 1},
+    {0, 0, 0, 0, 1, 1, 2},
+    {0, 0, 0, 0, 1, 0, 3},
+    {0, 0, 0, 0, 0, 4, 0},
+    {0, 0, 0, 0, 0, 3, 1},
+    {0, 0, 0, 0, 0, 2, 2},
+    {0, 0, 0, 0, 0, 1, 3},
+    {0, 0, 0, 0, 0, 0, 4}
+};
+
+static const double COEF[330][3] = {
+    {8.70954844857314666e-12, 1.27926950848359881e-09, -2.06865474316332923e-09},
+    {1.05783308354771544e+00, -8.02119209663359686e-03, -7.88705651445470723e-02},
+    {1.35905954452774837e-02, 8.71267975138422468e-01, 1.04898760410704936e-01},
+    {-4.16452026099768252e-02, 1.75465381596434100e-02, 1.00224594702931546e+00},
+    {4.50321316661211821e-02, -7.11409155427628892e-02, 3.91232300778902690e-03},
+    {1.76675507851922452e-02, -1.32709276116036640e-01, 6.36935270589509828e-02},
+    {-5.23434830565911030e-02, 3.77681739012521722e-02, -2.08691145087504179e-02},
+    {-2.33722556520224792e-03, -1.57542611462692145e-03, -3.05158628452478807e-03},
+    {-8.87678609044812990e-04, 3.83194388837734693e-04, 1.37779212442523083e-03},
+    {-2.11519042076831979e-03, 5.82337362515735358e-04, 2.24055108941204821e-04},
+    {4.61545125563611917e-04, 7.72869451707915893e-04, -1.10800630143346882e-03},
+    {1.05937484157345879e-03, -3.14448681732842211e-04, -1.75129182446198098e-03},
+    {1.49045689016363055e-03, -2.09220860101674106e-04, 5.93100338908187697e-04},
+    {-3.51246656293852696e-04, -8.20743017485394289e-04, 5.71854064480802862e-04},
+    {-9.18204643629581319e-01, -2.27788122702773155e-01, 6.39980793022790623e-02},
+    {9.24243491377523679e-05, 7.32841332381495400e-04, -1.55219718415109450e-03},
+    {7.13695056804217989e-04, -8.46467621879685712e-05, 6.50202947442505750e-04},
+    {1.66640864747485983e-03, -1.24492362771216523e-04, 2.68236502346156410e-04},
+    {-7.20253644860527516e-04, 7.81434220384157334e-04, 1.12661089007361367e-03},
+    {-6.83033334365238206e-05, 7.27742627159490762e-04, -1.78048843835204584e-03},
+    {-3.13431571993316588e-02, -8.57604034845650287e-01, -2.57225920656276863e-01},
+    {-6.47867200595898341e-05, -1.16688982572457655e-03, 1.14174511750260031e-03},
+    {-5.00713925613324338e-04, -6.87598082111323477e-04, 6.20598069880440176e-04},
+    {-8.56716727659588957e-05, 9.74478786593559361e-04, -1.65892838405139512e-03},
+    {6.53468478750158263e-04, 7.51662000672516676e-04, -6.73196326298856570e-04},
+    {-4.42539011000103941e-02, -2.01965359697350230e-02, -9.94663493761314355e-01},
+    {-7.39107395392403087e-04, 5.28870828612476996e-04, 1.00947183860234540e-03},
+    {-2.06577300933763214e-03, 9.60215813758718011e-04, -3.27993888180819421e-04},
+    {3.47783280638377555e-04, 8.41824316850705743e-04, -8.87458944147930993e-04},
+    {1.20960551709587905e+00, -7.07660818059813873e-02, -8.56332806008946491e-03},
+    {2.11116509318935269e-04, 7.68490846994171776e-04, -1.63228995491542417e-03},
+    {6.47698075356516103e-04, -4.20589129268072884e-04, 1.18354001300614896e-03},
+    {-2.78795945253848716e-02, 1.22199201000304547e+00, -2.07383075858847743e-01},
+    {-5.32457386680677347e-05, -9.58027320315790677e-04, 9.89667309649038679e-04},
+    {-9.03932426306289782e-02, -4.00969232187064692e-02, 1.26285611182120072e+00},
+    {-2.19453630740322871e-03, -1.21893190049422620e-03, -1.92293368093085417e-03},
+    {1.72950845415964505e-06, -8.93952511560151819e-09, -6.14874900641340649e-06},
+    {8.02644554976326974e-06, -6.42543741723487294e-06, -6.07103419227907060e-06},
+    {3.20307552755319525e-06, -4.83533743093466500e-06, 9.13563764113473065e-07},
+    {-2.18105804067510178e-06, 6.19595552598436322e-07, 5.21392855381760945e-06},
+    {-2.43310123604345563e-06, 2.17201813434465818e-06, 1.94098874242362718e-07},
+    {-1.56293672065252465e-06, 3.95256011818110372e-06, 1.68792962079201969e-06},
+    {-1.37567295252127852e-03, 3.59746071987262106e-04, 7.38927139000157259e-05},
+    {4.27822004137219658e-06, -8.80187479967658548e-07, 2.29453131891411977e-06},
+    {7.68758937964332534e-06, 2.40909410585557829e-07, 4.69351234070854509e-06},
+    {-2.87166709944317033e-06, 7.60223902901142716e-07, 4.57864913314467992e-06},
+    {-4.01295140267654560e-06, 2.65929275888376483e-06, -2.36575067819565221e-06},
+    {2.32693030513910805e-07, 2.28814396769890308e-06, 1.83526107699893970e-07},
+    {-2.18213927011287265e-03, 1.65013083920367864e-03, 2.31992998847323087e-04},
+    {-7.70829764693697905e-06, 4.23888841240673345e-07, 7.30018322002944087e-06},
+    {-1.23111329452911533e-06, 1.50076529718910084e-06, -1.91139744928209288e-06},
+    {-1.68872756433485760e-06, 1.03254236824697979e-06, -1.72081108163607555e-06},
+    {1.64276928199709460e-06, -4.96350219553231067e-07, -1.46349385185670297e-06},
+    {1.12731767057843682e-03, 5.03104281148445223e-04, 1.36398977654308994e-03},
+    {-1.05449609518089293e-06, -4.06952115309007489e-07, 3.53062441379482783e-06},
+    {-1.98745923822574166e-06, 4.98021943693208180e-07, 3.92645061370218429e-06},
+    {-1.55569377977005097e-07, -4.00262856484093037e-07, -2.49609122397048688e-06},
+    {2.18005022830924673e-03, -4.10275057064835439e-05, -2.59776311836759947e-04},
+    {5.41337439827552225e-07, -1.88603932528607146e-06, -2.06428606152470051e-06},
+    {-6.03243799807140491e-06, -3.75067864464502022e-06, -3.05702776851046742e-06},
+    {2.30038011634901016e-03, -1.32581161861259635e-03, -1.07680096899188406e-03},
+    {4.46773877910556887e-06, 1.85008408528524772e-08, -2.72851357570281713e-06},
+    {-1.49177636513049289e-03, -1.91426739654176659e-04, -1.71206384332753194e-03},
+    {2.31661325589237743e-02, 2.26540538563063554e-01, 5.42330337046266139e-02},
+    {-1.40563059963100256e-06, -4.50551806294901061e-06, 8.87542894832671347e-06},
+    {-1.66780916452391459e-06, 4.12065434881171526e-06, -3.55865035776836702e-06},
+    {2.71536622051954390e-07, -3.08564858926584692e-06, -1.52164363662402047e-06},
+    {2.66659632027280158e-06, -1.19436686895073481e-06, -3.25738306279285683e-06},
+    {-1.43666282346327501e-06, -2.51923473623639690e-06, 5.21205120344175876e-06},
+    {2.82954522469612199e-04, -1.59147454710008968e-03, 1.27685773978167098e-03},
+    {-3.99471240294241303e-06, 9.97323772325767188e-08, -5.28196823261495307e-06},
+    {-6.39858432699424995e-06, -4.59897864440506933e-06, -2.39736149785715891e-06},
+    {2.89457420106498109e-06, -3.10427512149489757e-06, 9.75553221437691631e-07},
+    {-8.96518259720091581e-07, -5.53996694461914366e-06, 1.03733964032237669e-05},
+    {8.82130497168875905e-04, -2.33618402105562365e-03, 1.35100410641244379e-03},
+    {-2.14088521029685841e-06, 2.59005410360388117e-06, -9.78713171504927426e-08},
+    {-4.50668337071552516e-06, 3.58808570076458002e-06, -1.56159349007541082e-06},
+    {-1.52345101244247272e-06, 2.21066768791959578e-06, -2.19555898547246775e-06},
+    {2.07334042074768356e-03, -1.56333498489329517e-03, -5.53762940364141767e-04},
+    {2.22151748134440108e-06, -4.74729938900429749e-07, -3.46744150304684889e-06},
+    {2.95389009221172505e-06, -2.96312023445686329e-06, -9.00385068308695580e-07},
+    {-6.47780848348620771e-04, 2.38772263398574292e-03, -8.93908589731968019e-04},
+    {9.69501567645025819e-07, 2.41432205872957328e-06, 5.56908291093893837e-07},
+    {-6.33392066185247586e-04, 2.38613844267241120e-03, -1.05383725637261472e-03},
+    {6.76250135616376785e-02, -5.57799579151454852e-02, 1.83393652374666566e-01},
+    {3.53986894266120067e-06, 5.92996717102502093e-06, -7.32378536156402804e-06},
+    {5.69667193362453916e-06, 1.20219201908705218e-06, -4.56663805956276925e-06},
+    {7.11494218295222192e-07, 2.93069858359131137e-06, 1.23210839732268429e-07},
+    {-3.41917893741799928e-06, -1.47435291776966751e-06, 1.07397354370819542e-06},
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+    {5.28852302228433047e-09, 6.47161005340457507e-09, -8.67298467766008940e-09},
+    {-2.25465519365641853e-07, -6.46057585221293529e-07, 3.48151143400587948e-07},
+    {-1.30051025504229756e-09, -3.25062288891730944e-09, 2.01775679498084060e-09},
+    {-5.12724809831333062e-09, 9.33902577666956280e-10, -6.96327353416625883e-10},
+    {-3.10810940873373909e-09, -7.49756534634826721e-10, 6.87357185058523612e-10},
+    {-1.52109221995821997e-06, -4.22908767925417317e-07, 1.38629667568307413e-06},
+    {1.42955317028459206e-09, -7.02968461219199980e-10, -3.81617160094549490e-09},
+    {2.53707400921232562e-09, -1.60727622877665510e-09, -4.18765366827500429e-09},
+    {-2.14750738948554787e-07, -6.40554276953864132e-07, 3.76128531993924486e-07},
+    {3.83073214815787821e-09, 4.50296289838947317e-10, 2.29523194894554194e-09},
+    {4.76340728555735282e-07, 6.83235613037347367e-07, -4.72205395646296822e-07},
+    {-6.10651996176347607e-04, -1.06790499934057291e-03, 2.29083496655867842e-03},
+    {3.95497823379997726e-09, 1.38236928154400474e-09, -6.26218820548585242e-09},
+    {1.11904936705986557e-09, -1.37869946362223494e-08, -9.34049783699042457e-10},
+    {1.25499246411697740e-09, -2.73635453185150368e-09, -2.91506864740637139e-09},
+    {-3.59882924006599270e-07, 1.32511373732895413e-06, -1.55110207063907657e-07},
+    {1.07068498511608823e-09, 8.92087770321126072e-09, 2.62826524433101838e-10},
+    {-2.69316546841480431e-09, 9.61138280075601870e-10, 5.19946977139973399e-09},
+    {-5.92563579700916554e-07, -1.05071339539294234e-06, 1.56249964602256375e-07},
+    {1.32198180180509439e-09, 5.16087961255351502e-09, 8.46339526239248130e-10},
+    {2.07323220008381881e-06, 1.02309267446332522e-06, -2.07661522726165781e-06},
+    {1.31402366846389393e-03, 3.78229792813366064e-04, 1.77496793932758741e-03},
+    {8.59301428624004160e-10, -6.83071707530125138e-09, 3.36249680876754553e-09},
+    {5.27310424491833629e-09, 2.09999085065692981e-08, -3.10459945807028959e-08},
+    {-8.88666080375855039e-08, 4.60897593930476024e-07, 7.41576575386676540e-07},
+    {-4.85540663230921155e-10, -5.58243438975036810e-09, 7.40450811775872353e-10},
+    {4.03141117225058743e-07, 1.52035531639227450e-06, 9.06206514897367477e-08},
+    {5.61075629915620496e-04, -2.05847905628765053e-03, 1.12849817492909434e-03},
+    {5.11216541321246609e-09, 7.26292920250060092e-09, -8.97145741030058730e-09},
+    {-4.26211688914213127e-07, -7.03366608210270750e-07, 6.27995585866791828e-07},
+    {1.15309052943982646e-03, 2.34474318844151959e-03, -4.91856748507475423e-03},
+    {1.01104427799588961e-01, -4.22361682938472982e-02, -1.88750007538552200e-01},
+    {3.94738332298860684e-10, -7.81372397340440727e-10, 4.06815717224340290e-09},
+    {-8.61483928638051566e-09, 5.37427180535843263e-09, 1.81738104426676372e-08},
+    {-8.48011268844706123e-10, -5.33803143354383280e-09, 2.99703953494934172e-10},
+    {3.89154099408092063e-07, -2.44166311268514957e-07, -8.03240371135063858e-07},
+    {-1.20249536439409610e-08, 1.48908931921210019e-08, 1.88292573199966284e-09},
+    {-1.16401289163015065e-08, 2.57866422936903206e-08, -5.27022399332555125e-09},
+    {1.37065399911928676e-07, 2.16494406102361175e-08, -7.63924557662179482e-07},
+    {-6.94754161319199870e-10, 6.65038621394664631e-09, -4.31779645371221932e-09},
+    {4.72542155592614588e-07, -7.58546986886782931e-07, -2.35913417925837088e-07},
+    {1.46133817312113241e-03, -3.25193103208258009e-04, -3.06625181254991741e-04},
+    {9.35794082672593210e-09, -7.92923574022275091e-09, -5.41426242728348939e-09},
+    {-2.15279239157428748e-08, -4.16754339024882903e-09, -1.12896482995505920e-08},
+    {2.60645369870582400e-10, 1.44616071127263122e-06, -3.63334053799999057e-07},
+    {9.17105741349288905e-09, -2.02295233654725681e-08, -1.20002956877085509e-08},
+    {-1.27759226226098477e-07, 1.28193771791124470e-06, -5.83097827522305323e-07},
+    {2.26880791869919426e-03, -1.34042850080092401e-03, -7.65092051285704835e-04},
+    {7.03374036792325796e-09, -2.53508958270032281e-09, -7.66132998708535240e-09},
+    {-9.71978722189015265e-07, -5.57836512454779054e-07, 1.96329328074063003e-06},
+    {-1.26115140811304343e-03, -4.81792074617704632e-04, -1.06803272537897391e-03},
+    {1.19419564863885497e-01, 5.07766738901840875e-02, 4.87642090320925953e-02},
+    {1.14090414893297520e-09, 1.56073433760228752e-08, -1.78054684078429726e-08},
+    {3.03285130343056153e-09, -1.58615337531031741e-09, -4.94928394101368241e-09},
+    {2.64483280249840080e-07, 2.97155396291660413e-07, -5.41608085095034164e-07},
+    {2.68757552324139226e-09, -1.41400907649469332e-08, 2.93255796729452456e-08},
+    {-2.11094617584561828e-07, -6.56355695552793272e-07, 3.72180321686621518e-07},
+    {-2.55073452371079590e-04, 1.57943859317488818e-03, -1.29154484940938240e-03},
+    {1.40049266628139435e-09, 1.40747080656922208e-08, -2.58792021839981956e-09},
+    {-2.12330362681090179e-07, -1.30522733223815968e-06, 5.84417623253341567e-07},
+    {-9.33144849909676392e-04, 1.90305575962152547e-03, -8.35564417983726418e-04},
+    {1.81624805201406961e-02, 6.84911174969819458e-02, -2.28291882522520390e-02},
+    {-8.25231299961259879e-09, -1.40227519596081152e-08, 1.78809529925716415e-08},
+    {1.90689491530449118e-07, 7.01057736002264065e-07, -4.26430629252294580e-07},
+    {-5.85146839837499930e-04, -1.07311215649546045e-03, 2.31986890222730339e-03},
+    {-1.05962397073886522e-01, 5.51532131360410807e-02, 1.87542648909451215e-01},
+    {-1.37499370823599516e-03, -8.49619409242363438e-04, -1.18180356709159952e-03}
+};
+
+static const double INTERCEPT[3] = {
+    -1.29208772400146188e+00,
+    6.62251952866635918e+00,
+    -1.35908984683965173e-01
+};
+// END AUTO-GENERATED COEFFICIENTS
+
+inline void compute_poly_features(const double x[7], double out[330]) {
+    for (int i = 0; i < N_FEATURES; ++i) {
+        double val = 1.0;
+        for (int j = 0; j < N_INPUTS; ++j) {
+            if (POWERS[i][j] != 0) {
+                double base = x[j];
+                int exp = POWERS[i][j];
+                // Fast integer exponentiation (max exp = 4)
+                double p = 1.0;
+                for (int e = 0; e < exp; ++e)
+                    p *= base;
+                val *= p;
+            }
+        }
+        out[i] = val;
+    }
+}
+
+} // namespace detail
+
+struct RGB {
+    unsigned char r, g, b;
+};
+
+/**
+ * Mix two RGB colors using polynomial pigment mixing.
+ *
+ * This performs polynomial pigment-style RGB interpolation.
+ *
+ * @param r1,g1,b1  First color (0-255)
+ * @param r2,g2,b2  Second color (0-255)
+ * @param t         Mixing ratio: 0.0 = all color1, 1.0 = all color2
+ * @param out_r,out_g,out_b  Output color (0-255)
+ */
+inline void lerp(unsigned char r1, unsigned char g1, unsigned char b1,
+                 unsigned char r2, unsigned char g2, unsigned char b2,
+                 float t,
+                 unsigned char* out_r, unsigned char* out_g, unsigned char* out_b) {
+    // Clamp t
+    if (t <= 0.0f) {
+        *out_r = r1; *out_g = g1; *out_b = b1;
+        return;
+    }
+    if (t >= 1.0f) {
+        *out_r = r2; *out_g = g2; *out_b = b2;
+        return;
+    }
+
+    double x[7] = {
+        static_cast<double>(r1), static_cast<double>(g1), static_cast<double>(b1),
+        static_cast<double>(r2), static_cast<double>(g2), static_cast<double>(b2),
+        static_cast<double>(t)
+    };
+
+    double features[330];
+    detail::compute_poly_features(x, features);
+
+    // Dot product: features @ COEF + INTERCEPT
+    for (int c = 0; c < 3; ++c) {
+        double sum = detail::INTERCEPT[c];
+        for (int i = 0; i < detail::N_FEATURES; ++i) {
+            sum += features[i] * detail::COEF[i][c];
+        }
+        // Clamp to [0, 255] and truncate (matches numpy astype(int) behavior)
+        int val = static_cast<int>(sum);
+        if (val < 0) val = 0;
+        if (val > 255) val = 255;
+
+        if (c == 0) *out_r = static_cast<unsigned char>(val);
+        else if (c == 1) *out_g = static_cast<unsigned char>(val);
+        else *out_b = static_cast<unsigned char>(val);
+    }
+}
+
+/**
+ * Convenience overload returning an RGB struct.
+ */
+inline RGB lerp(unsigned char r1, unsigned char g1, unsigned char b1,
+                unsigned char r2, unsigned char g2, unsigned char b2,
+                float t) {
+    RGB result;
+    lerp(r1, g1, b1, r2, g2, b2, t, &result.r, &result.g, &result.b);
+    return result;
+}
+
+} // namespace filament_mixer
+
+#endif // FILAMENT_MIXER_H

src/slic3r/CMakeLists.txt

@@ -373,6 +373,18 @@ set(SLIC3R_GUI_SOURCES
     GUI/FilamentGroupPopup.cpp
     GUI/PhysicalPrinterDialog.cpp
     GUI/PhysicalPrinterDialog.hpp
+    GUI/MixedGradientSelector.hpp
+    GUI/MixedGradientSelector.cpp
+    GUI/MixedGradientWeightsDialog.hpp
+    GUI/MixedGradientWeightsDialog.cpp
+    GUI/MixedFilamentColorMapPanel.hpp
+    GUI/MixedFilamentColorMapPanel.cpp
+    GUI/MixedFilamentColorMatchDialog.hpp
+    GUI/MixedFilamentColorMatchDialog.cpp
+    GUI/MixedMixPreview.hpp
+    GUI/MixedMixPreview.cpp
+    GUI/MixedFilamentConfigPanel.hpp
+    GUI/MixedFilamentConfigPanel.cpp
     GUI/Plater.cpp
     GUI/Plater.hpp
     GUI/PlateSettingsDialog.cpp

src/slic3r/GUI/3DScene.cpp

@@ -614,6 +614,9 @@ void GLVolume::simple_render(GLShaderProgram* shader, ModelObjectPtrs& model_obj
             if (shader) {
                 if (idx == 0) {
                     int extruder_id = model_volume->extruder_id();
+                    // Clamp to valid range; fall back to extruder 1 on overflow
+                    if (extruder_id <= 0 || extruder_id > (int)extruder_colors.size())
+                        extruder_id = 1;
                     //to make black not too hard too see
                     ColorRGBA new_color = adjust_color_for_rendering(extruder_colors[extruder_id - 1]);
                     if (ban_light) {
@@ -623,7 +626,7 @@ void GLVolume::simple_render(GLShaderProgram* shader, ModelObjectPtrs& model_obj
                     // shader->set_uniform("uniform_color", new_color);
                 }
                 else {
-                    if (idx <= extruder_colors.size()) {
+                    if (idx <= (int)extruder_colors.size()) {
                         //to make black not too hard too see
                         ColorRGBA new_color = adjust_color_for_rendering(extruder_colors[idx - 1]);
                         if (ban_light) {
@@ -854,7 +857,7 @@ int GLVolumeCollection::load_wipe_tower_preview(
     std::vector<int> plate_extruders = ppl.get_plate(plate_idx)->get_extruders(true);
     TriangleMesh wipe_tower_shell = make_cube(width, depth, height);
     for (int extruder_id : plate_extruders) {
-        if (extruder_id <= extruder_colors.size())
+        if (extruder_id >= 1 && extruder_id <= (int)extruder_colors.size())
             colors.push_back(extruder_colors[extruder_id - 1]);
         else
             colors.push_back(extruder_colors[0]);
@@ -895,8 +898,9 @@ int GLVolumeCollection::load_real_wipe_tower_preview(
     std::vector<int>                  plate_extruders  = ppl.get_plate(plate_idx)->get_extruders(true);
     std::vector<Slic3r::ColorRGBA>    colors;
     if (!plate_extruders.empty()) {
-        if (plate_extruders.front() <= extruder_colors.size())
-            colors.push_back(extruder_colors[plate_extruders.front() - 1]);
+        const int front_id = plate_extruders.front();
+        if (front_id >= 1 && front_id <= (int)extruder_colors.size())
+            colors.push_back(extruder_colors[front_id - 1]);
         else
             colors.push_back(extruder_colors[0]);
     }

src/slic3r/GUI/ConfigManipulation.cpp

@@ -479,20 +479,43 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
         }
     }
 
-    // BBS
-    static const char* keys[] = { "support_filament", "support_interface_filament"};
-    for (int i = 0; i < sizeof(keys) / sizeof(keys[0]); i++) {
-        std::string key = std::string(keys[i]);
+    // Rule 1:
+    // - support slots stay physical-only
+    // - feature slots (wall/infill/wipe tower) may use mixed virtual IDs
+    // Any out-of-range value is reset to 0.
+    {
+        static const char* support_slot_keys[] = {
+            "support_filament", "support_interface_filament"
+        };
+        static const char* feature_slot_keys[] = {
+            "wall_filament", "sparse_infill_filament", "solid_infill_filament", "wipe_tower_filament"
+        };
+
+        const size_t total    = wxGetApp().preset_bundle->total_filament_count();
+        const size_t num_phys = wxGetApp().preset_bundle->filament_presets.size();
+
+        for (auto key : support_slot_keys) {
             auto* opt = dynamic_cast<ConfigOptionInt*>(config->option(key, false));
-        if (opt != nullptr) {
-            if (opt->getInt() > filament_cnt) {
+            if (!opt)
+                continue;
+            const int val = opt->getInt();
+            const bool out_of_range = val < 0 || val > int(total);
+            const bool is_mixed     = val > int(num_phys) && val <= int(total);
+            if (out_of_range || is_mixed) {
                 DynamicPrintConfig new_conf = *config;
-                const DynamicPrintConfig *conf_temp = wxGetApp().plater()->config();
-                int new_value = 0;
-                if (conf_temp != nullptr && conf_temp->has(key)) {
-                    new_value = conf_temp->opt_int(key);
+                new_conf.set_key_value(key, new ConfigOptionInt(0));
+                apply(config, &new_conf);
             }
-                new_conf.set_key_value(key, new ConfigOptionInt(new_value));
+        }
+
+        for (auto key : feature_slot_keys) {
+            auto* opt = dynamic_cast<ConfigOptionInt*>(config->option(key, false));
+            if (!opt)
+                continue;
+            const int val = opt->getInt();
+            if (val < 0 || val > int(total)) {
+                DynamicPrintConfig new_conf = *config;
+                new_conf.set_key_value(key, new ConfigOptionInt(0));
                 apply(config, &new_conf);
             }
         }
@@ -541,6 +564,40 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
         apply(config, &new_conf);
         is_msg_dlg_already_exist = false;
     }
+
+    // Rule 2 — Local-Z dithering is incompatible with mixed-filament region collapse.
+    // When dithering_local_z_mode is on, force mixed_filament_region_collapse off.
+    if (config->has("dithering_local_z_mode") && config->has("mixed_filament_region_collapse") &&
+        config->opt_bool("dithering_local_z_mode") &&
+        config->opt_bool("mixed_filament_region_collapse")) {
+        DynamicPrintConfig new_conf = *config;
+        new_conf.set_key_value("mixed_filament_region_collapse", new ConfigOptionBool(false));
+        apply(config, &new_conf);
+    }
+
+    // Rule 3 — One-time warning when Local-Z dithering is enabled alongside variable layer height.
+    {
+        static bool s_local_z_varlay_warned = false;
+        bool dithering_on = config->has("dithering_local_z_mode") &&
+                            config->opt_bool("dithering_local_z_mode");
+        if (dithering_on && !s_local_z_varlay_warned) {
+            bool has_var = false;
+            for (const auto* obj : wxGetApp().plater()->model().objects)
+                if (obj->layer_height_profile.get().size() > 4) { has_var = true; break; }
+            if (has_var) {
+                MessageDialog dlg(m_msg_dlg_parent,
+                    _L("Using variable layer height together with Local-Z dithering "
+                       "may result in poor color mixing quality."),
+                    "", wxICON_WARNING | wxOK);
+                is_msg_dlg_already_exist = true;
+                dlg.ShowModal();
+                is_msg_dlg_already_exist = false;
+                s_local_z_varlay_warned = true;
+            }
+        }
+        if (!dithering_on)
+            s_local_z_varlay_warned = false;
+    }
 }
 
 void ConfigManipulation::apply_null_fff_config(DynamicPrintConfig *config, std::vector<std::string> const &keys, std::map<ObjectBase *, ModelConfig *> const &configs)
@@ -978,6 +1035,36 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, co
 
     std::string printer_type = wxGetApp().preset_bundle->printers.get_edited_preset().get_printer_type(wxGetApp().preset_bundle);
     toggle_line("enable_wrapping_detection", DevPrinterConfigUtil::support_wrapping_detection(printer_type));
+
+    // Mixed-filament / dithering visibility rules.
+    const bool local_z_dithering_on =
+        config->has("dithering_local_z_mode") && config->option("dithering_local_z_mode") != nullptr &&
+        config->opt_bool("dithering_local_z_mode");
+    toggle_line("dithering_local_z_whole_objects",     local_z_dithering_on);
+    toggle_line("dithering_local_z_direct_multicolor", local_z_dithering_on);
+
+    // local_z_wipe_tower_purge_lines: only when prime tower + local-Z + non-BBL
+    toggle_line("local_z_wipe_tower_purge_lines",
+        config->has("enable_prime_tower") && config->opt_bool("enable_prime_tower") &&
+        local_z_dithering_on && !is_BBL_Printer);
+
+    // mixed_filament_surface_indentation only when bias is enabled
+    const bool component_bias_enabled =
+        config->has("mixed_filament_component_bias_enabled") &&
+        config->option("mixed_filament_component_bias_enabled") != nullptr &&
+        config->opt_bool("mixed_filament_component_bias_enabled");
+    toggle_line("mixed_filament_surface_indentation", component_bias_enabled);
+
+    // infill override sub-options gated by enable_infill_filament_override
+    const bool show_infill_filament_override_v =
+        !is_global_config && have_infill && !bSEMM;
+    const bool show_infill_filament_details_v =
+        show_infill_filament_override_v &&
+        config->has("enable_infill_filament_override") &&
+        config->option("enable_infill_filament_override") != nullptr &&
+        config->opt_bool("enable_infill_filament_override");
+    toggle_line("infill_filament_use_base_first_layers", show_infill_filament_details_v);
+    toggle_line("infill_filament_use_base_last_layers",  show_infill_filament_details_v);
 }
 
 void ConfigManipulation::update_print_sla_config(DynamicPrintConfig* config, const bool is_global_config/* = false*/)

src/slic3r/GUI/ExtraRenderers.cpp

@@ -263,6 +263,33 @@ bool BitmapChoiceRenderer::GetValue(wxVariant& value) const
     return true;
 }
 
+static std::vector<wxBitmap*> mixed_aware_extruder_icons(bool thin_icon = false)
+{
+    std::vector<wxBitmap*> icons = get_extruder_color_icons(thin_icon);
+
+    if (Slic3r::GUI::wxGetApp().plater() == nullptr)
+        return icons;
+
+    const std::vector<std::string> all_colors =
+        Slic3r::GUI::wxGetApp().plater()->get_extruder_colors_from_plater_config(nullptr, true);
+    if (all_colors.size() <= icons.size())
+        return icons;
+
+    const double em = Slic3r::GUI::wxGetApp().em_unit();
+    const int    icon_width  = int((thin_icon ? 2.0 : 4.4) * em + 0.5);
+    const int    icon_height = int(2.0 * em + 0.5);
+    for (size_t idx = icons.size(); idx < all_colors.size(); ++idx) {
+        if (all_colors[idx].empty()) {
+            icons.push_back(nullptr);
+            continue;
+        }
+
+        icons.push_back(get_extruder_color_icon(all_colors[idx], std::to_string(idx + 1), icon_width, icon_height));
+    }
+
+    return icons;
+}
+
 bool BitmapChoiceRenderer::Render(wxRect rect, wxDC* dc, int state)
 {
     const wxBitmap& icon = m_value.GetBitmap();
@@ -301,7 +328,7 @@ wxWindow* BitmapChoiceRenderer::CreateEditorCtrl(wxWindow* parent, wxRect labelR
     if (can_create_editor_ctrl && !can_create_editor_ctrl())
         return nullptr;
 
-    std::vector<wxBitmap*> icons = get_extruder_color_icons();
+    std::vector<wxBitmap*> icons = mixed_aware_extruder_icons(false);
     if (icons.empty())
         return nullptr;
 
@@ -317,12 +344,14 @@ wxWindow* BitmapChoiceRenderer::CreateEditorCtrl(wxWindow* parent, wxRect labelR
         c_editor->Append(_L("default"), *get_default_extruder_color_icon());
 
     for (size_t i = 0; i < icons.size(); i++)
-        c_editor->Append(wxString::Format("%d", i+1), *icons[i]);
+        c_editor->Append(wxString::Format("%d", i + 1), icons[i] ? *icons[i] : wxNullBitmap);
 
-    if (has_default_extruder && has_default_extruder())
-        c_editor->SetSelection(atoi(data.GetText().c_str()));
-    else
-        c_editor->SetSelection(atoi(data.GetText().c_str()) - 1);
+    int selection = (has_default_extruder && has_default_extruder())
+        ? atoi(data.GetText().c_str())
+        : atoi(data.GetText().c_str()) - 1;
+    if (selection < 0 || selection >= int(c_editor->GetCount()))
+        selection = 0;
+    c_editor->SetSelection(selection);
 
     c_editor->Bind(wxEVT_SET_FOCUS, [c_editor](wxFocusEvent& evt) {
 #ifdef __WXGTK__

src/slic3r/GUI/GLCanvas3D.cpp

@@ -2561,7 +2561,8 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
             if (!model_volume.is_model_part())
                 continue;
 
-            unsigned int filaments_count = (unsigned int)dynamic_cast<const ConfigOptionStrings*>(m_config->option("filament_colour"))->values.size();
+            unsigned int filament_colour_size = (unsigned int)dynamic_cast<const ConfigOptionStrings*>(m_config->option("filament_colour"))->values.size();
+            unsigned int filaments_count = std::max(filament_colour_size, (unsigned int)wxGetApp().preset_bundle->total_filament_count());
             model_volume.update_extruder_count(filaments_count);
         }
     }
@@ -2831,6 +2832,23 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
 				volume->set_sla_shift_z(shift_zs[volume->object_idx()]);
     }
 
+    // BBS: single-extruder mixed filament risk notification
+    if (printer_technology == ptFFF && wxGetApp().preset_bundle) {
+        const size_t total_filaments = wxGetApp().preset_bundle->total_filament_count();
+        const size_t num_phys        = wxGetApp().preset_bundle->filament_presets.size();
+        const bool   any_mixed       = total_filaments > num_phys;
+        auto* printer_extruder_id_opt = wxGetApp().preset_bundle->printers.get_edited_preset()
+                                            .config.option<ConfigOptionInts>("printer_extruder_id");
+        const int printer_extruders_count = printer_extruder_id_opt ? (int)printer_extruder_id_opt->values.size() : 1;
+        auto& nm = *wxGetApp().plater()->get_notification_manager();
+        if (printer_extruders_count == 1 && any_mixed)
+            nm.push_notification(NotificationType::BBLSingleExtruderMixedFilamentRisk,
+                                 NotificationManager::NotificationLevel::WarningNotificationLevel,
+                                 _u8L("Mixed filaments are unreliable on a single-extruder printer."));
+        else
+            nm.close_notification_of_type(NotificationType::BBLSingleExtruderMixedFilamentRisk);
+    }
+
     // BBS
     if (printer_technology == ptFFF && m_config->has("filament_colour") && (m_canvas_type != ECanvasType::CanvasAssembleView)) {
         // Should the wipe tower be visualized ?

src/slic3r/GUI/GUI_App.cpp

@@ -75,6 +75,7 @@
 #include "libslic3r/miniz_extension.hpp"
 #include "libslic3r/Utils.hpp"
 #include "libslic3r/Color.hpp"
+#include "libslic3r/MixedFilament.hpp"
 
 #include "GUI.hpp"
 #include "GUI_Utils.hpp"
@@ -2950,6 +2951,11 @@ bool GUI_App::on_init_inner()
     // BBS if load user preset failed
     //if (loaded_preset_result != 0) {
         try {
+            // Apply the user's auto_generate_gradients preference before load_presets
+            // triggers PresetBundle::sync_mixed_filaments_from_config, which calls
+            // MixedFilamentManager::auto_generate. The static atomic defaults to true,
+            // so without this the preference is ignored on the initial preset load.
+            MixedFilamentManager::set_auto_generate_enabled(app_config->get_bool("auto_generate_gradients"));
             // Enable all substitutions (in both user and system profiles), but log the substitutions in user profiles only.
             // If there are substitutions in system profiles, then a "reconfigure" event shall be triggered, which will force
             // installation of a compatible system preset, thus nullifying the system preset substitutions.

src/slic3r/GUI/GUI_Factories.cpp

@@ -35,9 +35,53 @@ static PrinterTechnology printer_technology()
     return wxGetApp().preset_bundle->printers.get_selected_preset().printer_technology();
 }
 
+static int physical_filaments_count()
+{
+    return std::max(wxGetApp().filaments_cnt(), 0);
+}
+
 static int filaments_count()
 {
-    return wxGetApp().filaments_cnt();
+    if (wxGetApp().preset_bundle == nullptr)
+        return 0;
+    const int physical = physical_filaments_count();
+    const auto &mixed_mgr = wxGetApp().preset_bundle->mixed_filaments;
+    return static_cast<int>(mixed_mgr.total_filaments(size_t(physical)));
+}
+
+static std::vector<unsigned int> ui_ordered_filament_ids()
+{
+    if (wxGetApp().plater() == nullptr)
+        return {};
+    return wxGetApp().plater()->sidebar().get_ui_ordered_filament_ids();
+}
+
+static wxString filament_menu_item_name(const int filament_id_1based)
+{
+    if (filament_id_1based <= 0)
+        return _L("Default");
+
+    if (wxGetApp().preset_bundle == nullptr)
+        return wxString::Format(_L("Filament %d"), filament_id_1based);
+
+    const int physical = physical_filaments_count();
+    if (filament_id_1based <= physical) {
+        const size_t preset_idx = size_t(filament_id_1based - 1);
+        const auto  &filament_presets = wxGetApp().preset_bundle->filament_presets;
+        if (preset_idx < filament_presets.size()) {
+            auto preset = wxGetApp().preset_bundle->filaments.find_preset(filament_presets[preset_idx]);
+            if (preset != nullptr)
+                return from_u8(preset->label(false));
+        }
+        return wxString::Format(_L("Filament %d"), filament_id_1based);
+    }
+
+    const auto &mgr = wxGetApp().preset_bundle->mixed_filaments;
+    const MixedFilament *mixed = mgr.mixed_filament_from_id(unsigned(filament_id_1based), size_t(physical));
+    if (mixed == nullptr)
+        return _L("Mixed Filament");
+
+    return from_u8(mixed_filament_standardized_name(*mixed, size_t(physical)));
 }
 
 static bool is_improper_category(const std::string& category, const int filaments_cnt, const bool is_object_settings = true)
@@ -1042,8 +1086,9 @@ void MenuFactory::append_menu_item_change_extruder(wxMenu* menu)
             menu->Destroy(item_id);
     }
 
-    const int filaments_cnt = filaments_count();
-    if (filaments_cnt <= 1)
+    // Use UI-ordered filament IDs (physical first, then enabled mixed in UI order)
+    const std::vector<unsigned int> ordered_filament_ids = ui_ordered_filament_ids();
+    if (ordered_filament_ids.size() <= 1)
         return;
 
     wxDataViewItemArray sels;
@@ -1059,24 +1104,16 @@ void MenuFactory::append_menu_item_change_extruder(wxMenu* menu)
     if (sels.Count() == 1) {
         const ModelConfig& config = obj_list()->get_item_config(sels[0]);
         // BBS: set default extruder to 1
-        initial_extruder = config.has("extruder") ? config.extruder() : 1;
+        initial_extruder = config.has("extruder") ? config.extruder() : 0;
     }
 
-    for (int i = 0; i <= filaments_cnt; i++)
+    for (size_t display_idx = 0; display_idx <= ordered_filament_ids.size(); ++display_idx)
     {
-        bool is_active_extruder = i == initial_extruder;
-        int icon_idx = i == 0 ? 0 : i - 1;
+        const int actual_filament_id = display_idx == 0 ? 0 : int(ordered_filament_ids[display_idx - 1]);
+        const bool is_active_extruder = actual_filament_id == initial_extruder;
+        const int icon_idx = actual_filament_id == 0 ? 0 : actual_filament_id - 1;
 
-        wxString item_name = _L("Default");
-
-        if (i > 0) {
-            auto preset = wxGetApp().preset_bundle->filaments.find_preset(wxGetApp().preset_bundle->filament_presets[i - 1]);
-            if (preset == nullptr) {
-                item_name = wxString::Format(_L("Filament %d"), i);
-            } else {
-                item_name = from_u8(preset->label(false));
-            }
-        }
+        wxString item_name = filament_menu_item_name(actual_filament_id);
 
         if (is_active_extruder) {
             item_name << " (" + _L("current") + ")";
@@ -1084,11 +1121,13 @@ void MenuFactory::append_menu_item_change_extruder(wxMenu* menu)
 
         if (icon_idx >= 0 && icon_idx < icons.size()) {
             append_menu_item(
-                extruder_selection_menu, wxID_ANY, item_name, "", [i](wxCommandEvent &) { obj_list()->set_extruder_for_selected_items(i); }, *icons[icon_idx], menu,
+                extruder_selection_menu, wxID_ANY, item_name, "",
+                [actual_filament_id](wxCommandEvent &) { obj_list()->set_extruder_for_selected_items(actual_filament_id); }, *icons[icon_idx], menu,
                 [is_active_extruder]() { return !is_active_extruder; }, m_parent);
         } else {
             append_menu_item(
-                extruder_selection_menu, wxID_ANY, item_name, "", [i](wxCommandEvent &) { obj_list()->set_extruder_for_selected_items(i); }, "", menu,
+                extruder_selection_menu, wxID_ANY, item_name, "",
+                [actual_filament_id](wxCommandEvent &) { obj_list()->set_extruder_for_selected_items(actual_filament_id); }, "", menu,
                 [is_active_extruder]() { return !is_active_extruder; }, m_parent);
         }
     }
@@ -2213,8 +2252,8 @@ void MenuFactory::append_menu_item_change_filament(wxMenu* menu)
             menu->Destroy(item_id);
     }
 
-    int filaments_cnt = filaments_count();
-    if (filaments_cnt <= 1)
+    const std::vector<unsigned int> ordered_filament_ids = ui_ordered_filament_ids();
+    if (ordered_filament_ids.size() <= 1)
         return;
 
     wxDataViewItemArray sels;
@@ -2229,12 +2268,10 @@ void MenuFactory::append_menu_item_change_filament(wxMenu* menu)
     }
 
     std::vector<wxBitmap*> icons = get_extruder_color_icons(true);
-    if (icons.size() < filaments_cnt) {
-        BOOST_LOG_TRIVIAL(warning) << boost::format("Warning: icons size %1%, filaments_cnt=%2%")%icons.size()%filaments_cnt;
+    if (icons.size() < ordered_filament_ids.size()) {
+        BOOST_LOG_TRIVIAL(warning) << boost::format("Warning: icons size %1%, filaments_cnt=%2%") % icons.size() % ordered_filament_ids.size();
         if (icons.size() <= 1)
             return;
-        else
-            filaments_cnt = icons.size();
     }
     wxMenu* extruder_selection_menu = new wxMenu();
     const wxString& name = sels.Count() == 1 ? names[0] : names[1];
@@ -2242,46 +2279,27 @@ void MenuFactory::append_menu_item_change_filament(wxMenu* menu)
     int initial_extruder = -1; // negative value for multiple object/part selection
     if (sels.Count() == 1) {
         const ModelConfig& config = obj_list()->get_item_config(sels[0]);
-        // BBS
         const auto sel_vol = obj_list()->get_selected_model_volume();
         if (sel_vol && sel_vol->type() == ModelVolumeType::PARAMETER_MODIFIER)
             initial_extruder = config.has("extruder") ? config.extruder() : 0;
         else
-            initial_extruder = config.has("extruder") ? config.extruder() : 1;
+            initial_extruder = config.has("extruder") ? config.extruder() : 0;
     }
 
-    // BBS
-    bool has_modifier = false;
-    for (auto sel : sels) {
-        if (obj_list()->GetModel()->GetVolumeType(sel) == ModelVolumeType::PARAMETER_MODIFIER) {
-            has_modifier = true;
-            break;
-        }
-    }
-
-    for (int i = has_modifier ? 0 : 1; i <= filaments_cnt; i++)
+    for (size_t display_idx = 0; display_idx <= ordered_filament_ids.size(); ++display_idx)
     {
-        // BBS
-        //bool is_active_extruder = i == initial_extruder;
+        const int actual_filament_id = display_idx == 0 ? 0 : int(ordered_filament_ids[display_idx - 1]);
         bool is_active_extruder = false;
 
-        wxString item_name = _L("Default");
-
-        if (i > 0) {
-            auto preset = wxGetApp().preset_bundle->filaments.find_preset(wxGetApp().preset_bundle->filament_presets[i - 1]);
-            if (preset == nullptr) {
-                item_name = wxString::Format(_L("Filament %d"), i);
-            } else {
-                item_name = from_u8(preset->label(false));
-            }
-        }
+        wxString item_name = filament_menu_item_name(actual_filament_id);
 
         if (is_active_extruder) {
             item_name << " (" + _L("current") + ")";
         }
 
         append_menu_item(extruder_selection_menu, wxID_ANY, item_name, "",
-            [i](wxCommandEvent&) { obj_list()->set_extruder_for_selected_items(i); }, i == 0 ? wxNullBitmap : *icons[i - 1], menu,
+            [actual_filament_id](wxCommandEvent&) { obj_list()->set_extruder_for_selected_items(actual_filament_id); },
+            actual_filament_id == 0 || size_t(actual_filament_id - 1) >= icons.size() ? wxNullBitmap : *icons[size_t(actual_filament_id - 1)], menu,
             [is_active_extruder]() { return !is_active_extruder; }, m_parent);
     }
     menu->Append(wxID_ANY, name, extruder_selection_menu, _L("Change Filament"));

src/slic3r/GUI/GUI_ObjectList.cpp

@@ -1,4 +1,5 @@
 #include "libslic3r/libslic3r.h"
+#include "libslic3r/MixedFilament.hpp"
 #include "libslic3r/PresetBundle.hpp"
 #include "GUI_ObjectList.hpp"
 #include "GUI_Factories.hpp"
@@ -75,9 +76,20 @@ static DynamicPrintConfig& printer_config()
     return wxGetApp().preset_bundle->printers.get_edited_preset().config;
 }
 
+static size_t total_filaments_count(size_t physical_count)
+{
+    if (wxGetApp().preset_bundle == nullptr)
+        return physical_count;
+
+    return wxGetApp().preset_bundle->mixed_filaments.total_filaments(physical_count);
+}
+
 static int filaments_count()
 {
-    return wxGetApp().filaments_cnt();
+    if (wxGetApp().preset_bundle == nullptr)
+        return 0;
+
+    return static_cast<int>(total_filaments_count(size_t(std::max(wxGetApp().filaments_cnt(), 0))));
 }
 
 static void take_snapshot(const std::string& snapshot_name)
@@ -1000,16 +1012,18 @@ void ObjectList::update_objects_list_filament_column(size_t filaments_count)
     if (printer_technology() == ptSLA)
         filaments_count = 1;
 
+    const size_t total_filaments = total_filaments_count(filaments_count);
+
     m_prevent_update_filament_in_config = true;
 
-    // BBS: update extruder values even when filaments_count is 1, because it may be reduced from value greater than 1
+    // Orca: update extruder values even when total_filaments is 1, because it may be reduced from value greater than 1
     if (m_objects)
-        update_filament_values_for_items(filaments_count);
+        update_filament_values_for_items(total_filaments);
 
     update_filament_colors();
 
     // set show/hide for this column
-    set_filament_column_hidden(filaments_count == 1);
+    set_filament_column_hidden(total_filaments == 1);
     //a workaround for a wrong last column width updating under OSX
     auto em = em_unit(this);
     GetColumn(colEditing)->SetWidth(m_columns_width[colEditing]*em);
@@ -1020,6 +1034,7 @@ void ObjectList::update_objects_list_filament_column(size_t filaments_count)
 void ObjectList::update_objects_list_filament_column_when_delete_filament(size_t filament_id, size_t filaments_count, int replace_filament_id)
 {
     m_prevent_update_filament_in_config = true;
+    size_t total_filaments = total_filaments_count(filaments_count);
 
     // BBS: update extruder values even when filaments_count is 1, because it may be reduced from value greater than 1
     if (m_objects)
@@ -1028,7 +1043,7 @@ void ObjectList::update_objects_list_filament_column_when_delete_filament(size_t
     update_filament_colors();
 
     // set show/hide for this column
-    set_filament_column_hidden(filaments_count == 1);
+    set_filament_column_hidden(total_filaments == 1);
     // a workaround for a wrong last column width updating under OSX
     GetColumn(colEditing)->SetWidth(25);
 
@@ -6536,9 +6551,9 @@ void ObjectList::OnEditingDone(wxDataViewEvent &event)
 // BBS: remove "const" qualifier
 void ObjectList::set_extruder_for_selected_items(const int extruder)
 {
-    // BBS: check extruder id
-    std::vector<std::string> colors = wxGetApp().plater()->get_extruder_colors_from_plater_config();
-    if (extruder > colors.size())
+    // Accept any configured filament id, including mixed virtual filaments.
+    const int max_filaments = filaments_count();
+    if (extruder < 0 || extruder > max_filaments)
         return;
 
     wxDataViewItemArray sels;

src/slic3r/GUI/GUI_ObjectTable.cpp

@@ -2804,55 +2804,69 @@ int ObjectTablePanel::init_bitmap()
     m_undo_bitmap = create_scaled_bitmap("lock_normal", nullptr, 18);
     m_color_bitmaps = get_extruder_color_icons();
 
+    const std::vector<std::string> all_colors = wxGetApp().plater()->get_extruder_colors_from_plater_config(nullptr, true);
+    if (all_colors.size() > m_color_bitmaps.size()) {
+        const double em = wxGetApp().em_unit();
+        const int    icon_width  = int(4.4 * em + 0.5);
+        const int    icon_height = int(2.0 * em + 0.5);
+        for (size_t idx = m_color_bitmaps.size(); idx < all_colors.size(); ++idx) {
+            if (all_colors[idx].empty()) {
+                m_color_bitmaps.push_back(nullptr);
+                continue;
+            }
+
+            m_color_bitmaps.push_back(get_extruder_color_icon(all_colors[idx], std::to_string(idx + 1), icon_width, icon_height));
+        }
+    }
+
     return 0;
 }
 
 int ObjectTablePanel::init_filaments_and_colors()
 {
-    //DynamicPrintConfig&  global_config   = wxGetApp().preset_bundle->prints.get_edited_preset().config;
-    const DynamicPrintConfig* global_config = m_plater->config();
     const std::vector<std::string> filament_presets = wxGetApp().preset_bundle->filament_presets;
-    m_filaments_count = filament_presets.size();
+    const std::vector<std::string> filament_colors  = wxGetApp().plater()->get_extruder_colors_from_plater_config(nullptr, true);
+    m_filaments_count = filament_colors.size();
     if (m_filaments_count <= 0) {
         BOOST_LOG_TRIVIAL(error) << __FUNCTION__ << boost::format(", can not get filaments, count: %1%, set to default") % m_filaments_count;
         set_default_filaments_and_colors();
         return -1;
     }
 
-    const ConfigOptionStrings* filament_opt = dynamic_cast<const ConfigOptionStrings*>(global_config->option("filament_colour"));
-    if (filament_opt == nullptr) {
-        set_default_filaments_and_colors();
-        return -1;
-    }
     m_filaments_colors.resize(m_filaments_count);
     m_filaments_name.resize(m_filaments_count);
-    unsigned int color_count = filament_opt->values.size();
-    if (color_count != m_filaments_count) {
-        BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << boost::format(", invalid color count:%1%, extruder count: %2%") %color_count %m_filaments_count;
-    }
-
-    unsigned int i = 0;
+    const size_t physical_count = filament_presets.size();
     ColorRGB rgb;
-    while (i < m_filaments_count) {
-        const std::string& txt_color = global_config->opt_string("filament_colour", i);
-        if (i < color_count) {
-            if (decode_color(txt_color, rgb))
-            {
+
+    for (int i = 0; i < (int)m_filaments_count; ++i) {
+        if (size_t(i) < filament_colors.size() && decode_color(filament_colors[size_t(i)], rgb))
             m_filaments_colors[i] = wxColour(rgb.r_uchar(), rgb.g_uchar(), rgb.b_uchar());
-            }
         else
-            {
-                m_filaments_colors[i] = *wxGREEN;
-            }
-        }
-        else {
             m_filaments_colors[i] = *wxGREEN;
+
+        if (size_t(i) < physical_count) {
+            m_filaments_name[i] = wxString(std::to_string(i + 1) + ": " + filament_presets[size_t(i)]);
+            continue;
         }
 
-        //parse the filaments
-        m_filaments_name[i] = wxString(std::to_string(i+1) + ": " + filament_presets[i]);
+        // Mixed-slot row: walk the manager and find the (physical_count + offset)-th enabled, non-deleted entry.
+        size_t mixed_offset = 0;
+        for (const MixedFilament &mf : wxGetApp().preset_bundle->mixed_filaments.mixed_filaments()) {
+            if (!mf.enabled || mf.deleted)
+                continue;
+            if (size_t(i) != physical_count + mixed_offset) {
+                ++mixed_offset;
+                continue;
+            }
 
-        i++;
+            m_filaments_name[i] = wxString::Format("%d: %s",
+                                                   i + 1,
+                                                   from_u8(mixed_filament_standardized_name(mf, physical_count)));
+            break;
+        }
+
+        if (m_filaments_name[i].empty())
+            m_filaments_name[i] = wxString::Format("%d: Filament %d", i + 1, i + 1);
     }
 
     return 0;

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.cpp

@@ -179,13 +179,14 @@ void GLGizmoMmuSegmentation::data_changed(bool is_serializing)
 
     ModelObject* model_object = m_c->selection_info()->model_object();
     int prev_extruders_count = int(m_extruders_colors.size());
-    if (prev_extruders_count != wxGetApp().filaments_cnt()) {
-        if (wxGetApp().filaments_cnt() > int(GLGizmoMmuSegmentation::EXTRUDERS_LIMIT))
+    int cur_filaments_count  = int(wxGetApp().preset_bundle->total_filament_count());
+    if (prev_extruders_count != cur_filaments_count) {
+        if (cur_filaments_count > int(GLGizmoMmuSegmentation::EXTRUDERS_LIMIT))
             show_notification_extruders_limit_exceeded();
 
         this->init_extruders_data();
         // Reinitialize triangle selectors because of change of extruder count need also change the size of GLIndexedVertexArray
-        if (prev_extruders_count != wxGetApp().filaments_cnt())
+        if (prev_extruders_count != int(m_extruders_colors.size()))
             this->init_model_triangle_selectors();
     } else if (wxGetApp().plater()->get_extruders_colors() != m_extruders_colors) {
         this->init_extruders_data();
@@ -433,7 +434,8 @@ void GLGizmoMmuSegmentation::on_render_input_window(float x, float y, float bott
             m_selected_extruder_idx = extruder_idx;
         }
 
-        if (extruder_idx < 16 && ImGui::IsItemHovered()) m_imgui->tooltip(_L("Shortcut Key ") + std::to_string(extruder_idx + 1), max_tooltip_width);
+        if (extruder_idx < int(GLGizmoMmuSegmentation::EXTRUDERS_LIMIT) && ImGui::IsItemHovered())
+            m_imgui->tooltip(_L("Shortcut Key ") + std::to_string(extruder_idx + 1), max_tooltip_width);
     }
     // ORCA: Remap filaments section (Border only, Title in border). 
     // Styled as a panel for visual grouping.
@@ -731,6 +733,8 @@ void GLGizmoMmuSegmentation::init_model_triangle_selectors()
             continue;
 
         int extruder_idx = (mv->extruder_id() > 0) ? mv->extruder_id() - 1 : 0;
+        extruder_idx = std::min(extruder_idx, (int)m_extruders_colors.size() - 1);
+        if (extruder_idx < 0) extruder_idx = 0;
         std::vector<ColorRGBA> ebt_colors;
         ebt_colors.push_back(m_extruders_colors[size_t(extruder_idx)]);
         ebt_colors.insert(ebt_colors.end(), m_extruders_colors.begin(), m_extruders_colors.end());
@@ -753,6 +757,7 @@ void GLGizmoMmuSegmentation::update_triangle_selectors_colors()
         TriangleSelectorPatch* selector = dynamic_cast<TriangleSelectorPatch*>(m_triangle_selectors[i].get());
         int extruder_idx = m_volumes_extruder_idxs[i];
         int extruder_color_idx = std::max(0, extruder_idx - 1);
+        extruder_color_idx = std::min(extruder_color_idx, (int)m_extruders_colors.size() - 1);
         std::vector<ColorRGBA> ebt_colors;
         ebt_colors.push_back(m_extruders_colors[extruder_color_idx]);
         ebt_colors.insert(ebt_colors.end(), m_extruders_colors.begin(), m_extruders_colors.end());
@@ -767,7 +772,8 @@ void GLGizmoMmuSegmentation::update_from_model_object(bool first_update)
     // Extruder colors need to be reloaded before calling init_model_triangle_selectors to render painted triangles
     // using colors from loaded 3MF and not from printer profile in Slicer.
     if (int prev_extruders_count = int(m_extruders_colors.size());
-        prev_extruders_count != wxGetApp().filaments_cnt() || wxGetApp().plater()->get_extruders_colors() != m_extruders_colors)
+        prev_extruders_count != int(wxGetApp().preset_bundle->total_filament_count()) ||
+        wxGetApp().plater()->get_extruders_colors() != m_extruders_colors)
         this->init_extruders_data();
 
     this->init_model_triangle_selectors();

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.hpp

@@ -72,11 +72,8 @@ public:
 
     void data_changed(bool is_serializing) override;
 
-    // TriangleSelector::serialization/deserialization has a limit to store 19 different states.
-    // EXTRUDER_LIMIT + 1 states are used to storing the painting because also uncolored triangles are stored.
-    // When increasing EXTRUDER_LIMIT, it needs to ensure that TriangleSelector::serialization/deserialization
-    // will be also extended to support additional states, requiring at least one state to remain free out of 19 states.
-    static const constexpr size_t EXTRUDERS_LIMIT = 16;
+    // Keep the paint gizmo limit aligned with TriangleSelector state capacity.
+    static const constexpr size_t EXTRUDERS_LIMIT = static_cast<size_t>(EnforcerBlockerType::ExtruderMax);
 
     const float get_cursor_radius_min() const override { return CursorRadiusMin; }
 

src/slic3r/GUI/Gizmos/GLGizmosManager.cpp

@@ -998,16 +998,42 @@ bool GLGizmosManager::on_key(wxKeyEvent& evt)
                     keyCode = keyCode- WXK_NUMPAD0+'0';
                 }
                 if (keyCode >= '0' && keyCode <= '9') {
-                    if (keyCode == '1' && !m_timer_set_color.IsRunning()) {
+                    const int digit = keyCode - '0';
+                    const int shortcut_max = int(GLGizmoMmuSegmentation::EXTRUDERS_LIMIT);
+                    auto select_shortcut = [mmu_seg](int number) {
+                        return number > 0 && mmu_seg->on_number_key_down(number);
+                    };
+
+                    if (m_timer_set_color.IsRunning() && m_pending_color_shortcut_tens > 0) {
+                        const int two_digit_shortcut = m_pending_color_shortcut_tens * 10 + digit;
+                        if (two_digit_shortcut <= shortcut_max) {
+                            processed = select_shortcut(two_digit_shortcut);
+                            m_pending_color_shortcut_tens = 0;
+                            m_timer_set_color.Stop();
+                        } else {
+                            // Fall back to the pending single-digit shortcut and then process current digit as fresh input.
+                            processed = select_shortcut(m_pending_color_shortcut_tens);
+                            m_pending_color_shortcut_tens = 0;
+                            m_timer_set_color.Stop();
+
+                            const bool can_start_two_digit = digit > 0 && digit * 10 <= shortcut_max;
+                            if (can_start_two_digit) {
+                                m_pending_color_shortcut_tens = digit;
                                 m_timer_set_color.StartOnce(500);
                                 processed = true;
+                            } else {
+                                processed = select_shortcut(digit) || processed;
                             }
-                    else if (keyCode < '7' && m_timer_set_color.IsRunning()) {
-                        processed = mmu_seg->on_number_key_down(keyCode - '0'+10);
-                        m_timer_set_color.Stop();
                         }
-                    else {
-                        processed = mmu_seg->on_number_key_down(keyCode - '0');
+                    } else {
+                        const bool can_start_two_digit = digit > 0 && digit * 10 <= shortcut_max;
+                        if (can_start_two_digit) {
+                            m_pending_color_shortcut_tens = digit;
+                            m_timer_set_color.StartOnce(500);
+                            processed = true;
+                        } else {
+                            processed = select_shortcut(digit);
+                        }
                     }
                 }
                 else if (keyCode == 'F' || keyCode == 'T' || keyCode == 'S' || keyCode == 'C' || keyCode == 'H' || keyCode == 'G') {
@@ -1054,12 +1080,15 @@ bool GLGizmosManager::on_key(wxKeyEvent& evt)
 
 void GLGizmosManager::on_set_color_timer(wxTimerEvent& evt)
 {
-    if (m_current == MmSegmentation) {
+    if (m_current == MmSegmentation && m_pending_color_shortcut_tens > 0) {
         GLGizmoMmuSegmentation* mmu_seg = dynamic_cast<GLGizmoMmuSegmentation*>(get_current());
-        mmu_seg->on_number_key_down(1);
+        if (mmu_seg != nullptr) {
+            mmu_seg->on_number_key_down(m_pending_color_shortcut_tens);
             m_parent.set_as_dirty();
         }
     }
+    m_pending_color_shortcut_tens = 0;
+}
 
 void GLGizmosManager::update_after_undo_redo(const UndoRedo::Snapshot& snapshot)
 {

src/slic3r/GUI/Gizmos/GLGizmosManager.hpp

@@ -144,6 +144,7 @@ private:
 
     //When there are more than 9 colors, shortcut key coloring
     wxTimer m_timer_set_color;
+    int m_pending_color_shortcut_tens = 0;
     void on_set_color_timer(wxTimerEvent& evt);
 
     // key MENU_ICON_NAME, value = ImtextureID

src/slic3r/GUI/MainFrame.cpp

@@ -2221,6 +2221,9 @@ bool MainFrame::get_enable_slice_status()
         }
     }
 
+    if (enable && m_plater->sidebar().has_broken_mixed_filament())
+        enable = false;
+
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": m_slice_select %1%, enable= %2% ")%m_slice_select %enable;
     return enable;
 }

src/slic3r/GUI/MixedFilamentColorMapPanel.cpp

@@ -0,0 +1,810 @@
+// MixedFilamentColorMapPanel.cpp
+// Extracted verbatim from FullSpectrum Plater.cpp:3087-3781 (Task 17).
+
+#include "MixedFilamentColorMapPanel.hpp"
+
+#include "libslic3r/filament_mixer.h"
+
+#include <wx/dcbuffer.h>
+#include <wx/event.h>
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+#include <limits>
+#include <numeric>
+#include <vector>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// Anonymous-namespace helpers — free functions used only by this widget.
+// Copied verbatim from FullSpectrum Plater.cpp:2443-2640.
+// ---------------------------------------------------------------------------
+namespace {
+
+wxColour blend_multi_filament_mixer(const std::vector<wxColour> &colors, const std::vector<double> &weights)
+{
+    if (colors.empty() || weights.empty())
+        return wxColour("#26A69A");
+
+    unsigned char out_r = 0;
+    unsigned char out_g = 0;
+    unsigned char out_b = 0;
+    double accumulated_weight = 0.0;
+    bool has_color = false;
+
+    for (size_t i = 0; i < colors.size() && i < weights.size(); ++i) {
+        const double weight = std::max(0.0, weights[i]);
+        if (weight <= 0.0)
+            continue;
+
+        const wxColour safe = colors[i].IsOk() ? colors[i] : wxColour("#26A69A");
+        const unsigned char r = static_cast<unsigned char>(safe.Red());
+        const unsigned char g = static_cast<unsigned char>(safe.Green());
+        const unsigned char b = static_cast<unsigned char>(safe.Blue());
+
+        if (!has_color) {
+            out_r = r;
+            out_g = g;
+            out_b = b;
+            accumulated_weight = weight;
+            has_color = true;
+            continue;
+        }
+
+        const double new_total = accumulated_weight + weight;
+        if (new_total <= 0.0)
+            continue;
+        const float t = float(weight / new_total);
+        ::Slic3r::filament_mixer_lerp(out_r, out_g, out_b, r, g, b, t, &out_r, &out_g, &out_b);
+        accumulated_weight = new_total;
+    }
+
+    if (!has_color)
+        return wxColour("#26A69A");
+
+    return wxColour(out_r, out_g, out_b);
+}
+
+std::vector<int> normalize_color_match_weights(const std::vector<int> &weights, size_t count)
+{
+    std::vector<int> out = weights;
+    if (out.size() != count)
+        out.assign(count, count > 0 ? int(100 / int(count)) : 0);
+
+    int sum = 0;
+    for (int &value : out) {
+        value = std::max(0, value);
+        sum += value;
+    }
+    if (sum <= 0 && count > 0) {
+        out.assign(count, 0);
+        out[0] = 100;
+        return out;
+    }
+
+    std::vector<double> remainders(count, 0.0);
+    int assigned = 0;
+    for (size_t idx = 0; idx < count; ++idx) {
+        const double exact = 100.0 * double(out[idx]) / double(sum);
+        out[idx]           = int(std::floor(exact));
+        remainders[idx]    = exact - double(out[idx]);
+        assigned          += out[idx];
+    }
+
+    int missing = std::max(0, 100 - assigned);
+    while (missing > 0) {
+        size_t best_idx       = 0;
+        double best_remainder = -1.0;
+        for (size_t idx = 0; idx < remainders.size(); ++idx) {
+            if (remainders[idx] > best_remainder) {
+                best_remainder = remainders[idx];
+                best_idx       = idx;
+            }
+        }
+        ++out[best_idx];
+        remainders[best_idx] = 0.0;
+        --missing;
+    }
+
+    return out;
+}
+
+bool color_match_raw_weights_within_range(const std::vector<double> &weights, int min_component_percent)
+{
+    if (min_component_percent <= 0)
+        return true;
+
+    const double min_allowed = double(std::clamp(min_component_percent, 0, 50));
+    int active_components = 0;
+    for (const double weight : weights) {
+        if (weight <= 1e-4)
+            continue;
+        ++active_components;
+        if (weight * 100.0 + 1e-6 < min_allowed)
+            return false;
+    }
+    return active_components >= 2;
+}
+
+} // anonymous namespace
+
+// ===========================================================================
+// MixedFilamentColorMapPanel — implementation
+// Verbatim from FullSpectrum Plater.cpp:3087-3781.
+// ===========================================================================
+
+MixedFilamentColorMapPanel::MixedFilamentColorMapPanel(wxWindow                        *parent,
+                                                       const std::vector<unsigned int> &filament_ids,
+                                                       const std::vector<wxColour>     &palette,
+                                                       const std::vector<int>          &initial_weights,
+                                                       const wxSize                    &min_size)
+    : wxPanel(parent, wxID_ANY, wxDefaultPosition, min_size, wxBORDER_SIMPLE)
+{
+    SetBackgroundStyle(wxBG_STYLE_PAINT);
+    SetMinSize(min_size);
+    m_render_timer.SetOwner(this);
+
+    m_colors.reserve(filament_ids.size());
+    for (const unsigned int filament_id : filament_ids) {
+        if (filament_id >= 1 && filament_id <= palette.size())
+            m_colors.emplace_back(palette[filament_id - 1]);
+        else
+            m_colors.emplace_back(wxColour("#26A69A"));
+    }
+    if (m_colors.empty())
+        m_colors.emplace_back(wxColour("#26A69A"));
+
+    set_normalized_weights(initial_weights, false);
+
+    Bind(wxEVT_PAINT,              &MixedFilamentColorMapPanel::on_paint,        this);
+    Bind(wxEVT_LEFT_DOWN,          &MixedFilamentColorMapPanel::on_left_down,    this);
+    Bind(wxEVT_LEFT_UP,            &MixedFilamentColorMapPanel::on_left_up,      this);
+    Bind(wxEVT_MOTION,             &MixedFilamentColorMapPanel::on_mouse_move,   this);
+    Bind(wxEVT_MOUSE_CAPTURE_LOST, &MixedFilamentColorMapPanel::on_capture_lost, this);
+    Bind(wxEVT_SIZE,               &MixedFilamentColorMapPanel::on_size,         this);
+    Bind(wxEVT_TIMER,              &MixedFilamentColorMapPanel::on_render_timer, this, m_render_timer.GetId());
+}
+
+MixedFilamentColorMapPanel::~MixedFilamentColorMapPanel()
+{
+    if (HasCapture())
+        ReleaseMouse();
+    if (m_render_timer.IsRunning())
+        m_render_timer.Stop();
+}
+
+std::vector<int> MixedFilamentColorMapPanel::normalized_weights() const
+{
+    return m_weights;
+}
+
+wxColour MixedFilamentColorMapPanel::selected_color() const
+{
+    std::vector<double> weights;
+    weights.reserve(m_weights.size());
+    for (const int weight : m_weights)
+        weights.emplace_back(double(std::max(0, weight)));
+    return blend_multi_filament_mixer(m_colors, weights);
+}
+
+void MixedFilamentColorMapPanel::set_normalized_weights(const std::vector<int> &weights, bool notify)
+{
+    m_weights = normalize_color_match_weights(weights, m_colors.size());
+    initialize_cursor_from_weights();
+    Refresh();
+    if (notify)
+        emit_changed();
+}
+
+void MixedFilamentColorMapPanel::set_min_component_percent(int min_component_percent)
+{
+    const int clamped = std::clamp(min_component_percent, 0, 50);
+    if (m_min_component_percent == clamped)
+        return;
+    m_min_component_percent = clamped;
+    invalidate_cached_bitmap();
+    Refresh();
+}
+
+// ---------------------------------------------------------------------------
+// Private: geometry helpers
+// ---------------------------------------------------------------------------
+
+MixedFilamentColorMapPanel::GeometryMode MixedFilamentColorMapPanel::geometry_mode() const
+{
+    if (m_colors.size() <= 1)
+        return GeometryMode::Point;
+    if (m_colors.size() == 2)
+        return GeometryMode::Line;
+    if (m_colors.size() == 3)
+        return GeometryMode::Triangle;
+    if (m_colors.size() == 4)
+        return GeometryMode::TriangleWithCenter;
+    return GeometryMode::Radial;
+}
+
+wxRect MixedFilamentColorMapPanel::canvas_rect() const
+{
+    const wxSize size = GetClientSize();
+    return wxRect(0, 0, std::max(1, size.GetWidth()), std::max(1, size.GetHeight()));
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::make_vec(double x, double y)
+{
+    return Vec2 { x, y };
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::add_vec(const Vec2 &lhs, const Vec2 &rhs)
+{
+    return Vec2 { lhs.x + rhs.x, lhs.y + rhs.y };
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::sub_vec(const Vec2 &lhs, const Vec2 &rhs)
+{
+    return Vec2 { lhs.x - rhs.x, lhs.y - rhs.y };
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::scale_vec(const Vec2 &value, double factor)
+{
+    return Vec2 { value.x * factor, value.y * factor };
+}
+
+double MixedFilamentColorMapPanel::dot_vec(const Vec2 &lhs, const Vec2 &rhs)
+{
+    return lhs.x * rhs.x + lhs.y * rhs.y;
+}
+
+double MixedFilamentColorMapPanel::length_sq(const Vec2 &value)
+{
+    return dot_vec(value, value);
+}
+
+double MixedFilamentColorMapPanel::dist_sq(const Vec2 &lhs, const Vec2 &rhs)
+{
+    return length_sq(sub_vec(lhs, rhs));
+}
+
+std::array<MixedFilamentColorMapPanel::Vec2, 3> MixedFilamentColorMapPanel::simplex_vertices() const
+{
+    return { make_vec(0.50, 0.05), make_vec(0.08, 0.94), make_vec(0.92, 0.94) };
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::simplex_center() const
+{
+    const auto vertices = simplex_vertices();
+    return make_vec((vertices[0].x + vertices[1].x + vertices[2].x) / 3.0,
+                    (vertices[0].y + vertices[1].y + vertices[2].y) / 3.0);
+}
+
+std::vector<MixedFilamentColorMapPanel::AnchorPoint> MixedFilamentColorMapPanel::radial_anchor_points() const
+{
+    std::vector<AnchorPoint> anchors;
+    const size_t count = m_colors.size();
+    anchors.reserve(count);
+    if (count == 0)
+        return anchors;
+    if (count == 1) {
+        anchors.emplace_back(AnchorPoint { 0.5, 0.5 });
+        return anchors;
+    }
+    if (count == 2) {
+        anchors.emplace_back(AnchorPoint { 0.0, 0.5 });
+        anchors.emplace_back(AnchorPoint { 1.0, 0.5 });
+        return anchors;
+    }
+    if (count == 3) {
+        anchors.emplace_back(AnchorPoint { 0.0, 0.5 });
+        anchors.emplace_back(AnchorPoint { 1.0, 0.0 });
+        anchors.emplace_back(AnchorPoint { 1.0, 1.0 });
+        return anchors;
+    }
+    if (count == 4) {
+        anchors.emplace_back(AnchorPoint { 0.0, 0.0 });
+        anchors.emplace_back(AnchorPoint { 1.0, 0.0 });
+        anchors.emplace_back(AnchorPoint { 1.0, 1.0 });
+        anchors.emplace_back(AnchorPoint { 0.0, 1.0 });
+        return anchors;
+    }
+
+    constexpr double k_pi = 3.14159265358979323846;
+    const double center_x = 0.5;
+    const double center_y = 0.5;
+    const double radius = 0.45;
+    for (size_t idx = 0; idx < count; ++idx) {
+        const double angle = (2.0 * k_pi * double(idx)) / double(count);
+        anchors.emplace_back(AnchorPoint { center_x + radius * std::cos(angle), center_y + radius * std::sin(angle) });
+    }
+    return anchors;
+}
+
+std::vector<MixedFilamentColorMapPanel::AnchorPoint> MixedFilamentColorMapPanel::anchor_points() const
+{
+    std::vector<AnchorPoint> anchors;
+    switch (geometry_mode()) {
+    case GeometryMode::Point:
+        anchors.emplace_back(AnchorPoint { 0.5, 0.5 });
+        break;
+    case GeometryMode::Line:
+        anchors.emplace_back(AnchorPoint { 0.06, 0.5 });
+        anchors.emplace_back(AnchorPoint { 0.94, 0.5 });
+        break;
+    case GeometryMode::Triangle: {
+        const auto vertices = simplex_vertices();
+        for (const Vec2 &vertex : vertices)
+            anchors.emplace_back(AnchorPoint { vertex.x, vertex.y });
+        break;
+    }
+    case GeometryMode::TriangleWithCenter: {
+        const auto vertices = simplex_vertices();
+        for (const Vec2 &vertex : vertices)
+            anchors.emplace_back(AnchorPoint { vertex.x, vertex.y });
+        const Vec2 center = simplex_center();
+        anchors.emplace_back(AnchorPoint { center.x, center.y });
+        break;
+    }
+    case GeometryMode::Radial:
+        anchors = radial_anchor_points();
+        break;
+    }
+    return anchors;
+}
+
+std::array<double, 3> MixedFilamentColorMapPanel::triangle_barycentric(const Vec2 &point, const std::array<Vec2, 3> &triangle)
+{
+    const Vec2 &a = triangle[0];
+    const Vec2 &b = triangle[1];
+    const Vec2 &c = triangle[2];
+    const double denom = ((b.y - c.y) * (a.x - c.x) + (c.x - b.x) * (a.y - c.y));
+    if (std::abs(denom) <= 1e-9)
+        return { 1.0, 0.0, 0.0 };
+    const double w0 = ((b.y - c.y) * (point.x - c.x) + (c.x - b.x) * (point.y - c.y)) / denom;
+    const double w1 = ((c.y - a.y) * (point.x - c.x) + (a.x - c.x) * (point.y - c.y)) / denom;
+    const double w2 = 1.0 - w0 - w1;
+    return { w0, w1, w2 };
+}
+
+bool MixedFilamentColorMapPanel::point_in_triangle(const Vec2 &point, const std::array<Vec2, 3> &triangle)
+{
+    const auto barycentric = triangle_barycentric(point, triangle);
+    constexpr double eps = 1e-6;
+    return barycentric[0] >= -eps && barycentric[1] >= -eps && barycentric[2] >= -eps;
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::closest_point_on_segment(const Vec2 &point, const Vec2 &start, const Vec2 &end)
+{
+    const Vec2 edge = sub_vec(end, start);
+    const double edge_len_sq = length_sq(edge);
+    if (edge_len_sq <= 1e-9)
+        return start;
+    const double t = std::clamp(dot_vec(sub_vec(point, start), edge) / edge_len_sq, 0.0, 1.0);
+    return add_vec(start, scale_vec(edge, t));
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::closest_point_on_triangle(const Vec2 &point, const std::array<Vec2, 3> &triangle)
+{
+    if (point_in_triangle(point, triangle))
+        return point;
+
+    Vec2 best = triangle[0];
+    double best_dist = std::numeric_limits<double>::max();
+    for (int edge_idx = 0; edge_idx < 3; ++edge_idx) {
+        const Vec2 candidate = closest_point_on_segment(point, triangle[edge_idx], triangle[(edge_idx + 1) % 3]);
+        const double candidate_dist = dist_sq(point, candidate);
+        if (candidate_dist < best_dist) {
+            best_dist = candidate_dist;
+            best = candidate;
+        }
+    }
+    return best;
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::normalized_point_from_mouse(const wxMouseEvent &evt) const
+{
+    const wxRect rect = canvas_rect();
+    const int width = std::max(1, rect.GetWidth() - 1);
+    const int height = std::max(1, rect.GetHeight() - 1);
+    return make_vec(
+        std::clamp(double(evt.GetX() - rect.GetLeft()) / double(width), 0.0, 1.0),
+        std::clamp(double(evt.GetY() - rect.GetTop()) / double(height), 0.0, 1.0));
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::clamp_point_to_geometry(const Vec2 &point) const
+{
+    switch (geometry_mode()) {
+    case GeometryMode::Point:
+        return make_vec(0.5, 0.5);
+    case GeometryMode::Line:
+        return make_vec(std::clamp(point.x, 0.0, 1.0), 0.5);
+    case GeometryMode::Triangle:
+    case GeometryMode::TriangleWithCenter:
+        return closest_point_on_triangle(point, simplex_vertices());
+    case GeometryMode::Radial:
+        return make_vec(std::clamp(point.x, 0.0, 1.0), std::clamp(point.y, 0.0, 1.0));
+    }
+    return point;
+}
+
+std::vector<double> MixedFilamentColorMapPanel::simplex_weights_from_pos(const Vec2 &point) const
+{
+    const auto triangle = simplex_vertices();
+    const Vec2 clamped = closest_point_on_triangle(point, triangle);
+    const auto barycentric = triangle_barycentric(clamped, triangle);
+
+    if (geometry_mode() == GeometryMode::Triangle)
+        return { std::max(0.0, barycentric[0]), std::max(0.0, barycentric[1]), std::max(0.0, barycentric[2]) };
+
+    const double shared = std::max(0.0, std::min({ barycentric[0], barycentric[1], barycentric[2] }));
+    return {
+        std::max(0.0, barycentric[0] - shared),
+        std::max(0.0, barycentric[1] - shared),
+        std::max(0.0, barycentric[2] - shared),
+        std::max(0.0, shared * 3.0)
+    };
+}
+
+MixedFilamentColorMapPanel::Vec2 MixedFilamentColorMapPanel::triangle_point_from_weights() const
+{
+    const auto vertices = simplex_vertices();
+    double total = 0.0;
+    for (size_t idx = 0; idx < 3 && idx < m_weights.size(); ++idx)
+        total += std::max(0, m_weights[idx]);
+    if (total <= 0.0)
+        return simplex_center();
+
+    Vec2 out = make_vec(0.0, 0.0);
+    for (size_t idx = 0; idx < 3 && idx < m_weights.size(); ++idx) {
+        const double weight = double(std::max(0, m_weights[idx])) / total;
+        out = add_vec(out, scale_vec(vertices[idx], weight));
+    }
+    return out;
+}
+
+void MixedFilamentColorMapPanel::initialize_cursor_from_grid_search()
+{
+    double best_x = 0.5;
+    double best_y = 0.5;
+    double best_error = std::numeric_limits<double>::max();
+    constexpr int grid = 96;
+    for (int y_idx = 0; y_idx <= grid; ++y_idx) {
+        for (int x_idx = 0; x_idx <= grid; ++x_idx) {
+            const Vec2 point = clamp_point_to_geometry(make_vec(double(x_idx) / double(grid), double(y_idx) / double(grid)));
+            const std::vector<int> probe = normalized_weights_from_pos(point.x, point.y);
+            if (probe.size() != m_weights.size())
+                continue;
+            double error = 0.0;
+            for (size_t idx = 0; idx < probe.size(); ++idx) {
+                const double delta = double(probe[idx] - m_weights[idx]);
+                error += delta * delta;
+            }
+            if (error < best_error) {
+                best_error = error;
+                best_x = point.x;
+                best_y = point.y;
+            }
+        }
+    }
+    m_cursor_x = best_x;
+    m_cursor_y = best_y;
+    m_weights = normalized_weights_from_pos(m_cursor_x, m_cursor_y);
+}
+
+std::vector<double> MixedFilamentColorMapPanel::raw_weights_from_pos(double normalized_x, double normalized_y) const
+{
+    switch (geometry_mode()) {
+    case GeometryMode::Point:
+        return { 1.0 };
+    case GeometryMode::Line: {
+        const double t = std::clamp(normalized_x, 0.0, 1.0);
+        return { 1.0 - t, t };
+    }
+    case GeometryMode::Triangle:
+    case GeometryMode::TriangleWithCenter:
+        return simplex_weights_from_pos(make_vec(normalized_x, normalized_y));
+    case GeometryMode::Radial:
+        break;
+    }
+
+    const std::vector<AnchorPoint> anchors = radial_anchor_points();
+    std::vector<double> out(anchors.size(), 0.0);
+    if (anchors.empty())
+        return out;
+
+    constexpr double eps = 1e-8;
+    size_t exact_idx = size_t(-1);
+    for (size_t idx = 0; idx < anchors.size(); ++idx) {
+        const double dx = normalized_x - anchors[idx].x;
+        const double dy = normalized_y - anchors[idx].y;
+        const double d2 = dx * dx + dy * dy;
+        if (d2 <= eps) {
+            exact_idx = idx;
+            break;
+        }
+        out[idx] = 1.0 / std::max(1e-6, d2);
+    }
+    if (exact_idx != size_t(-1)) {
+        std::fill(out.begin(), out.end(), 0.0);
+        out[exact_idx] = 1.0;
+        return out;
+    }
+
+    double sum = 0.0;
+    for (const double value : out)
+        sum += value;
+    if (sum <= 0.0) {
+        out.assign(out.size(), 0.0);
+        out[0] = 1.0;
+        return out;
+    }
+    for (double &value : out)
+        value /= sum;
+    return out;
+}
+
+std::vector<int> MixedFilamentColorMapPanel::normalized_weights_from_pos(double normalized_x, double normalized_y) const
+{
+    std::vector<int> raw_weights;
+    const std::vector<double> raw = raw_weights_from_pos(normalized_x, normalized_y);
+    raw_weights.reserve(raw.size());
+    for (const double value : raw)
+        raw_weights.emplace_back(std::max(0, int(std::lround(value * 100.0))));
+    return normalize_color_match_weights(raw_weights, raw.size());
+}
+
+void MixedFilamentColorMapPanel::initialize_cursor_from_weights()
+{
+    if (m_weights.empty()) {
+        m_cursor_x = 0.5;
+        m_cursor_y = 0.5;
+        return;
+    }
+
+    switch (geometry_mode()) {
+    case GeometryMode::Point:
+        m_cursor_x = 0.5;
+        m_cursor_y = 0.5;
+        break;
+    case GeometryMode::Line: {
+        const int total = std::accumulate(m_weights.begin(), m_weights.end(), 0);
+        const double t = total > 0 && m_weights.size() >= 2 ? double(std::max(0, m_weights[1])) / double(total) : 0.5;
+        m_cursor_x = std::clamp(t, 0.0, 1.0);
+        m_cursor_y = 0.5;
+        m_weights = normalized_weights_from_pos(m_cursor_x, m_cursor_y);
+        break;
+    }
+    case GeometryMode::Triangle: {
+        const Vec2 point = triangle_point_from_weights();
+        m_cursor_x = point.x;
+        m_cursor_y = point.y;
+        m_weights = normalized_weights_from_pos(m_cursor_x, m_cursor_y);
+        break;
+    }
+    case GeometryMode::TriangleWithCenter:
+    case GeometryMode::Radial:
+        initialize_cursor_from_grid_search();
+        break;
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Private: interaction + rendering
+// ---------------------------------------------------------------------------
+
+void MixedFilamentColorMapPanel::emit_changed()
+{
+    wxCommandEvent evt(wxEVT_SLIDER, GetId());
+    evt.SetEventObject(this);
+    ProcessWindowEvent(evt);
+}
+
+void MixedFilamentColorMapPanel::update_from_mouse(const wxMouseEvent &evt, bool notify)
+{
+    const Vec2 point = clamp_point_to_geometry(normalized_point_from_mouse(evt));
+    m_cursor_x = point.x;
+    m_cursor_y = point.y;
+    m_weights = normalized_weights_from_pos(m_cursor_x, m_cursor_y);
+    Refresh();
+    if (notify)
+        emit_changed();
+}
+
+wxColour MixedFilamentColorMapPanel::canvas_background_color() const
+{
+    return GetBackgroundColour().IsOk() ? GetBackgroundColour() : wxColour(245, 245, 245);
+}
+
+bool MixedFilamentColorMapPanel::cached_bitmap_matches(const wxSize &size, const wxColour &background) const
+{
+    return m_cached_bitmap.IsOk() && m_cached_bitmap_size == size && m_cached_background == background;
+}
+
+void MixedFilamentColorMapPanel::schedule_cached_bitmap_render()
+{
+    if (!m_render_timer.IsRunning())
+        m_render_timer.StartOnce(80);
+}
+
+void MixedFilamentColorMapPanel::invalidate_cached_bitmap()
+{
+    m_cached_bitmap = wxBitmap();
+    m_cached_bitmap_size = wxSize();
+    m_cached_background = wxColour();
+}
+
+void MixedFilamentColorMapPanel::render_cached_bitmap(const wxSize &size, const wxColour &background)
+{
+    const int width = size.GetWidth();
+    const int height = size.GetHeight();
+    if (width <= 0 || height <= 0)
+        return;
+
+    wxImage image(width, height);
+    unsigned char *data = image.GetData();
+    if (data != nullptr) {
+        for (int y = 0; y < height; ++y) {
+            const double normalized_y = (height > 1) ? double(y) / double(height - 1) : 0.5;
+            for (int x = 0; x < width; ++x) {
+                const double normalized_x = (width > 1) ? double(x) / double(width - 1) : 0.5;
+                const int data_idx = (y * width + x) * 3;
+                bool paint_pixel = true;
+                if (geometry_mode() == GeometryMode::Triangle || geometry_mode() == GeometryMode::TriangleWithCenter)
+                    paint_pixel = point_in_triangle(make_vec(normalized_x, normalized_y), simplex_vertices());
+
+                const std::vector<double> raw_weights = raw_weights_from_pos(normalized_x, normalized_y);
+                wxColour color = paint_pixel ? blend_multi_filament_mixer(m_colors, raw_weights) : background;
+                if (paint_pixel && m_min_component_percent > 0 &&
+                    !color_match_raw_weights_within_range(raw_weights, m_min_component_percent)) {
+                    const bool stripe = (((x + y) / 8) % 2) == 0;
+                    const double factor = stripe ? 0.12 : 0.38;
+                    color = wxColour(
+                        static_cast<unsigned char>(std::clamp(int(std::lround(double(color.Red()) * factor)), 0, 255)),
+                        static_cast<unsigned char>(std::clamp(int(std::lround(double(color.Green()) * factor)), 0, 255)),
+                        static_cast<unsigned char>(std::clamp(int(std::lround(double(color.Blue()) * factor)), 0, 255)));
+                }
+                data[data_idx + 0] = color.Red();
+                data[data_idx + 1] = color.Green();
+                data[data_idx + 2] = color.Blue();
+            }
+        }
+    }
+
+    m_cached_bitmap = wxBitmap(image);
+    m_cached_bitmap_size = size;
+    m_cached_background = background;
+}
+
+void MixedFilamentColorMapPanel::draw_cached_bitmap(wxAutoBufferedPaintDC &dc, const wxRect &rect)
+{
+    if (!m_cached_bitmap.IsOk())
+        return;
+
+    if (m_cached_bitmap_size == rect.GetSize()) {
+        dc.DrawBitmap(m_cached_bitmap, rect.GetLeft(), rect.GetTop(), false);
+        return;
+    }
+
+    wxMemoryDC memdc;
+    memdc.SelectObject(m_cached_bitmap);
+    dc.StretchBlit(rect.GetLeft(), rect.GetTop(), rect.GetWidth(), rect.GetHeight(),
+                   &memdc, 0, 0, m_cached_bitmap_size.GetWidth(), m_cached_bitmap_size.GetHeight());
+    memdc.SelectObject(wxNullBitmap);
+}
+
+// ---------------------------------------------------------------------------
+// Event handlers
+// ---------------------------------------------------------------------------
+
+void MixedFilamentColorMapPanel::on_paint(wxPaintEvent &)
+{
+    wxAutoBufferedPaintDC dc(this);
+    dc.SetBackground(wxBrush(GetBackgroundColour()));
+    dc.Clear();
+
+    const wxRect rect = canvas_rect();
+    const int width = rect.GetWidth();
+    const int height = rect.GetHeight();
+    if (width <= 0 || height <= 0)
+        return;
+
+    const wxColour background = canvas_background_color();
+    if (!cached_bitmap_matches(rect.GetSize(), background)) {
+        if (!m_cached_bitmap.IsOk())
+            render_cached_bitmap(rect.GetSize(), background);
+        else
+            schedule_cached_bitmap_render();
+    }
+    draw_cached_bitmap(dc, rect);
+
+    if (geometry_mode() == GeometryMode::Triangle || geometry_mode() == GeometryMode::TriangleWithCenter) {
+        const auto triangle = simplex_vertices();
+        wxPoint points[3] = {
+            wxPoint(rect.GetLeft() + int(std::lround(triangle[0].x * double(std::max(1, width - 1)))),
+                    rect.GetTop()  + int(std::lround(triangle[0].y * double(std::max(1, height - 1))))),
+            wxPoint(rect.GetLeft() + int(std::lround(triangle[1].x * double(std::max(1, width - 1)))),
+                    rect.GetTop()  + int(std::lround(triangle[1].y * double(std::max(1, height - 1))))),
+            wxPoint(rect.GetLeft() + int(std::lround(triangle[2].x * double(std::max(1, width - 1)))),
+                    rect.GetTop()  + int(std::lround(triangle[2].y * double(std::max(1, height - 1)))))
+        };
+        dc.SetPen(wxPen(wxColour(160, 160, 160), 1));
+        dc.SetBrush(*wxTRANSPARENT_BRUSH);
+        dc.DrawPolygon(3, points);
+        if (geometry_mode() == GeometryMode::TriangleWithCenter) {
+            const Vec2 center = simplex_center();
+            const wxPoint center_pt(rect.GetLeft() + int(std::lround(center.x * double(std::max(1, width - 1)))),
+                                    rect.GetTop()  + int(std::lround(center.y * double(std::max(1, height - 1)))));
+            dc.SetPen(wxPen(wxColour(180, 180, 180), 1, wxPENSTYLE_DOT));
+            for (const wxPoint &vertex : points)
+                dc.DrawLine(center_pt, vertex);
+        }
+    } else {
+        dc.SetPen(wxPen(wxColour(160, 160, 160), 1));
+        dc.SetBrush(*wxTRANSPARENT_BRUSH);
+        dc.DrawRectangle(rect);
+    }
+
+    dc.SetPen(wxPen(wxColour(160, 160, 160), 1));
+    dc.SetBrush(*wxTRANSPARENT_BRUSH);
+
+    const auto anchors = anchor_points();
+    for (size_t idx = 0; idx < anchors.size() && idx < m_colors.size(); ++idx) {
+        const int anchor_x = rect.GetLeft() + int(std::lround(anchors[idx].x * double(std::max(1, width - 1))));
+        const int anchor_y = rect.GetTop() + int(std::lround(anchors[idx].y * double(std::max(1, height - 1))));
+        dc.SetPen(wxPen(wxColour(30, 30, 30), 1));
+        dc.SetBrush(wxBrush(m_colors[idx]));
+        dc.DrawCircle(wxPoint(anchor_x, anchor_y), FromDIP(4));
+    }
+
+    const int cursor_x = rect.GetLeft() + int(std::lround(m_cursor_x * double(std::max(1, width - 1))));
+    const int cursor_y = rect.GetTop() + int(std::lround(m_cursor_y * double(std::max(1, height - 1))));
+    dc.SetPen(wxPen(wxColour(255, 255, 255), 3));
+    dc.SetBrush(*wxTRANSPARENT_BRUSH);
+    dc.DrawCircle(wxPoint(cursor_x, cursor_y), FromDIP(7));
+    dc.SetPen(wxPen(wxColour(30, 30, 30), 1));
+    dc.DrawCircle(wxPoint(cursor_x, cursor_y), FromDIP(7));
+}
+
+void MixedFilamentColorMapPanel::on_left_down(wxMouseEvent &evt)
+{
+    if (!HasCapture())
+        CaptureMouse();
+    m_dragging = true;
+    update_from_mouse(evt, true);
+}
+
+void MixedFilamentColorMapPanel::on_left_up(wxMouseEvent &evt)
+{
+    if (m_dragging)
+        update_from_mouse(evt, true);
+    m_dragging = false;
+    if (HasCapture())
+        ReleaseMouse();
+}
+
+void MixedFilamentColorMapPanel::on_mouse_move(wxMouseEvent &evt)
+{
+    if (m_dragging && evt.LeftIsDown())
+        update_from_mouse(evt, true);
+}
+
+void MixedFilamentColorMapPanel::on_capture_lost(wxMouseCaptureLostEvent &)
+{
+    m_dragging = false;
+}
+
+void MixedFilamentColorMapPanel::on_size(wxSizeEvent &evt)
+{
+    if (m_cached_bitmap.IsOk())
+        schedule_cached_bitmap_render();
+    Refresh(false);
+    evt.Skip();
+}
+
+void MixedFilamentColorMapPanel::on_render_timer(wxTimerEvent &)
+{
+    const wxRect rect = canvas_rect();
+    render_cached_bitmap(rect.GetSize(), canvas_background_color());
+    Refresh(false);
+}
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedFilamentColorMapPanel.hpp

@@ -0,0 +1,138 @@
+#pragma once
+#include <wx/panel.h>
+#include <wx/timer.h>
+#include <wx/bitmap.h>
+#include <wx/colour.h>
+#include <vector>
+#include <array>
+#include <functional>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// MixedFilamentColorMapPanel
+//
+// Interactive colour-map widget that lets the user pick a multi-filament
+// blend by dragging a cursor across a geometry-specific gradient map.
+//
+// Extracted verbatim from FullSpectrum Plater.cpp:3087-3781 (Task 17).
+// ---------------------------------------------------------------------------
+class MixedFilamentColorMapPanel : public wxPanel
+{
+public:
+    MixedFilamentColorMapPanel(wxWindow                        *parent,
+                               const std::vector<unsigned int> &filament_ids,
+                               const std::vector<wxColour>     &palette,
+                               const std::vector<int>          &initial_weights,
+                               const wxSize                    &min_size);
+
+    ~MixedFilamentColorMapPanel() override;
+
+    // Returns the current normalised per-filament weights (sum == 100).
+    std::vector<int> normalized_weights() const;
+
+    // Returns the blended wxColour that corresponds to the current cursor position.
+    wxColour selected_color() const;
+
+    // Programmatically update weights; notify==true fires wxEVT_SLIDER.
+    void set_normalized_weights(const std::vector<int> &weights, bool notify);
+
+    // Minimum per-component percentage below which the region is dimmed/striped.
+    void set_min_component_percent(int min_component_percent);
+
+private:
+    // -----------------------------------------------------------------------
+    // Private nested types (verbatim from FullSpectrum Plater.cpp:3160-3180)
+    // -----------------------------------------------------------------------
+    enum class GeometryMode {
+        Point,
+        Line,
+        Triangle,
+        TriangleWithCenter,
+        Radial
+    };
+
+    struct AnchorPoint {
+        double x { 0.5 };
+        double y { 0.5 };
+    };
+
+    struct Vec2 {
+        double x { 0.0 };
+        double y { 0.0 };
+    };
+
+    // -----------------------------------------------------------------------
+    // Geometry helpers (all inlined in .cpp)
+    // -----------------------------------------------------------------------
+    GeometryMode geometry_mode() const;
+    wxRect       canvas_rect() const;
+
+    static Vec2   make_vec(double x, double y);
+    static Vec2   add_vec(const Vec2 &lhs, const Vec2 &rhs);
+    static Vec2   sub_vec(const Vec2 &lhs, const Vec2 &rhs);
+    static Vec2   scale_vec(const Vec2 &value, double factor);
+    static double dot_vec(const Vec2 &lhs, const Vec2 &rhs);
+    static double length_sq(const Vec2 &value);
+    static double dist_sq(const Vec2 &lhs, const Vec2 &rhs);
+
+    std::array<Vec2, 3>      simplex_vertices() const;
+    Vec2                     simplex_center() const;
+    std::vector<AnchorPoint> radial_anchor_points() const;
+    std::vector<AnchorPoint> anchor_points() const;
+
+    static std::array<double, 3> triangle_barycentric(const Vec2 &point, const std::array<Vec2, 3> &triangle);
+    static bool                  point_in_triangle(const Vec2 &point, const std::array<Vec2, 3> &triangle);
+    static Vec2                  closest_point_on_segment(const Vec2 &point, const Vec2 &start, const Vec2 &end);
+    static Vec2                  closest_point_on_triangle(const Vec2 &point, const std::array<Vec2, 3> &triangle);
+
+    Vec2 normalized_point_from_mouse(const wxMouseEvent &evt) const;
+    Vec2 clamp_point_to_geometry(const Vec2 &point) const;
+
+    std::vector<double> simplex_weights_from_pos(const Vec2 &point) const;
+    Vec2                triangle_point_from_weights() const;
+    void                initialize_cursor_from_grid_search();
+    std::vector<double> raw_weights_from_pos(double normalized_x, double normalized_y) const;
+    std::vector<int>    normalized_weights_from_pos(double normalized_x, double normalized_y) const;
+    void                initialize_cursor_from_weights();
+
+    // -----------------------------------------------------------------------
+    // Rendering helpers
+    // -----------------------------------------------------------------------
+    void emit_changed();
+    void update_from_mouse(const wxMouseEvent &evt, bool notify);
+
+    wxColour canvas_background_color() const;
+    bool     cached_bitmap_matches(const wxSize &size, const wxColour &background) const;
+    void     schedule_cached_bitmap_render();
+    void     invalidate_cached_bitmap();
+    void     render_cached_bitmap(const wxSize &size, const wxColour &background);
+    void     draw_cached_bitmap(wxAutoBufferedPaintDC &dc, const wxRect &rect);
+
+    // -----------------------------------------------------------------------
+    // wx event handlers
+    // -----------------------------------------------------------------------
+    void on_paint(wxPaintEvent &evt);
+    void on_left_down(wxMouseEvent &evt);
+    void on_left_up(wxMouseEvent &evt);
+    void on_mouse_move(wxMouseEvent &evt);
+    void on_capture_lost(wxMouseCaptureLostEvent &evt);
+    void on_size(wxSizeEvent &evt);
+    void on_render_timer(wxTimerEvent &evt);
+
+    // -----------------------------------------------------------------------
+    // Member variables (verbatim from FullSpectrum Plater.cpp:3761-3779)
+    // -----------------------------------------------------------------------
+    std::vector<wxColour> m_colors;
+    std::vector<int>      m_weights;
+    wxBitmap              m_cached_bitmap;
+    wxSize                m_cached_bitmap_size;
+    wxColour              m_cached_background;
+    wxTimer               m_render_timer;
+    int                   m_min_component_percent { 0 };
+    double                m_cursor_x { 0.5 };
+    double                m_cursor_y { 0.5 };
+    bool                  m_dragging { false };
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedFilamentColorMatchDialog.hpp

@@ -0,0 +1,143 @@
+#pragma once
+#include <wx/dialog.h>
+#include <wx/clrpicker.h>
+#include <wx/colour.h>
+#include <wx/gauge.h>
+#include <wx/scrolwin.h>
+#include <wx/slider.h>
+#include <wx/stattext.h>
+#include <wx/textctrl.h>
+#include <wx/timer.h>
+#include <wx/wrapsizer.h>
+#include <limits>
+#include <string>
+#include <vector>
+#include "GUI_Utils.hpp"
+#include "libslic3r/MixedFilament.hpp"
+
+namespace Slic3r { namespace GUI {
+
+class MixedFilamentColorMapPanel; // Task 17
+
+// ---------------------------------------------------------------------------
+// MixedColorMatchRecipeResult
+//
+// Verbatim from FullSpectrum Plater.cpp:230-242.
+// Holds the result of a brute-force C(N,2)/C(N,3)/C(N,4) ΔE₀₀ search.
+// ---------------------------------------------------------------------------
+struct MixedColorMatchRecipeResult
+{
+    bool         cancelled                  = false;
+    bool         valid                      = false;
+    unsigned int component_a                = 1;
+    unsigned int component_b                = 2;
+    int          mix_b_percent              = 50;
+    std::string  manual_pattern;
+    std::string  gradient_component_ids;
+    std::string  gradient_component_weights;
+    wxColour     preview_color              = wxColour("#26A69A");
+    double       delta_e                    = std::numeric_limits<double>::infinity();
+};
+
+// Free helper (was declared at Plater.cpp:244-246): launch dialog, return recipe.
+MixedColorMatchRecipeResult prompt_best_color_match_recipe(
+    wxWindow *parent,
+    const std::vector<std::string> &physical_colors,
+    const wxColour &initial_color);
+
+// Free helper (was declared at Plater.cpp:251):
+// build a MixedFilamentDisplayContext from a flat color vector.
+MixedFilamentDisplayContext build_mixed_filament_display_context(
+    const std::vector<std::string> &physical_colors);
+
+// Free helper (was declared in Plater.cpp anon namespace at 252):
+// map a recipe to a swatch colour using the display context.
+wxColour compute_color_match_recipe_display_color(
+    const MixedColorMatchRecipeResult &recipe,
+    const MixedFilamentDisplayContext &context);
+
+// Free helper (was declared at Plater.cpp:247): ΔE₀₀ between two wxColours.
+double color_delta_e00(const wxColour &lhs, const wxColour &rhs);
+
+// ---------------------------------------------------------------------------
+// MixedFilamentColorMatchDialog
+//
+// Extracted verbatim from FullSpectrum Plater.cpp:3782-4288.
+// The user types/picks an arbitrary target colour and a brute-force search
+// finds the C(N,2)/C(N,3)/C(N,4) recipe that minimises ΔE₀₀ to that target.
+// ---------------------------------------------------------------------------
+class MixedFilamentColorMatchDialog : public DPIDialog
+{
+public:
+    MixedFilamentColorMatchDialog(wxWindow *parent,
+                                  const std::vector<std::string> &physical_colors,
+                                  const wxColour &initial_color);
+
+    ~MixedFilamentColorMatchDialog() override;
+
+    // Kick off the initial background recipe search (called after ShowModal starts).
+    void begin_initial_recipe_load();
+
+    MixedColorMatchRecipeResult selected_recipe() const { return m_selected_recipe; }
+
+    void on_dpi_changed(const wxRect &suggested_rect) override;
+
+private:
+    // UI helpers
+    void update_range_label();
+    void rebuild_presets_ui();
+    void set_recipe_loading(bool loading, const wxString &message);
+    void sync_inputs_to_requested();
+    bool apply_requested_target(const wxColour &requested_target);
+    bool apply_hex_input(bool show_invalid_error);
+    void request_recipe_match(const wxColour &requested_target, bool debounce, const wxString &loading_message);
+    void refresh_selected_recipe();
+    void launch_recipe_match(size_t request_token, const wxColour &requested_target);
+    void update_dialog_state();
+
+    // Declared in the task spec's public API
+    void sync_recipe_preview(MixedColorMatchRecipeResult &recipe, const wxColour *requested_target = nullptr);
+    void handle_recipe_result(size_t request_token, const wxColour &requested_target, MixedColorMatchRecipeResult recipe);
+    void apply_preset(MixedColorMatchRecipeResult preset);
+
+    // Data
+    std::vector<std::string>                 m_physical_colors;
+    MixedFilamentDisplayContext              m_display_context;
+    std::vector<wxColour>                    m_palette;
+    std::vector<MixedColorMatchRecipeResult> m_presets;
+    MixedFilamentColorMapPanel              *m_color_map        = nullptr;
+
+    // Widgets
+    wxTextCtrl        *m_hex_input        = nullptr;
+    wxColourPickerCtrl *m_classic_picker  = nullptr;
+    wxSlider          *m_range_slider     = nullptr;
+    wxStaticText      *m_range_value      = nullptr;
+    wxStaticText      *m_presets_label    = nullptr;
+    wxScrolledWindow  *m_presets_host     = nullptr;
+    wxWrapSizer       *m_presets_sizer    = nullptr;
+    wxPanel           *m_loading_panel    = nullptr;
+    wxStaticText      *m_loading_label    = nullptr;
+    wxGauge           *m_loading_gauge    = nullptr;
+    wxPanel           *m_selected_preview = nullptr;
+    wxStaticText      *m_selected_label   = nullptr;
+    wxPanel           *m_recipe_preview   = nullptr;
+    wxStaticText      *m_recipe_label     = nullptr;
+    wxStaticText      *m_delta_label      = nullptr;
+    wxStaticText      *m_error_label      = nullptr;
+
+    // State
+    wxColour                    m_requested_target { wxColour("#26A69A") };
+    wxColour                    m_selected_target  { wxColour("#26A69A") };
+    MixedColorMatchRecipeResult m_selected_recipe;
+    wxTimer                     m_recipe_timer;
+    wxTimer                     m_loading_timer;
+    wxString                    m_loading_message;
+    size_t                      m_recipe_request_token   { 0 };
+    int                         m_min_component_percent  { 15 };
+    bool                        m_has_recipe_result      { false };
+    bool                        m_recipe_loading         { false };
+    bool                        m_recipe_refresh_pending { false };
+    bool                        m_syncing_inputs         { false };
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedFilamentConfigPanel.hpp

@@ -0,0 +1,129 @@
+#pragma once
+#include <wx/panel.h>
+#include <wx/checkbox.h>
+#include <wx/choice.h>
+#include <wx/spinctrl.h>
+#include <wx/stattext.h>
+#include <wx/textctrl.h>
+#include <vector>
+#include <string>
+#include <functional>
+#include <memory>
+#include "libslic3r/MixedFilament.hpp"
+
+namespace Slic3r { namespace GUI {
+
+class MixedMixPreview;       // Task 15
+class MixedGradientSelector; // Task 16
+
+// ---------------------------------------------------------------------------
+// MixedFilamentConfigPanel
+//
+// Inline per-row editor for a single MixedFilament entry.  Composes
+// MixedMixPreview, MixedGradientSelector and MixedGradientWeightsDialog.
+//
+// Extracted from FullSpectrum Plater.cpp:4588-6857.
+// ---------------------------------------------------------------------------
+class MixedFilamentConfigPanel : public wxPanel
+{
+public:
+    using OnChangeFn = std::function<void(const MixedFilament &)>;
+
+    MixedFilamentConfigPanel(wxWindow *parent,
+                             size_t mixed_id,
+                             const MixedFilament &mf,
+                             size_t num_physical,
+                             const std::vector<std::string> &physical_colors,
+                             const std::vector<double> &nozzle_diameters,
+                             const std::vector<wxColour> &palette,
+                             const MixedFilamentPreviewSettings &preview_settings,
+                             bool bias_mode_enabled,
+                             OnChangeFn on_change = {});
+
+    // Get the updated mixed filament data.
+    MixedFilament get_mixed_filament() const { return m_mf; }
+    bool has_changes() const { return m_has_changes; }
+
+    static int effective_local_z_preview_mix_b_percent(const MixedFilament &mf,
+                                                       const MixedFilamentPreviewSettings &preview_settings);
+
+private:
+    void build_ui();
+    void update_preview();
+    void update_local_z_breakdown();
+    void update_component_picker_visuals();
+
+    // Static helpers — verbatim from FullSpectrum Plater.cpp:4943-6042.
+    static std::vector<unsigned int> decode_gradient_ids(const std::string &s);
+    static std::string               encode_gradient_ids(const std::vector<unsigned int> &ids);
+    static std::vector<unsigned int> decode_manual_pattern_ids(const std::string &pattern,
+                                                               unsigned int       a,
+                                                               unsigned int       b,
+                                                               size_t             num_physical,
+                                                               size_t             wall_loops = 0);
+    static std::vector<int>          decode_gradient_weights(const std::string &s, size_t n);
+    static std::vector<int>          normalize_gradient_weights(const std::vector<int> &w, size_t n);
+    static std::string               encode_gradient_weights(const std::vector<int> &w);
+    static std::vector<unsigned int> build_weighted_pair_sequence(unsigned int a, unsigned int b, int percent_b, bool limit_cycle = false);
+    static std::vector<unsigned int> build_weighted_multi_sequence(const std::vector<unsigned int> &ids,
+                                                                   const std::vector<int> &weights,
+                                                                   size_t max_cycle_limit = 0);
+    static std::string               summarize_sequence(const std::vector<unsigned int> &seq);
+    static std::string               summarize_local_z_breakdown(const MixedFilament &mf,
+                                                                 const std::vector<int> &weights,
+                                                                 const MixedFilamentPreviewSettings &preview_settings);
+    static std::string               blend_from_sequence(const std::vector<std::string> &colors,
+                                                         const std::vector<unsigned int> &seq,
+                                                         const std::string &fallback);
+    static std::vector<double>       build_local_z_preview_pass_heights(double nominal_layer_height,
+                                                                        double lower_bound,
+                                                                        double upper_bound,
+                                                                        double preferred_a_height,
+                                                                        double preferred_b_height,
+                                                                        int mix_b_percent,
+                                                                        int max_sublayers_limit);
+
+    size_t                          m_mixed_id;
+    MixedFilament                   m_mf;
+    size_t                          m_num_physical;
+    std::vector<std::string>        m_physical_colors;
+    std::vector<double>             m_nozzle_diameters;
+    std::vector<wxColour>           m_palette;
+    MixedFilamentPreviewSettings    m_preview_settings;
+    bool                            m_bias_mode_enabled = false;
+    bool                            m_has_changes       = false;
+
+    wxChoice                       *m_choice_a = nullptr;
+    wxChoice                       *m_choice_b = nullptr;
+    wxChoice                       *m_choice_c = nullptr;
+    wxChoice                       *m_choice_d = nullptr;
+    wxPanel                        *m_picker_a_container = nullptr;
+    wxPanel                        *m_picker_b_container = nullptr;
+    wxPanel                        *m_picker_c_container = nullptr;
+    wxPanel                        *m_picker_d_container = nullptr;
+    wxPanel                        *m_picker_a_swatch = nullptr;
+    wxPanel                        *m_picker_b_swatch = nullptr;
+    wxPanel                        *m_picker_c_swatch = nullptr;
+    wxPanel                        *m_picker_d_swatch = nullptr;
+    wxStaticText                   *m_picker_a_label = nullptr;
+    wxStaticText                   *m_picker_b_label = nullptr;
+    wxStaticText                   *m_picker_c_label = nullptr;
+    wxStaticText                   *m_picker_d_label = nullptr;
+    wxPanel                        *m_surface_offset_target_container = nullptr;
+    wxPanel                        *m_surface_offset_target_swatch    = nullptr;
+    wxStaticText                   *m_surface_offset_target_label     = nullptr;
+    MixedGradientSelector          *m_blend_selector = nullptr;
+    wxStaticText                   *m_blend_label    = nullptr;
+    wxTextCtrl                     *m_pattern_ctrl   = nullptr;
+    wxCheckBox                     *m_local_z_limit_checkbox = nullptr;
+    wxSpinCtrl                     *m_local_z_limit_spin     = nullptr;
+    wxSpinCtrlDouble               *m_surface_offset_spin    = nullptr;
+    std::vector<wxButton *>         m_pattern_quick_buttons;
+    MixedMixPreview                *m_mix_preview    = nullptr;
+    wxStaticText                   *m_breakdown_label = nullptr;
+    wxPanel                        *m_swatch          = nullptr;
+    std::shared_ptr<std::vector<int>> m_selected_weight_state;
+    OnChangeFn                       m_on_change;
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedGradientSelector.cpp

@@ -0,0 +1,272 @@
+#include "MixedGradientSelector.hpp"
+#include "GUI_App.hpp"            // wxGetApp() / dark_mode()
+#include "I18N.hpp"               // _L()
+#include "Widgets/Label.hpp"      // Label::Body_10
+#include "libslic3r/filament_mixer.h"  // filament_mixer_lerp
+
+#include <wx/dcbuffer.h>
+#include <algorithm>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// Anonymous-namespace helper: copied verbatim from FullSpectrum Plater.cpp:2424
+// ---------------------------------------------------------------------------
+namespace {
+
+wxColour blend_pair_filament_mixer(const wxColour &left, const wxColour &right, float t)
+{
+    const wxColour safe_left  = left.IsOk()  ? left  : wxColour("#26A69A");
+    const wxColour safe_right = right.IsOk() ? right : wxColour("#26A69A");
+
+    unsigned char out_r = static_cast<unsigned char>(safe_left.Red());
+    unsigned char out_g = static_cast<unsigned char>(safe_left.Green());
+    unsigned char out_b = static_cast<unsigned char>(safe_left.Blue());
+    ::Slic3r::filament_mixer_lerp(static_cast<unsigned char>(safe_left.Red()),
+                                  static_cast<unsigned char>(safe_left.Green()),
+                                  static_cast<unsigned char>(safe_left.Blue()),
+                                  static_cast<unsigned char>(safe_right.Red()),
+                                  static_cast<unsigned char>(safe_right.Green()),
+                                  static_cast<unsigned char>(safe_right.Blue()),
+                                  std::clamp(t, 0.f, 1.f),
+                                  &out_r, &out_g, &out_b);
+    return wxColour(out_r, out_g, out_b);
+}
+
+} // anonymous namespace
+
+// ---------------------------------------------------------------------------
+// Constructor / destructor
+// ---------------------------------------------------------------------------
+
+MixedGradientSelector::MixedGradientSelector(wxWindow       *parent,
+                                              const wxColour &left,
+                                              const wxColour &right,
+                                              int             value_percent)
+    : wxPanel(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE)
+    , m_left(left)
+    , m_right(right)
+    , m_value(std::clamp(value_percent, 0, 100))
+{
+    SetBackgroundStyle(wxBG_STYLE_PAINT);
+    SetMinSize(wxSize(FromDIP(96), FromDIP(12)));
+    Bind(wxEVT_PAINT,              &MixedGradientSelector::on_paint,        this);
+    Bind(wxEVT_LEFT_DOWN,          &MixedGradientSelector::on_left_down,    this);
+    Bind(wxEVT_LEFT_UP,            &MixedGradientSelector::on_left_up,      this);
+    Bind(wxEVT_MOTION,             &MixedGradientSelector::on_mouse_move,   this);
+    Bind(wxEVT_MOUSE_CAPTURE_LOST, &MixedGradientSelector::on_capture_lost, this);
+}
+
+MixedGradientSelector::~MixedGradientSelector()
+{
+    if (HasCapture())
+        ReleaseMouse();
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+void MixedGradientSelector::set_colors(const wxColour &left, const wxColour &right)
+{
+    m_left  = left;
+    m_right = right;
+    m_multi_mode = false;
+    m_multi_colors.clear();
+    m_multi_weights.clear();
+    Refresh();
+}
+
+void MixedGradientSelector::set_multi_preview(const std::vector<wxColour> &corner_colors,
+                                               const std::vector<int>       &weights)
+{
+    m_multi_mode    = corner_colors.size() >= 3;
+    m_multi_colors  = corner_colors;
+    m_multi_weights = weights;
+    Refresh();
+}
+
+// ---------------------------------------------------------------------------
+// Private helpers
+// ---------------------------------------------------------------------------
+
+wxRect MixedGradientSelector::gradient_rect() const
+{
+    const int margin_x = FromDIP(2);
+    const int margin_y = FromDIP(1);
+    const wxSize sz    = GetClientSize();
+    return wxRect(margin_x, margin_y,
+                  std::max(1, sz.GetWidth()  - margin_x * 2),
+                  std::max(1, sz.GetHeight() - margin_y * 2));
+}
+
+int MixedGradientSelector::value_from_x(int x) const
+{
+    const wxRect rect    = gradient_rect();
+    const int    min_x   = rect.GetLeft();
+    const int    max_x   = rect.GetLeft() + rect.GetWidth();
+    const int    clamp_x = std::clamp(x, min_x, max_x);
+    return ((clamp_x - min_x) * 100 + rect.GetWidth() / 2) / rect.GetWidth();
+}
+
+void MixedGradientSelector::update_from_x(int x, bool notify)
+{
+    m_value = value_from_x(x);
+    Refresh();
+
+    if (notify) {
+        wxCommandEvent evt(wxEVT_SLIDER, GetId());
+        evt.SetInt(m_value);
+        evt.SetEventObject(this);
+        ProcessWindowEvent(evt);
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Event handlers
+// ---------------------------------------------------------------------------
+
+void MixedGradientSelector::on_paint(wxPaintEvent &)
+{
+    wxAutoBufferedPaintDC dc(this);
+    dc.SetBackground(wxBrush(GetBackgroundColour()));
+    dc.Clear();
+    const bool is_dark = wxGetApp().dark_mode();
+
+    const wxRect rect = gradient_rect();
+    if (m_multi_mode && m_multi_colors.size() >= 3) {
+        const wxPoint tl(rect.GetLeft(),                          rect.GetTop());
+        const wxPoint tr(rect.GetRight(),                         rect.GetTop());
+        const wxPoint br(rect.GetRight(),                         rect.GetBottom());
+        const wxPoint bl(rect.GetLeft(),                          rect.GetBottom());
+        const wxPoint cc(rect.GetLeft() + rect.GetWidth()  / 2,
+                         rect.GetTop()  + rect.GetHeight() / 2);
+
+        auto draw_tri = [&dc](const wxColour &color,
+                               const wxPoint  &a,
+                               const wxPoint  &b,
+                               const wxPoint  &c) {
+            wxPoint pts[3] = { a, b, c };
+            dc.SetPen(*wxTRANSPARENT_PEN);
+            dc.SetBrush(wxBrush(color));
+            dc.DrawPolygon(3, pts);
+        };
+
+        if (m_multi_colors.size() >= 4) {
+            draw_tri(m_multi_colors[0], tl, tr, cc);
+            draw_tri(m_multi_colors[1], tr, br, cc);
+            draw_tri(m_multi_colors[2], br, bl, cc);
+            draw_tri(m_multi_colors[3], bl, tl, cc);
+        } else {
+            // 3-colour layout: first colour occupies one full side, two others on the opposite corners.
+            draw_tri(m_multi_colors[0], tl, bl, cc);
+            draw_tri(m_multi_colors[1], tl, tr, cc);
+            draw_tri(m_multi_colors[2], bl, br, cc);
+        }
+
+        if (m_multi_weights.size() == m_multi_colors.size()) {
+            dc.SetTextForeground(is_dark ? wxColour(236, 236, 236) : wxColour(20, 20, 20));
+            dc.SetFont(Label::Body_10);
+            const int pad = FromDIP(2);
+            if (m_multi_colors.size() >= 4) {
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[0]),
+                            rect.GetLeft()  + pad,         rect.GetTop()    + pad);
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[1]),
+                            rect.GetRight() - FromDIP(28), rect.GetTop()    + pad);
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[2]),
+                            rect.GetRight() - FromDIP(28), rect.GetBottom() - FromDIP(14));
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[3]),
+                            rect.GetLeft()  + pad,         rect.GetBottom() - FromDIP(14));
+            } else {
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[0]),
+                            rect.GetLeft()  + pad,
+                            rect.GetTop()   + rect.GetHeight() / 2 - FromDIP(6));
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[1]),
+                            rect.GetRight() - FromDIP(28), rect.GetTop()    + pad);
+                dc.DrawText(wxString::Format("%d%%", m_multi_weights[2]),
+                            rect.GetRight() - FromDIP(28), rect.GetBottom() - FromDIP(14));
+            }
+        }
+    } else {
+        const int w = rect.GetWidth();
+        const int h = rect.GetHeight();
+        wxImage img(w, h);
+        unsigned char *data = img.GetData();
+        if (data != nullptr) {
+            for (int x = 0; x < w; ++x) {
+                const float    t   = (w > 1) ? float(x) / float(w - 1) : 0.5f;
+                const wxColour col = blend_pair_filament_mixer(m_left, m_right, t);
+                const unsigned char r = static_cast<unsigned char>(col.Red());
+                const unsigned char g = static_cast<unsigned char>(col.Green());
+                const unsigned char b = static_cast<unsigned char>(col.Blue());
+                for (int y = 0; y < h; ++y) {
+                    const int idx = (y * w + x) * 3;
+                    data[idx + 0] = r;
+                    data[idx + 1] = g;
+                    data[idx + 2] = b;
+                }
+            }
+            dc.DrawBitmap(wxBitmap(img), rect.GetLeft(), rect.GetTop(), false);
+        } else {
+            dc.GradientFillLinear(rect, m_left, m_right, wxEAST);
+        }
+    }
+
+    dc.SetPen(wxPen(is_dark ? wxColour(100, 100, 106) : wxColour(170, 170, 170), 1));
+    dc.SetBrush(*wxTRANSPARENT_BRUSH);
+    dc.DrawRectangle(rect);
+
+    if (m_multi_mode) {
+        dc.SetTextForeground(is_dark ? wxColour(236, 236, 236) : wxColour(30, 30, 30));
+        dc.SetFont(Label::Body_10);
+        const wxString hint    = _L("Click to edit");
+        wxSize         text_sz = dc.GetTextExtent(hint);
+        dc.DrawText(hint, rect.GetRight() - text_sz.GetWidth() - FromDIP(4), rect.GetTop() + FromDIP(2));
+        return;
+    }
+
+    int marker_x = rect.GetLeft() + (rect.GetWidth() * m_value + 50) / 100;
+    marker_x = std::clamp(marker_x, rect.GetLeft(), rect.GetRight());
+    dc.SetPen(wxPen(wxColour(255, 255, 255), 3));
+    dc.DrawLine(marker_x, rect.GetTop(), marker_x, rect.GetBottom());
+    dc.SetPen(wxPen(wxColour(33, 33, 33), 1));
+    dc.DrawLine(marker_x, rect.GetTop(), marker_x, rect.GetBottom());
+}
+
+void MixedGradientSelector::on_left_down(wxMouseEvent &evt)
+{
+    if (m_multi_mode)
+        return;
+    if (!HasCapture())
+        CaptureMouse();
+    m_dragging = true;
+    update_from_x(evt.GetX(), false);
+}
+
+void MixedGradientSelector::on_left_up(wxMouseEvent &evt)
+{
+    if (m_multi_mode) {
+        wxCommandEvent click_evt(wxEVT_BUTTON, GetId());
+        click_evt.SetEventObject(this);
+        ProcessWindowEvent(click_evt);
+        return;
+    }
+    if (m_dragging)
+        update_from_x(evt.GetX(), true);
+    m_dragging = false;
+    if (HasCapture())
+        ReleaseMouse();
+}
+
+void MixedGradientSelector::on_mouse_move(wxMouseEvent &evt)
+{
+    if (m_dragging && evt.LeftIsDown())
+        update_from_x(evt.GetX(), false);
+}
+
+void MixedGradientSelector::on_capture_lost(wxMouseCaptureLostEvent &)
+{
+    m_dragging = false;
+}
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedGradientSelector.hpp

@@ -0,0 +1,61 @@
+#pragma once
+#include <wx/panel.h>
+#include <wx/colour.h>
+#include <vector>
+#include <functional>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// MixedGradientSelector
+//
+// A small horizontal panel that renders a two-colour gradient (or a
+// multi-colour preview in "multi mode") and lets the user drag a marker
+// to pick a blend percentage.  In multi mode the panel renders coloured
+// triangles showing corner weights and emits wxEVT_BUTTON on click so the
+// owner can open MixedGradientWeightsDialog.
+//
+// Extracted from FullSpectrum Plater.cpp:4290-4505.
+// ---------------------------------------------------------------------------
+class MixedGradientSelector : public wxPanel
+{
+public:
+    MixedGradientSelector(wxWindow *parent,
+                          const wxColour &left,
+                          const wxColour &right,
+                          int             value_percent);
+
+    ~MixedGradientSelector() override;
+
+    // Current blend value 0-100.
+    int  value()        const { return m_value; }
+    bool is_multi_mode() const { return m_multi_mode; }
+
+    // Switch to two-colour gradient mode.
+    void set_colors(const wxColour &left, const wxColour &right);
+
+    // Switch to multi-colour preview mode (>= 3 corner colours required).
+    void set_multi_preview(const std::vector<wxColour> &corner_colors,
+                           const std::vector<int>       &weights);
+
+private:
+    wxRect gradient_rect() const;
+    int    value_from_x(int x) const;
+    void   update_from_x(int x, bool notify);
+
+    void on_paint(wxPaintEvent &evt);
+    void on_left_down(wxMouseEvent &evt);
+    void on_left_up(wxMouseEvent &evt);
+    void on_mouse_move(wxMouseEvent &evt);
+    void on_capture_lost(wxMouseCaptureLostEvent &evt);
+
+    wxColour              m_left;
+    wxColour              m_right;
+    bool                  m_multi_mode   { false };
+    std::vector<wxColour> m_multi_colors;
+    std::vector<int>      m_multi_weights;
+    int                   m_value        { 50 };
+    bool                  m_dragging     { false };
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedGradientWeightsDialog.cpp

@@ -0,0 +1,150 @@
+#include "MixedGradientWeightsDialog.hpp"
+#include "MixedFilamentColorMapPanel.hpp"
+#include "I18N.hpp"             // _L()
+#include "Widgets/Label.hpp"    // Label::Body_12
+
+#include <wx/sizer.h>
+#include <wx/stattext.h>
+#include <wx/panel.h>
+#include <algorithm>
+#include <cmath>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// Anonymous-namespace helper: copied verbatim from FullSpectrum Plater.cpp:2558
+// ---------------------------------------------------------------------------
+namespace {
+
+std::vector<int> normalize_color_match_weights(const std::vector<int> &weights, size_t count)
+{
+    std::vector<int> out = weights;
+    if (out.size() != count)
+        out.assign(count, count > 0 ? int(100 / int(count)) : 0);
+
+    int sum = 0;
+    for (int &value : out) {
+        value = std::max(0, value);
+        sum += value;
+    }
+    if (sum <= 0 && count > 0) {
+        out.assign(count, 0);
+        out[0] = 100;
+        return out;
+    }
+
+    std::vector<double> remainders(count, 0.0);
+    int assigned = 0;
+    for (size_t idx = 0; idx < count; ++idx) {
+        const double exact = 100.0 * double(out[idx]) / double(sum);
+        out[idx]           = int(std::floor(exact));
+        remainders[idx]    = exact - double(out[idx]);
+        assigned          += out[idx];
+    }
+
+    int missing = std::max(0, 100 - assigned);
+    while (missing > 0) {
+        size_t best_idx       = 0;
+        double best_remainder = -1.0;
+        for (size_t idx = 0; idx < remainders.size(); ++idx) {
+            if (remainders[idx] > best_remainder) {
+                best_remainder = remainders[idx];
+                best_idx       = idx;
+            }
+        }
+        ++out[best_idx];
+        remainders[best_idx] = 0.0;
+        --missing;
+    }
+
+    return out;
+}
+
+} // anonymous namespace
+
+// ---------------------------------------------------------------------------
+// Constructor — verbatim from FullSpectrum Plater.cpp:4506-4583
+// ---------------------------------------------------------------------------
+MixedGradientWeightsDialog::MixedGradientWeightsDialog(
+    wxWindow                        *parent,
+    const std::vector<unsigned int> &filament_ids,
+    const std::vector<wxColour>     &palette,
+    const std::vector<int>          &initial_weights)
+    : wxDialog(parent, wxID_ANY, _L("Gradient Mix Weights"),
+               wxDefaultPosition, wxDefaultSize,
+               wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER)
+{
+    m_colors.reserve(filament_ids.size());
+    m_weights = normalize_color_match_weights(initial_weights, filament_ids.size());
+    for (const unsigned int filament_id : filament_ids) {
+        if (filament_id >= 1 && filament_id <= palette.size())
+            m_colors.emplace_back(palette[filament_id - 1]);
+        else
+            m_colors.emplace_back(wxColour("#26A69A"));
+    }
+    if (m_colors.empty())
+        m_colors.emplace_back(wxColour("#26A69A"));
+
+    auto *root = new wxBoxSizer(wxVERTICAL);
+    auto *hint = new wxStaticText(this, wxID_ANY,
+        _L("Pick a point in the gradient map to control multi-filament mix."));
+    root->Add(hint, 0, wxEXPAND | wxALL, FromDIP(10));
+
+    m_color_map = new MixedFilamentColorMapPanel(this, filament_ids, palette, initial_weights,
+                                                 wxSize(FromDIP(240), FromDIP(240)));
+    root->Add(m_color_map, 1, wxEXPAND | wxLEFT | wxRIGHT | wxBOTTOM, FromDIP(10));
+
+    for (size_t i = 0; i < filament_ids.size(); ++i) {
+        auto  *row  = new wxBoxSizer(wxHORIZONTAL);
+        wxPanel *chip = new wxPanel(this, wxID_ANY, wxDefaultPosition,
+                                    wxSize(FromDIP(18), FromDIP(18)), wxBORDER_SIMPLE);
+        chip->SetBackgroundColour(m_colors[i]);
+        row->Add(chip, 0, wxALIGN_CENTER_VERTICAL | wxRIGHT, FromDIP(6));
+        row->Add(new wxStaticText(this, wxID_ANY,
+                                  wxString::Format("F%d", int(filament_ids[i]))),
+                 0, wxALIGN_CENTER_VERTICAL | wxRIGHT, FromDIP(8));
+        auto *label = new wxStaticText(this, wxID_ANY,
+                                       wxString::Format("%d%%", m_weights[i]));
+        label->SetFont(Label::Body_12);
+        row->Add(label, 0, wxALIGN_CENTER_VERTICAL);
+        root->Add(row, 0, wxEXPAND | wxLEFT | wxRIGHT | wxBOTTOM, FromDIP(8));
+        m_weight_labels.emplace_back(label);
+    }
+
+    root->Add(CreateSeparatedButtonSizer(wxOK | wxCANCEL), 0, wxEXPAND | wxALL, FromDIP(8));
+    SetSizerAndFit(root);
+    SetMinSize(wxSize(FromDIP(380),
+                      std::max(GetSize().GetHeight(), FromDIP(460))));
+    update_weight_labels();
+
+    if (m_color_map) {
+        m_color_map->Bind(wxEVT_SLIDER, [this](wxCommandEvent &) {
+            m_weights = m_color_map ? m_color_map->normalized_weights() : m_weights;
+            update_weight_labels();
+        });
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+std::vector<int> MixedGradientWeightsDialog::normalized_weights() const
+{
+    return m_color_map ? m_color_map->normalized_weights() : m_weights;
+}
+
+// ---------------------------------------------------------------------------
+// Private helpers
+// ---------------------------------------------------------------------------
+
+void MixedGradientWeightsDialog::update_weight_labels()
+{
+    for (size_t i = 0; i < m_weight_labels.size() && i < m_weights.size(); ++i) {
+        if (m_weight_labels[i])
+            m_weight_labels[i]->SetLabel(wxString::Format("%d%%", m_weights[i]));
+    }
+    Layout();
+}
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedGradientWeightsDialog.hpp

@@ -0,0 +1,45 @@
+#pragma once
+#include <wx/dialog.h>
+#include <wx/colour.h>
+#include <wx/stattext.h>
+#include <vector>
+
+namespace Slic3r { namespace GUI {
+
+// Forward-declare Task-17 panel: defined in MixedFilamentColorMapPanel.hpp.
+class MixedFilamentColorMapPanel;
+
+// ---------------------------------------------------------------------------
+// MixedGradientWeightsDialog
+//
+// A modal dialog that shows a MixedFilamentColorMapPanel and per-filament
+// weight labels so the user can pick multi-filament blend weights for a
+// gradient mix.
+//
+// Extracted from FullSpectrum Plater.cpp:4506-4583.
+//
+// NOTE (Task 17 dependency): the constructor body that instantiates
+// MixedFilamentColorMapPanel is guarded with #if 0 until Task 17 lands.
+// See MixedGradientWeightsDialog.cpp for details.
+// ---------------------------------------------------------------------------
+class MixedGradientWeightsDialog : public wxDialog
+{
+public:
+    MixedGradientWeightsDialog(wxWindow                        *parent,
+                               const std::vector<unsigned int> &filament_ids,
+                               const std::vector<wxColour>     &palette,
+                               const std::vector<int>          &initial_weights);
+
+    // Returns the normalised per-filament weight vector chosen by the user.
+    std::vector<int> normalized_weights() const;
+
+private:
+    void update_weight_labels();
+
+    MixedFilamentColorMapPanel  *m_color_map     { nullptr };
+    std::vector<wxColour>        m_colors;
+    std::vector<int>             m_weights;
+    std::vector<wxStaticText *>  m_weight_labels;
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedMixPreview.cpp

@@ -0,0 +1,181 @@
+#include "MixedMixPreview.hpp"
+#include "GUI_App.hpp"         // wxGetApp() / dark_mode()
+
+#include <wx/dcbuffer.h>       // wxAutoBufferedPaintDC
+#include <algorithm>
+#include <cmath>
+
+namespace Slic3r { namespace GUI {
+
+// ---------------------------------------------------------------------------
+// Constructor
+// ---------------------------------------------------------------------------
+
+MixedMixPreview::MixedMixPreview(wxWindow *parent)
+    : wxPanel(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE)
+{
+    SetBackgroundStyle(wxBG_STYLE_PAINT);
+    SetMinSize(wxSize(FromDIP(120), FromDIP(20)));
+    Bind(wxEVT_PAINT, &MixedMixPreview::on_paint, this);
+}
+
+// ---------------------------------------------------------------------------
+// Public API
+// ---------------------------------------------------------------------------
+
+void MixedMixPreview::set_data(const std::vector<wxColour>     &palette,
+                                const std::vector<unsigned int> &sequence,
+                                bool                             same_layer_mode,
+                                const std::vector<double>       &surface_offsets_mm,
+                                const wxColour                  &fallback,
+                                const wxString                  &left_overlay,
+                                const wxString                  &right_overlay)
+{
+    m_palette            = palette;
+    m_sequence           = sequence;
+    m_same_layer         = same_layer_mode;
+    m_surface_offsets_mm = surface_offsets_mm;
+    m_fallback           = fallback;
+    m_left_overlay       = left_overlay;
+    m_right_overlay      = right_overlay;
+    Refresh();
+}
+
+// ---------------------------------------------------------------------------
+// Private helpers
+// ---------------------------------------------------------------------------
+
+wxRect MixedMixPreview::preview_rect() const
+{
+    const int margin_x = FromDIP(1);
+    const int margin_y = FromDIP(1);
+    const wxSize sz    = GetClientSize();
+    return wxRect(margin_x, margin_y,
+                  std::max(1, sz.GetWidth()  - margin_x * 2),
+                  std::max(1, sz.GetHeight() - margin_y * 2));
+}
+
+wxColour MixedMixPreview::color_for_extruder(unsigned int extruder_id) const
+{
+    if (extruder_id >= 1 && extruder_id <= m_palette.size())
+        return m_palette[extruder_id - 1];
+    return m_fallback;
+}
+
+double MixedMixPreview::max_active_surface_offset_mm() const
+{
+    double max_offset = 0.0;
+    for (double offset_mm : m_surface_offsets_mm)
+        max_offset = std::max(max_offset, std::abs(offset_mm));
+    return std::max(0.001, max_offset);
+}
+
+int MixedMixPreview::slot_inset_for_extruder(unsigned int extruder_id, int slot_extent) const
+{
+    if (extruder_id == 0 || extruder_id >= m_surface_offsets_mm.size() || slot_extent <= 2)
+        return 0;
+
+    const double offset_mm = m_surface_offsets_mm[extruder_id];
+    if (std::abs(offset_mm) <= EPSILON)
+        return 0;
+
+    const double normalized = std::clamp(std::abs(offset_mm) / max_active_surface_offset_mm(), 0.0, 1.0);
+    const int inset = int(std::round(normalized * slot_extent * 0.45))
+                      * (offset_mm < 0.0 ? -1 : 1);
+    return std::clamp(inset,
+                      -std::max(0, slot_extent / 2),
+                       std::max(0, slot_extent / 2));
+}
+
+// ---------------------------------------------------------------------------
+// Paint handler
+// ---------------------------------------------------------------------------
+
+void MixedMixPreview::on_paint(wxPaintEvent &)
+{
+    wxAutoBufferedPaintDC dc(this);
+    dc.SetBackground(wxBrush(GetBackgroundColour()));
+    dc.Clear();
+
+    const wxRect rect = preview_rect();
+    dc.SetPen(*wxTRANSPARENT_PEN);
+    dc.SetBrush(wxBrush(m_fallback));
+    dc.DrawRectangle(rect);
+
+    if (!m_sequence.empty()) {
+        if (m_same_layer) {
+            // Same-layer preview: full-height stripe lines.
+            const int stripes  = 24;
+            const int stripe_w = std::max(1, rect.GetWidth() / stripes);
+            const size_t seq_len = m_sequence.size();
+            for (int s = 0; s < stripes; ++s) {
+                const size_t idx         = size_t(s % int(seq_len));
+                const unsigned int extruder_id = m_sequence[idx];
+                dc.SetBrush(wxBrush(color_for_extruder(extruder_id)));
+                const int x     = rect.GetLeft() + s * stripe_w;
+                const int w     = (s == stripes - 1) ? (rect.GetRight() - x + 1) : stripe_w;
+                const int inset = slot_inset_for_extruder(extruder_id, w);
+                wxRect draw_rect(x + inset / 2, rect.GetTop(),
+                                 std::max(1, w - inset), rect.GetHeight());
+                draw_rect.Intersect(rect);
+                if (draw_rect.GetWidth() > 0)
+                    dc.DrawRectangle(draw_rect);
+            }
+        } else {
+            const int bars  = 24;
+            const int bar_w = std::max(1, rect.GetWidth() / bars);
+            for (int i = 0; i < bars; ++i) {
+                size_t idx = 0;
+                if (m_sequence.size() > size_t(bars))
+                    idx = (size_t(i) * m_sequence.size()) / size_t(bars);
+                else
+                    idx = size_t(i) % m_sequence.size();
+                const unsigned int extruder_id = m_sequence[idx];
+                dc.SetBrush(wxBrush(color_for_extruder(extruder_id)));
+                const int x     = rect.GetLeft() + i * bar_w;
+                const int w     = (i == bars - 1) ? (rect.GetRight() - x + 1) : bar_w;
+                const int inset = slot_inset_for_extruder(extruder_id, w);
+                wxRect draw_rect(x + inset / 2, rect.GetTop(),
+                                 std::max(1, w - inset), rect.GetHeight());
+                draw_rect.Intersect(rect);
+                if (draw_rect.GetWidth() > 0)
+                    dc.DrawRectangle(draw_rect);
+            }
+        }
+    }
+
+    auto draw_outlined_text = [this, &dc](const wxString &text, int x, int y) {
+        if (text.empty())
+            return;
+        dc.SetTextForeground(wxColour(255, 255, 255));
+        const int outline_radius = std::max(2, FromDIP(2));
+        for (int ox = -outline_radius; ox <= outline_radius; ++ox) {
+            for (int oy = -outline_radius; oy <= outline_radius; ++oy) {
+                if (ox == 0 && oy == 0)
+                    continue;
+                dc.DrawText(text, x + ox, y + oy);
+            }
+        }
+        dc.SetTextForeground(wxColour(22, 22, 22));
+        dc.DrawText(text, x, y);
+    };
+
+    wxCoord left_w  = 0, left_h  = 0;
+    wxCoord right_w = 0, right_h = 0;
+    dc.GetTextExtent(m_left_overlay,  &left_w,  &left_h);
+    dc.GetTextExtent(m_right_overlay, &right_w, &right_h);
+    const int text_y = rect.GetTop()
+                       + std::max(0, (rect.GetHeight() - int(std::max(left_h, right_h))) / 2);
+    const int pad = FromDIP(6);
+    if (!m_left_overlay.empty())
+        draw_outlined_text(m_left_overlay, rect.GetLeft() + pad, text_y);
+    if (!m_right_overlay.empty())
+        draw_outlined_text(m_right_overlay, rect.GetRight() - pad - int(right_w), text_y);
+
+    const bool is_dark = wxGetApp().dark_mode();
+    dc.SetPen(wxPen(is_dark ? wxColour(110, 110, 110) : wxColour(170, 170, 170), 1));
+    dc.SetBrush(*wxTRANSPARENT_BRUSH);
+    dc.DrawRectangle(rect);
+}
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/MixedMixPreview.hpp

@@ -0,0 +1,41 @@
+#pragma once
+#include <wx/panel.h>
+#include <wx/colour.h>
+#include <vector>
+#include <string>
+
+namespace Slic3r { namespace GUI {
+
+// Preview strip that shows the layer-by-layer or same-layer colour sequence
+// produced by a mixed filament definition.  All logic is self-contained; the
+// owning panel calls set_data() whenever the underlying MixedFilament changes.
+class MixedMixPreview : public wxPanel
+{
+public:
+    explicit MixedMixPreview(wxWindow *parent);
+
+    void set_data(const std::vector<wxColour>       &palette,
+                  const std::vector<unsigned int>   &sequence,
+                  bool                               same_layer_mode,
+                  const std::vector<double>         &surface_offsets_mm,
+                  const wxColour                    &fallback,
+                  const wxString                    &left_overlay,
+                  const wxString                    &right_overlay);
+
+private:
+    wxRect   preview_rect() const;
+    wxColour color_for_extruder(unsigned int extruder_id) const;
+    double   max_active_surface_offset_mm() const;
+    int      slot_inset_for_extruder(unsigned int extruder_id, int slot_extent) const;
+    void     on_paint(wxPaintEvent &evt);
+
+    std::vector<wxColour>       m_palette;
+    std::vector<unsigned int>   m_sequence;
+    std::vector<double>         m_surface_offsets_mm;
+    bool                        m_same_layer    { false };
+    wxColour                    m_fallback      { wxColour(38, 166, 154) };
+    wxString                    m_left_overlay;
+    wxString                    m_right_overlay;
+};
+
+} } // namespace Slic3r::GUI

src/slic3r/GUI/NotificationManager.hpp

@@ -166,6 +166,8 @@ enum class NotificationType
     OrcaSharedProfilesAvailable,
 	OrcaCloudAPIError,
     OrcaSyncConflict,
+    BBLMixedFilamentBroken,
+    BBLSingleExtruderMixedFilamentRisk,
     NotificationTypeCount
 
 };

src/slic3r/GUI/ObjectDataViewModel.cpp

@@ -423,15 +423,31 @@ void ObjectDataViewModelNode::UpdateExtruderAndColorIcon(wxString extruder /*= "
         }
     }
 
+    const size_t extruder_id_1based = extruder_idx;
     if (extruder_idx > 0) --extruder_idx;
+
     // Create the bitmap with color bars.
     std::vector<wxBitmap*> bmps = get_extruder_color_icons(false);// use wide icons
-    if (bmps.empty()) {
-        m_extruder_bmp = wxNullBitmap;
+    if (!bmps.empty() && extruder_idx < bmps.size()) {
+        m_extruder_bmp = *bmps[extruder_idx];
         return;
     }
 
-    m_extruder_bmp = *bmps[extruder_idx >= bmps.size() ? 0 : extruder_idx];
+    // Fallback for mixed virtual filaments when the shared icon vector only covers physical filaments.
+    if (wxGetApp().plater() != nullptr) {
+        const std::vector<std::string> all_colors = wxGetApp().plater()->get_extruder_colors_from_plater_config(nullptr, true);
+        if (extruder_id_1based >= 1 && extruder_id_1based <= all_colors.size() && !all_colors[extruder_id_1based - 1].empty()) {
+            const double em = wxGetApp().em_unit();
+            const int    icon_width  = int(4.4 * em + 0.5);
+            const int    icon_height = int(2.0 * em + 0.5);
+            if (wxBitmap *bmp = get_extruder_color_icon(all_colors[extruder_id_1based - 1], std::to_string(extruder_id_1based), icon_width, icon_height)) {
+                m_extruder_bmp = *bmp;
+                return;
+            }
+        }
+    }
+
+    m_extruder_bmp = bmps.empty() ? wxNullBitmap : *bmps.front();
 }
 
 // *****************************************************************************

src/slic3r/GUI/PartPlate.cpp

@@ -4,6 +4,7 @@
 #include <vector>
 #include <string>
 #include <regex>
+#include <sstream>
 #include <future>
 #include <glad/gl.h>
 #include <boost/algorithm/string.hpp>
@@ -23,6 +24,7 @@
 #include "libslic3r/Tesselate.hpp"
 #include "libslic3r/GCode/ThumbnailData.hpp"
 #include "libslic3r/Utils.hpp"
+#include "libslic3r/MixedFilament.hpp"
 
 #include "I18N.hpp"
 #include "GUI_App.hpp"
@@ -1619,12 +1621,37 @@ std::vector<int> PartPlate::get_extruders(bool conside_custom_gcode) const
 	std::sort(plate_extruders.begin(), plate_extruders.end());
 	auto it_end = std::unique(plate_extruders.begin(), plate_extruders.end());
 	plate_extruders.resize(std::distance(plate_extruders.begin(), it_end));
-	return plate_extruders;
+
+	// Expand any mixed-filament virtual slots to their physical component extruders
+	{
+		const auto& mgr      = wxGetApp().preset_bundle->mixed_filaments;
+		size_t      num_phys = wxGetApp().preset_bundle->filament_presets.size();
+		std::vector<int> expanded;
+		for (int e : plate_extruders) {
+			if (e <= 0) continue;
+			auto u = static_cast<unsigned int>(e);
+			if (mgr.is_mixed(u, num_phys)) {
+				if (auto* mf = mgr.mixed_filament_from_id(u, num_phys)) {
+					expanded.push_back(static_cast<int>(mf->component_a));
+					expanded.push_back(static_cast<int>(mf->component_b));
+				}
+			} else {
+				expanded.push_back(e);
+			}
+		}
+		std::sort(expanded.begin(), expanded.end());
+		expanded.erase(std::unique(expanded.begin(), expanded.end()), expanded.end());
+		return expanded;
+	}
 }
 
 std::vector<int> PartPlate::get_extruders_under_cli(bool conside_custom_gcode, DynamicPrintConfig& full_config) const
 {
     std::vector<int> plate_extruders;
+    BOOST_LOG_TRIVIAL(debug) << "PartPlate::get_extruders_under_cli begin"
+                             << " plate=" << m_plate_index
+                             << " obj_to_instance_count=" << obj_to_instance_set.size()
+                             << " consider_custom_gcode=" << conside_custom_gcode;
 
     // if 3mf file
     int glb_support_intf_extr = full_config.opt_int("support_interface_filament");
@@ -1644,7 +1671,27 @@ std::vector<int> PartPlate::get_extruders_under_cli(bool conside_custom_gcode, D
         if ((obj_id >= 0) && (obj_id < m_model->objects.size()))
         {
             ModelObject* object = m_model->objects[obj_id];
+            if (object == nullptr) {
+                BOOST_LOG_TRIVIAL(error) << "PartPlate::get_extruders_under_cli encountered null model object"
+                                         << " plate=" << m_plate_index
+                                         << " obj_id=" << obj_id;
+                continue;
+            }
+            if (instance_id < 0 || instance_id >= object->instances.size()) {
+                BOOST_LOG_TRIVIAL(error) << "PartPlate::get_extruders_under_cli encountered invalid instance index"
+                                         << " plate=" << m_plate_index
+                                         << " obj_id=" << obj_id
+                                         << " instance_id=" << instance_id
+                                         << " instance_count=" << object->instances.size();
+                continue;
+            }
             ModelInstance* instance = object->instances[instance_id];
+            BOOST_LOG_TRIVIAL(debug) << "PartPlate::get_extruders_under_cli object"
+                                     << " plate=" << m_plate_index
+                                     << " obj_id=" << obj_id
+                                     << " instance_id=" << instance_id
+                                     << " volume_count=" << object->volumes.size()
+                                     << " printable=" << instance->printable;
 
             if (!instance->printable)
                 continue;
@@ -1741,7 +1788,45 @@ std::vector<int> PartPlate::get_extruders_under_cli(bool conside_custom_gcode, D
     std::sort(plate_extruders.begin(), plate_extruders.end());
     auto it_end = std::unique(plate_extruders.begin(), plate_extruders.end());
     plate_extruders.resize(std::distance(plate_extruders.begin(), it_end));
-    return plate_extruders;
+
+    // Expand any mixed-filament virtual slots to their physical component extruders.
+    // CLI context: rebuild the manager inline from full_config (no wxGetApp).
+    {
+        MixedFilamentManager local_mgr;
+        std::vector<std::string> filament_colours;
+        if (const auto* col_opt = dynamic_cast<const ConfigOptionStrings*>(full_config.option("filament_colour")))
+            filament_colours = col_opt->values;
+        local_mgr.auto_generate(filament_colours);
+        if (const auto* defs_opt = dynamic_cast<const ConfigOptionString*>(full_config.option("mixed_filament_definitions")))
+            if (!defs_opt->value.empty())
+                local_mgr.load_custom_entries(defs_opt->value, filament_colours);
+        size_t num_phys = filament_colours.size();
+        std::vector<int> expanded;
+        for (int e : plate_extruders) {
+            if (e <= 0) continue;
+            auto u = static_cast<unsigned int>(e);
+            if (local_mgr.is_mixed(u, num_phys)) {
+                if (auto* mf = local_mgr.mixed_filament_from_id(u, num_phys)) {
+                    expanded.push_back(static_cast<int>(mf->component_a));
+                    expanded.push_back(static_cast<int>(mf->component_b));
+                }
+            } else {
+                expanded.push_back(e);
+            }
+        }
+        std::sort(expanded.begin(), expanded.end());
+        expanded.erase(std::unique(expanded.begin(), expanded.end()), expanded.end());
+        std::ostringstream extruders_list;
+        for (size_t i = 0; i < expanded.size(); ++i) {
+            if (i != 0)
+                extruders_list << ",";
+            extruders_list << expanded[i];
+        }
+        BOOST_LOG_TRIVIAL(debug) << "PartPlate::get_extruders_under_cli result"
+                                 << " plate=" << m_plate_index
+                                 << " extruders=[" << extruders_list.str() << "]";
+        return expanded;
+    }
 }
 
 bool PartPlate::check_objects_empty_and_gcode3mf(std::vector<int> &result) const
@@ -1794,7 +1879,28 @@ std::vector<int> PartPlate::get_extruders_without_support(bool conside_custom_gc
 	std::sort(plate_extruders.begin(), plate_extruders.end());
 	auto it_end = std::unique(plate_extruders.begin(), plate_extruders.end());
 	plate_extruders.resize(std::distance(plate_extruders.begin(), it_end));
-	return plate_extruders;
+
+	// Expand any mixed-filament virtual slots to their physical component extruders
+	{
+		const auto& mgr      = wxGetApp().preset_bundle->mixed_filaments;
+		size_t      num_phys = wxGetApp().preset_bundle->filament_presets.size();
+		std::vector<int> expanded;
+		for (int e : plate_extruders) {
+			if (e <= 0) continue;
+			auto u = static_cast<unsigned int>(e);
+			if (mgr.is_mixed(u, num_phys)) {
+				if (auto* mf = mgr.mixed_filament_from_id(u, num_phys)) {
+					expanded.push_back(static_cast<int>(mf->component_a));
+					expanded.push_back(static_cast<int>(mf->component_b));
+				}
+			} else {
+				expanded.push_back(e);
+			}
+		}
+		std::sort(expanded.begin(), expanded.end());
+		expanded.erase(std::unique(expanded.begin(), expanded.end()), expanded.end());
+		return expanded;
+	}
 }
 
 /* -1 is invalid, return physical extruder idx*/
@@ -1821,6 +1927,8 @@ int PartPlate::get_physical_extruder_by_filament_id(const DynamicConfig& g_confi
 	}
 
 	int zero_base_logical_idx = filament_map[idx - 1] - 1;
+	if (zero_base_logical_idx < 0 || zero_base_logical_idx >= (int)the_map->values.size())
+		return -1;
 	return the_map->values[zero_base_logical_idx];
 }
 

src/slic3r/GUI/PlateSettingsDialog.cpp

@@ -216,6 +216,18 @@ OtherLayersSeqPanel::OtherLayersSeqPanel(wxWindow* parent)
     Layout();
     top_sizer->Fit(this);
 
+    // Disable custom sequence when mixed (virtual) filaments are in use.
+    {
+        size_t total    = wxGetApp().preset_bundle->total_filament_count();
+        size_t num_phys = wxGetApp().preset_bundle->filament_presets.size();
+        if (total > num_phys) {
+            m_other_layer_print_seq_choice->Disable();
+            auto* warn = new wxStaticText(this, wxID_ANY,
+                _L("Custom layer sequence is unavailable when mixed filaments are used."));
+            warn->SetForegroundColour(wxColour(255, 100, 0));
+            top_sizer->Add(warn, 0, wxALIGN_LEFT | wxTOP, FromDIP(4));
+        }
+    }
 
     m_other_layer_print_seq_choice->Bind(wxEVT_COMBOBOX, [this, buttons_sizer](auto& e) {
         if (e.GetSelection() == 0) {

src/slic3r/GUI/Plater.hpp

@@ -182,6 +182,14 @@ public:
     void on_filament_count_change(size_t num_filaments);
     void on_filaments_delete(size_t filament_id);
 
+    // Mixed Filaments panel
+    void update_mixed_filament_panel(bool sync_manager = true);
+    std::vector<unsigned int> get_ui_ordered_filament_ids() const;
+    // Returns true when any mixed filament references a component ID that is
+    // out of the physical filament range (e.g. after the user reduces the
+    // physical filament count).
+    bool has_broken_mixed_filament() const;
+
     void add_filament();
     void delete_filament(size_t filament_id = size_t(-1), int replace_filament_id = -1);  // 0 base, -1 means default
     void change_filament(size_t from_id, size_t to_id);  // 0 base
@@ -556,7 +564,18 @@ public:
 
     void on_filament_change(size_t filament_idx);
     void on_filament_count_change(size_t extruders_count);
-    void on_filaments_delete(size_t extruders_count, size_t filament_id, int replace_filament_id = -1);
+    void on_filaments_delete(size_t extruders_count, size_t filament_id, int replace_filament_id = -1,
+                             const std::vector<unsigned char>& is_mixed_before_delete = {});
+    // FullSpectrum: gate auto gradient generation when many physical filaments would create a large grid.
+    // Returns true when callers may proceed with auto-generated gradients. As a side effect, this
+    // call also sets MixedFilamentManager's static auto-generate flag to match the returned decision,
+    // so callers do not need to set it themselves. Pops a yes/no dialog at most once per
+    // physical-filament count (cached per Plater instance).
+    bool confirm_auto_generated_gradients(size_t num_physical);
+    // Force a decision into the prompt cache without showing a dialog. Pass num_physical = 0 to
+    // invalidate the cache (so the next genuine count-growth event re-prompts), or the current
+    // count to record the user's decision. Used by the Preferences toggle.
+    void set_auto_generated_gradient_decision(size_t num_physical, bool create_auto_gradients);
     std::vector<Slic3r::ColorRGBA> get_extruders_colors();
     // BBS
     void on_bed_type_change(BedType bed_type);
@@ -568,7 +587,7 @@ public:
     void force_print_bed_update();
     // On activating the parent window.
     void on_activate();
-    std::vector<std::string> get_extruder_colors_from_plater_config(const GCodeProcessorResult* const result = nullptr) const;
+    std::vector<std::string> get_extruder_colors_from_plater_config(const GCodeProcessorResult* const result = nullptr, bool include_mixed = true) const;
     std::vector<std::string> get_filament_colors_render_info() const;
     std::vector<std::string> get_filament_color_render_type() const;
     std::vector<std::string> get_colors_for_color_print(const GCodeProcessorResult* const result = nullptr) const;

src/slic3r/GUI/Preferences.cpp

@@ -7,6 +7,7 @@
 #include "I18N.hpp"
 #include "libslic3r/AppConfig.hpp"
 #include "libslic3r/Format/DRC.hpp"
+#include "libslic3r/MixedFilament.hpp"
 #include <wx/language.h>
 #include "OG_CustomCtrl.hpp"
 #include "wx/graphics.h"
@@ -1040,6 +1041,19 @@ wxBoxSizer *PreferencesDialog::create_item_checkbox(wxString title, wxString too
             }
         }
 
+        if (param == "auto_generate_gradients") {
+            MixedFilamentManager::set_auto_generate_enabled(checkbox->GetValue());
+            if (wxGetApp().preset_bundle != nullptr && wxGetApp().plater() != nullptr) {
+                const size_t num_physical = wxGetApp().preset_bundle->filament_presets.size();
+                // FullSpectrum: record the toggle as the user's authoritative decision for
+                // the current count, suppressing any future dialog at this same count.
+                // Adding more filaments later misses the cache and re-prompts as expected.
+                wxGetApp().plater()->set_auto_generated_gradient_decision(num_physical, checkbox->GetValue());
+                wxGetApp().preset_bundle->update_multi_material_filament_presets();
+                wxGetApp().plater()->on_filament_count_change(num_physical);
+            }
+        }
+
         if (param == "enable_high_low_temp_mixed_printing") {
             if (checkbox->GetValue()) {
                 const wxString warning_title = _L("Bed Temperature Difference Warning");
@@ -1479,6 +1493,9 @@ void PreferencesDialog::create_items()
     auto item_auto_flush = create_item_combobox(_L("Auto flush after changing..."), _L("Auto calculate flushing volumes when selected values changed"), "auto_calculate_flush", FlushOptionLabels, FlushOptionValues);
     g_sizer->Add(item_auto_flush);
 
+    auto item_auto_generate_gradients = create_item_checkbox(_L("Mixed filaments: Auto-generate gradients."), _L("If enabled, OrcaSlicer automatically creates gradient mixed filaments from physical filament pairs."), "auto_generate_gradients");
+    g_sizer->Add(item_auto_generate_gradients);
+
     auto item_auto_arrange     = create_item_checkbox(_L("Auto arrange plate after cloning"), "", "auto_arrange");
     g_sizer->Add(item_auto_arrange);
 

src/slic3r/GUI/Tab.cpp

@@ -1646,6 +1646,49 @@ void Tab::on_value_change(const std::string& opt_key, const boost::any& value)
         }
     }
 
+    if (opt_key == "dithering_local_z_mode") {
+        const bool local_z_enabled = boost::any_cast<bool>(value);
+        if (local_z_enabled &&
+            (!m_config->has("mixed_filament_region_collapse") ||
+             m_config->option("mixed_filament_region_collapse") == nullptr ||
+             m_config->opt_bool("mixed_filament_region_collapse"))) {
+            change_opt_value(*m_config, "mixed_filament_region_collapse", boost::any(false));
+            if (m_type == Preset::TYPE_PRINT) {
+                DynamicPrintConfig &project_cfg = wxGetApp().preset_bundle->project_config;
+                project_cfg.set_key_value("mixed_filament_region_collapse", new ConfigOptionBool(false));
+            }
+            if (Field *field = this->get_field("mixed_filament_region_collapse"))
+                field->set_value(boost::any(false), false);
+            update_dirty();
+        }
+        if (!local_z_enabled &&
+            m_config->has("dithering_local_z_whole_objects") &&
+            m_config->option("dithering_local_z_whole_objects") != nullptr &&
+            m_config->opt_bool("dithering_local_z_whole_objects")) {
+            change_opt_value(*m_config, "dithering_local_z_whole_objects", boost::any(false));
+            if (m_type == Preset::TYPE_PRINT) {
+                DynamicPrintConfig &project_cfg = wxGetApp().preset_bundle->project_config;
+                project_cfg.set_key_value("dithering_local_z_whole_objects", new ConfigOptionBool(false));
+            }
+            if (Field *field = this->get_field("dithering_local_z_whole_objects"))
+                field->set_value(boost::any(false), false);
+            update_dirty();
+        }
+        if (!local_z_enabled &&
+            m_config->has("dithering_local_z_direct_multicolor") &&
+            m_config->option("dithering_local_z_direct_multicolor") != nullptr &&
+            m_config->opt_bool("dithering_local_z_direct_multicolor")) {
+            change_opt_value(*m_config, "dithering_local_z_direct_multicolor", boost::any(false));
+            if (m_type == Preset::TYPE_PRINT) {
+                DynamicPrintConfig &project_cfg = wxGetApp().preset_bundle->project_config;
+                project_cfg.set_key_value("dithering_local_z_direct_multicolor", new ConfigOptionBool(false));
+            }
+            if (Field *field = this->get_field("dithering_local_z_direct_multicolor"))
+                field->set_value(boost::any(false), false);
+            update_dirty();
+        }
+    }
+
     // reload scene to update timelapse wipe tower
     if (opt_key == "timelapse_type") {
         bool wipe_tower_enabled = m_config->option<ConfigOptionBool>("enable_prime_tower")->value;
@@ -1961,10 +2004,42 @@ void Tab::on_value_change(const std::string& opt_key, const boost::any& value)
         return;
     }
 
+    const bool refresh_mixed_filament_panel =
+        m_type == Preset::TYPE_PRINT && opt_key == "mixed_filament_component_bias_enabled";
+
+    // Keep Mixed Filaments global settings in sync with project_config. In
+    // full_fff_config(), project_config is applied last and would otherwise
+    // override the edited print preset value from the Others panel.
+    if (m_type == Preset::TYPE_PRINT &&
+        (opt_key == "mixed_filament_gradient_mode" ||
+         opt_key == "mixed_filament_height_lower_bound" ||
+         opt_key == "mixed_filament_height_upper_bound" ||
+         opt_key == "mixed_color_layer_height_a" ||
+         opt_key == "mixed_color_layer_height_b" ||
+         opt_key == "mixed_filament_advanced_dithering" ||
+         opt_key == "mixed_filament_pointillism_pixel_size" ||
+         opt_key == "mixed_filament_pointillism_line_gap" ||
+         opt_key == "mixed_filament_component_bias_enabled" ||
+         opt_key == "mixed_filament_surface_indentation" ||
+         opt_key == "mixed_filament_region_collapse" ||
+         opt_key == "dithering_z_step_size" ||
+         opt_key == "dithering_local_z_mode" ||
+         opt_key == "dithering_local_z_whole_objects" ||
+         opt_key == "dithering_local_z_direct_multicolor" ||
+         opt_key == "dithering_step_painted_zones_only" ||
+         opt_key == "mixed_filament_definitions")) {
+        DynamicPrintConfig &project_cfg = wxGetApp().preset_bundle->project_config;
+        if (const ConfigOption *opt = m_config->option(opt_key))
+            project_cfg.set_key_value(opt_key, opt->clone());
+    }
+
     update();
     if(m_active_page)
         m_active_page->update_visibility(m_mode, true);
     m_page_view->GetParent()->Layout();
+
+    if (refresh_mixed_filament_panel && wxGetApp().plater() != nullptr)
+        wxGetApp().sidebar().update_mixed_filament_panel(false);
 }
 
 void Tab::show_timelapse_warning_dialog() {
@@ -2318,6 +2393,7 @@ void TabPrint::build()
         auto optgroup = page->new_optgroup(L("Layer height"), L"param_layer_height");
         optgroup->append_single_option_line("layer_height","quality_settings_layer_height");
         optgroup->append_single_option_line("initial_layer_print_height","quality_settings_layer_height");
+        optgroup->append_single_option_line("mixed_filament_gradient_mode");
 
         optgroup = page->new_optgroup(L("Line width"), L"param_line_width");
         optgroup->append_single_option_line("line_width","quality_settings_line_width");
@@ -2469,6 +2545,13 @@ void TabPrint::build()
         optgroup->append_single_option_line("fill_multiline", "strength_settings_infill#fill-multiline");
         optgroup->append_single_option_line("sparse_infill_pattern", "strength_settings_infill#sparse-infill-pattern");
         optgroup->append_single_option_line("gyroid_optimized", "strength_settings_patterns#gyroid-optimized");
+        if (m_type >= Preset::TYPE_COUNT) {
+            // Per-object / per-model only: infill filament override
+            optgroup->append_single_option_line("enable_infill_filament_override");
+            optgroup->append_single_option_line("infill_filament_use_base_first_layers");
+            optgroup->append_single_option_line("infill_filament_use_base_last_layers");
+            optgroup->append_single_option_line("sparse_infill_filament", "multimaterial_settings_filament_for_features#infill");
+        }
         optgroup->append_single_option_line("infill_direction", "strength_settings_infill#direction");
         optgroup->append_single_option_line("sparse_infill_rotate_template", "strength_settings_infill_rotation_template_metalanguage");
         optgroup->append_single_option_line("skin_infill_density", "strength_settings_patterns#locked-zag");
@@ -2663,6 +2746,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("wipe_tower_fillet_wall", "multimaterial_settings_prime_tower#fillet-wall");
         optgroup->append_single_option_line("wipe_tower_no_sparse_layers", "multimaterial_settings_prime_tower#no-sparse-layers");
         optgroup->append_single_option_line("single_extruder_multi_material_priming", "multimaterial_settings_prime_tower");
+        optgroup->append_single_option_line("local_z_wipe_tower_purge_lines", "multimaterial_settings_prime_tower");
 
         optgroup = page->new_optgroup(L("Filament for Features"), L"param_filament_for_features");
         optgroup->append_single_option_line("wall_filament", "multimaterial_settings_filament_for_features#walls");
@@ -2726,6 +2810,21 @@ void TabPrint::build()
         optgroup->append_single_option_line("timelapse_type", "others_settings_special_mode#timelapse");
         optgroup->append_single_option_line("enable_wrapping_detection");
 
+        // Mixed Filaments / Dithering settings
+        optgroup = page->new_optgroup(L("Dithering"));
+        optgroup->append_single_option_line("mixed_filament_height_lower_bound");
+        optgroup->append_single_option_line("mixed_filament_height_upper_bound");
+        optgroup->append_single_option_line("mixed_filament_advanced_dithering");
+        optgroup->append_single_option_line("mixed_filament_component_bias_enabled");
+        optgroup->append_single_option_line("mixed_filament_surface_indentation");
+        optgroup->append_single_option_line("mixed_filament_region_collapse");
+        optgroup->append_single_option_line("dithering_z_step_size");
+        optgroup->append_single_option_line("dithering_step_painted_zones_only");
+        // Local-Z subgroup (gated by dithering_local_z_mode)
+        optgroup->append_single_option_line("dithering_local_z_mode");
+        optgroup->append_single_option_line("dithering_local_z_whole_objects");
+        optgroup->append_single_option_line("dithering_local_z_direct_multicolor");
+
         optgroup = page->new_optgroup(L("Fuzzy Skin"), L"fuzzy_skin");
         optgroup->append_single_option_line("fuzzy_skin", "others_settings_fuzzy_skin");
         optgroup->append_single_option_line("fuzzy_skin_mode", "others_settings_fuzzy_skin#fuzzy-skin-mode");

src/slic3r/GUI/WipeTowerDialog.cpp

@@ -199,24 +199,71 @@ std::string RammingPanel::get_parameters()
 static const float g_min_flush_multiplier = 0.f;
 static const float g_max_flush_multiplier = 3.f;
 
+// Extract the num_phys×num_phys top-left block from a flat total×total matrix.
+// When there are no mixed filaments (total == num_phys) the function is a no-op
+// and returns the input unchanged.
+static std::vector<double> extract_physical_sub_matrix(
+    const std::vector<double>& full, size_t total, size_t num_phys)
+{
+    if (num_phys >= total || total == 0)
+        return full;
+    std::vector<double> phys(num_phys * num_phys, 0.0);
+    for (size_t row = 0; row < num_phys; ++row)
+        for (size_t col = 0; col < num_phys; ++col)
+            phys[row * num_phys + col] = full[row * total + col];
+    return phys;
+}
+
+// Write the edited num_phys×num_phys sub-matrix back into a copy of
+// original_full (total×total), preserving the mixed-slot rows and columns.
+static std::vector<double> expand_physical_to_full_matrix(
+    const std::vector<double>& phys, const std::vector<double>& original_full,
+    size_t total, size_t num_phys)
+{
+    if (num_phys >= total || total == 0)
+        return phys;
+    std::vector<double> result(original_full);  // preserve mixed rows/cols
+    for (size_t row = 0; row < num_phys; ++row)
+        for (size_t col = 0; col < num_phys; ++col)
+            result[row * total + col] = phys[row * num_phys + col];
+    return result;
+}
+
 bool is_flush_config_modified()
 {
     const auto                &project_config    = wxGetApp().preset_bundle->project_config;
     const std::vector<double> &config_matrix     = (project_config.option<ConfigOptionFloats>("flush_volumes_matrix"))->values;
     const std::vector<double> &config_multiplier = (project_config.option<ConfigOptionFloats>("flush_multiplier"))->values;
 
+    // Physical filament count (excludes mixed virtual slots).
+    const size_t num_phys = static_cast<size_t>(wxGetApp().filaments_cnt());
+    const size_t nozzle_num = config_multiplier.size();
+    // Total filament count stored per nozzle block.
+    const size_t total = (nozzle_num > 0 && !config_matrix.empty())
+                             ? static_cast<size_t>(std::round(std::sqrt(config_matrix.size() / nozzle_num)))
+                             : num_phys;
+
     bool has_modify = false;
-    for (int i = 0; i < config_multiplier.size(); i++) {
+    for (int i = 0; i < (int)nozzle_num; i++) {
         if (config_multiplier[i] != 1) {
             has_modify = true;
             break;
         }
+        // Extract the per-nozzle block from the flat full matrix.
+        std::vector<double> nozzle_full(config_matrix.begin() + i * (int)(total * total),
+                                        config_matrix.begin() + (i + 1) * (int)(total * total));
+        // Only compare the physical sub-matrix; mixed-slot rows/cols are computed.
+        const std::vector<double> phys_stored = extract_physical_sub_matrix(nozzle_full, total, num_phys);
+
         std::vector<std::vector<double>> default_matrix = WipingDialog::CalcFlushingVolumes(i);
-        int len = default_matrix.size();
-        for (int m = 0; m < len; m++) {
-            for (int n = 0; n < len; n++) {
-                int idx = i * len * len + m * len + n;
-                if (config_matrix[idx] != default_matrix[m][n] * config_multiplier[i]) {
+        // CalcFlushingVolumes also spans total×total; take physical sub-matrix.
+        int def_total = (int)default_matrix.size();
+        for (int m = 0; m < (int)num_phys; m++) {
+            for (int n = 0; n < (int)num_phys; n++) {
+                double def_val = (m < def_total && n < (int)default_matrix[m].size())
+                                     ? default_matrix[m][n] * config_multiplier[i]
+                                     : 0.0;
+                if (phys_stored[m * num_phys + n] != def_val) {
                     has_modify = true;
                     break;
                 }
@@ -265,24 +312,46 @@ wxString WipingDialog::BuildTableObjStr()
     auto raw_matrix_data = full_config.option<ConfigOptionFloats>("flush_volumes_matrix")->values;
     auto nozzle_flush_dataset = full_config.option<ConfigOptionIntsNullable>("nozzle_flush_dataset")->values;
 
-    std::vector<std::vector<double>> flush_matrixs;
+    // Physical filament count — the editor only shows the P×P physical block.
+    const size_t num_phys = static_cast<size_t>(wxGetApp().filaments_cnt());
+    const size_t total    = (num_phys > 0 && !filament_colors.empty())
+                                ? filament_colors.size()
+                                : num_phys;
+
+    // Per-nozzle full matrices (total×total), stored for expand-on-save.
+    std::vector<std::vector<double>> full_matrixs;
     for (int idx = 0; idx < nozzle_num; ++idx) {
-        flush_matrixs.emplace_back(get_flush_volumes_matrix(raw_matrix_data, idx, nozzle_num));
+        full_matrixs.emplace_back(get_flush_volumes_matrix(raw_matrix_data, idx, nozzle_num));
     }
     flush_multiplier.resize(nozzle_num, 1);
 
-    std::vector<std::vector<float>> default_matrixs;
+    // Physical sub-matrices sent to the web editor (num_phys×num_phys).
+    std::vector<std::vector<double>> flush_matrixs;
     for (int idx = 0; idx < nozzle_num; ++idx) {
-        default_matrixs.emplace_back(MatrixFlatten(CalcFlushingVolumes(idx)));
+        flush_matrixs.emplace_back(extract_physical_sub_matrix(full_matrixs[idx], total, num_phys));
     }
 
-    m_raw_matrixs = flush_matrixs;
+    // Default matrices for the auto-calc button — physical sub-matrix only.
+    std::vector<std::vector<float>> default_matrixs;
+    for (int idx = 0; idx < nozzle_num; ++idx) {
+        std::vector<float> def_flat = MatrixFlatten(CalcFlushingVolumes(idx));
+        std::vector<double> def_d(def_flat.begin(), def_flat.end());
+        std::vector<double> def_phys = extract_physical_sub_matrix(def_d, total, num_phys);
+        default_matrixs.emplace_back(def_phys.begin(), def_phys.end());
+    }
+
+    // Store full matrices so storeData can expand back when saving.
+    m_raw_matrixs = full_matrixs;
     m_flush_multipliers = flush_multiplier;
 
+    // Only send physical filament colours to the editor.
+    std::vector<std::string> phys_colors(filament_colors.begin(),
+                                          filament_colors.begin() + std::min(num_phys, filament_colors.size()));
+
     json obj;
     obj["flush_multiplier"] = flush_multiplier;
     obj["extruder_num"] = nozzle_num;
-    obj["filament_colors"] = filament_colors;
+    obj["filament_colors"] = phys_colors;
     obj["flush_volume_matrixs"] = json::array();
     obj["min_flush_volumes"] = json::array();
     obj["max_flush_volumes"] = json::array();
@@ -299,8 +368,12 @@ wxString WipingDialog::BuildTableObjStr()
     }
 
     for (int idx = 0; idx < nozzle_num; ++idx) {
+        // min_flush_volumes is indexed by physical slot; slice off at num_phys.
         const std::vector<int> &min_flush_volumes = get_min_flush_volumes(full_config, idx);
-        int min_flush_from_nozzle_volume = *min_element(min_flush_volumes.begin(), min_flush_volumes.end());
+        int min_flush_from_nozzle_volume = min_flush_volumes.empty()
+            ? 0
+            : *min_element(min_flush_volumes.begin(),
+                           min_flush_volumes.begin() + std::min(num_phys, min_flush_volumes.size()));
         GenericFlushPredictor pd(nozzle_flush_dataset[idx]);
         int min_flush_from_flush_data = pd.get_min_flush_volume();
         obj["min_flush_volumes"].push_back(std::min(min_flush_from_flush_data,min_flush_from_nozzle_volume));
@@ -468,26 +541,42 @@ WipingDialog::WipingDialog(wxWindow* parent, const int max_flush_volume) :
             }
             else if (j["msg"].get<std::string>() == "storeData") {
                 int extruder_num = j["number_of_extruders"].get<int>();
-                std::vector<std::vector<double>> store_matrixs;
+                // The web editor works on the physical sub-matrix (P×P).
+                std::vector<std::vector<double>> phys_matrixs;
                 for (auto iter = j["raw_matrix"].begin(); iter != j["raw_matrix"].end(); ++iter) {
-                    store_matrixs.emplace_back((*iter).get<std::vector<double>>());
+                    phys_matrixs.emplace_back((*iter).get<std::vector<double>>());
                 }
                 std::vector<double>store_multipliers = j["flush_multiplier"].get<std::vector<double>>();
                 {// limit all matrix value before write to gcode, the limitation is depends on the multipliers
                     size_t cols_temp_matrix = 0;
-                    if (!store_matrixs.empty()) { cols_temp_matrix = store_matrixs[0].size(); }
-                    if (store_multipliers.size() == store_matrixs.size() && cols_temp_matrix>0) // nuzzles==nuzzles
+                    if (!phys_matrixs.empty()) { cols_temp_matrix = phys_matrixs[0].size(); }
+                    if (store_multipliers.size() == phys_matrixs.size() && cols_temp_matrix>0) // nuzzles==nuzzles
                     {
                         for (size_t idx = 0; idx < store_multipliers.size(); ++idx) {
                             double m_max_flush_volume_t = (double)m_max_flush_volume, m_store_multipliers=store_multipliers[idx];
-                            std::transform(store_matrixs[idx].begin(), store_matrixs[idx].end(),
-                                           store_matrixs[idx].begin(),
+                            std::transform(phys_matrixs[idx].begin(), phys_matrixs[idx].end(),
+                                           phys_matrixs[idx].begin(),
                                            [m_max_flush_volume_t, m_store_multipliers](double inputx) {
                                                return std::clamp(inputx, 0.0, m_max_flush_volume_t / m_store_multipliers);
                                            });
                         }
                     }
                 }
+                // Expand physical sub-matrices back to full total×total,
+                // preserving the mixed-slot rows/cols from the snapshot taken
+                // in BuildTableObjStr.
+                const size_t num_phys = static_cast<size_t>(wxGetApp().filaments_cnt());
+                std::vector<std::vector<double>> store_matrixs;
+                for (size_t idx = 0; idx < phys_matrixs.size(); ++idx) {
+                    if (idx < m_raw_matrixs.size() && !m_raw_matrixs[idx].empty()) {
+                        const size_t total = static_cast<size_t>(
+                            std::round(std::sqrt(static_cast<double>(m_raw_matrixs[idx].size()))));
+                        store_matrixs.emplace_back(
+                            expand_physical_to_full_matrix(phys_matrixs[idx], m_raw_matrixs[idx], total, num_phys));
+                    } else {
+                        store_matrixs.emplace_back(phys_matrixs[idx]);
+                    }
+                }
                 this->StoreFlushData(extruder_num, store_matrixs, store_multipliers);
                 m_submit_flag = true;
                 this->Close();

src/slic3r/GUI/wxExtensions.cpp

@@ -783,6 +783,24 @@ void apply_extruder_selector(Slic3r::GUI::BitmapComboBox** ctrl,
                              bool use_thin_icon/* = false*/)
 {
     std::vector<wxBitmap*> icons = get_extruder_color_icons(use_thin_icon);
+    if (dynamic_cast<Slic3r::GUI::ObjectList*>(parent) != nullptr && Slic3r::GUI::wxGetApp().plater() != nullptr) {
+        const std::vector<std::string> all_colors =
+            Slic3r::GUI::wxGetApp().plater()->get_extruder_colors_from_plater_config(nullptr, true);
+
+        if (all_colors.size() > icons.size()) {
+            const double em = Slic3r::GUI::wxGetApp().em_unit();
+            const int    icon_width  = int((use_thin_icon ? 2.0 : 4.4) * em + 0.5);
+            const int    icon_height = int(2.0 * em + 0.5);
+            for (size_t idx = icons.size(); idx < all_colors.size(); ++idx) {
+                if (all_colors[idx].empty()) {
+                    icons.push_back(nullptr);
+                    continue;
+                }
+
+                icons.push_back(get_extruder_color_icon(all_colors[idx], std::to_string(idx + 1), icon_width, icon_height));
+            }
+        }
+    }
 
     if (!*ctrl) {
         *ctrl = new Slic3r::GUI::BitmapComboBox(parent, wxID_ANY, wxEmptyString, pos, size, 0, nullptr, wxCB_READONLY);
@@ -811,13 +829,13 @@ void apply_extruder_selector(Slic3r::GUI::BitmapComboBox** ctrl,
     for (wxBitmap* bmp : icons) {
         if (i == 0) {
             if (!first_item.empty())
-                (*ctrl)->Append(_(first_item), *bmp);
+                (*ctrl)->Append(_(first_item), bmp ? *bmp : wxNullBitmap);
             ++i;
         }
 
         (*ctrl)->Append(use_full_item_name
                         ? Slic3r::GUI::from_u8((boost::format("%1% %2%") % str % i).str())
-                        : wxString::Format("%d", i), *bmp);
+                        : wxString::Format("%d", i), bmp ? *bmp : wxNullBitmap);
         ++i;
     }
     (*ctrl)->SetSelection(0);

tests/fff_print/CMakeLists.txt

@@ -8,6 +8,7 @@ add_executable(${_TEST_NAME}_tests
 	test_flow.cpp
 	test_gcode.cpp
 	test_gcodewriter.cpp
+	test_mixed_filament_e2e.cpp
 	test_model.cpp
 	test_print.cpp
 	test_printgcode.cpp

tests/fff_print/test_mixed_filament_e2e.cpp

@@ -0,0 +1,218 @@
+// Tests for mixed-filament project-config round-trip persistence.
+//
+// The full-3MF (store_bbs_3mf / load_bbs_3mf) round-trip requires a heavy
+// PlateDataPtrs + Model + PresetBundle setup that is not yet scaffolded in
+// fff_print tests.  We therefore exercise the *persistence layer* directly:
+//
+//   MixedFilamentManager::serialize_custom_entries()
+//     → stored in project_config["mixed_filament_definitions"]
+//     → PresetBundle::sync_mixed_filaments_to_config()   (mirrors store path)
+//     → PresetBundle::sync_mixed_filaments_from_config() (mirrors load path)
+//
+// This is the code path that bbs_3mf.cpp invokes when writing/reading the
+// project config block, so a regression here would break 3MF persistence.
+//
+// TODO: full-pipeline E2E slice test (T0/T1 in G-code, dithering_local_z_mode
+//       sublayer assertions) requires the full Print::process() scaffolding;
+//       defer to a follow-up once a minimal PrintObject fixture exists.
+
+#include <catch2/catch_all.hpp>
+
+#include "libslic3r/MixedFilament.hpp"
+#include "libslic3r/PresetBundle.hpp"
+
+#include <algorithm>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+using namespace Slic3r;
+
+// ---------------------------------------------------------------------------
+// Helper: build a two-filament PresetBundle with colours set.
+// ---------------------------------------------------------------------------
+namespace {
+
+static PresetBundle make_bundle_2(const std::string &col_a = "#FF0000",
+                                  const std::string &col_b = "#0000FF")
+{
+    PresetBundle bundle;
+    bundle.filament_presets = {"Default Filament", "Default Filament"};
+    bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values = {col_a, col_b};
+    return bundle;
+}
+
+} // anonymous namespace
+
+// ---------------------------------------------------------------------------
+// Test 1 — plain auto-generated round-trip
+//   Build bundle → sync to config string → reload in fresh bundle → compare
+// ---------------------------------------------------------------------------
+TEST_CASE("Mixed filament 3MF round-trip: auto-generated entries survive serialize/load cycle",
+          "[MixedFilamentRoundTrip]")
+{
+    PresetBundle origin = make_bundle_2();
+    origin.sync_mixed_filaments_from_config();
+
+    const auto &orig_mixed = origin.mixed_filaments.mixed_filaments();
+    REQUIRE(!orig_mixed.empty());
+
+    // Capture the stable_id and component IDs of the first enabled entry.
+    const MixedFilament *first = nullptr;
+    for (const auto &mf : orig_mixed) {
+        if (mf.enabled && !mf.deleted) { first = &mf; break; }
+    }
+    REQUIRE(first != nullptr);
+    const uint64_t     orig_stable_id   = first->stable_id;
+    const unsigned int orig_component_a = first->component_a;
+    const unsigned int orig_component_b = first->component_b;
+
+    // Sync to config (mirrors what store_bbs_3mf does).
+    origin.sync_mixed_filaments_to_config();
+    const std::string serialized = origin.project_config.opt_string("mixed_filament_definitions");
+    // Auto-generated entries are NOT stored in the custom definitions string —
+    // they are rebuilt by auto_generate() on load.  The string will be empty
+    // unless a custom entry was added.  We just verify the round-trip doesn't
+    // drop auto-generated rows on re-sync.
+
+    // Reload into a fresh bundle with the same colours.
+    PresetBundle loaded = make_bundle_2();
+    loaded.project_config.option<ConfigOptionString>("mixed_filament_definitions")->value = serialized;
+    loaded.sync_mixed_filaments_from_config();
+
+    const auto &load_mixed = loaded.mixed_filaments.mixed_filaments();
+    REQUIRE(load_mixed.size() == orig_mixed.size());
+
+    // Find the matching entry by component pair.
+    const MixedFilament *reloaded = nullptr;
+    for (const auto &mf : load_mixed) {
+        if (mf.component_a == orig_component_a && mf.component_b == orig_component_b) {
+            reloaded = &mf;
+            break;
+        }
+    }
+    REQUIRE(reloaded != nullptr);
+    CHECK(reloaded->stable_id == orig_stable_id);
+}
+
+// ---------------------------------------------------------------------------
+// Test 2 — custom entry round-trip
+//   2 physical + 1 custom mixed entry: ratio_a, ratio_b, mix_b_percent, stable_id
+// ---------------------------------------------------------------------------
+TEST_CASE("Mixed filament 3MF round-trip: custom entry count, components, ratio, stable_id",
+          "[MixedFilamentRoundTrip]")
+{
+    const std::vector<std::string> colors = {"#FF0000", "#00FF00"};
+
+    MixedFilamentManager mgr;
+    // Add two custom entries to exercise the multi-entry path.
+    mgr.add_custom_filament(1, 2, 25, colors);
+    mgr.add_custom_filament(1, 2, 75, colors);
+
+    const auto &entries = mgr.mixed_filaments();
+    REQUIRE(entries.size() == 2);
+
+    const uint64_t stable_id_0 = entries[0].stable_id;
+    const uint64_t stable_id_1 = entries[1].stable_id;
+    CHECK(stable_id_0 != stable_id_1);
+
+    // Serialize and reload.
+    const std::string serialized = mgr.serialize_custom_entries();
+    REQUIRE(!serialized.empty());
+
+    MixedFilamentManager loaded;
+    loaded.load_custom_entries(serialized, colors);
+
+    const auto &reloaded = loaded.mixed_filaments();
+    REQUIRE(reloaded.size() == 2);
+
+    // Order must be preserved.
+    CHECK(reloaded[0].component_a  == 1);
+    CHECK(reloaded[0].component_b  == 2);
+    CHECK(reloaded[0].mix_b_percent == 25);
+    CHECK(reloaded[0].stable_id    == stable_id_0);
+
+    CHECK(reloaded[1].component_a  == 1);
+    CHECK(reloaded[1].component_b  == 2);
+    CHECK(reloaded[1].mix_b_percent == 75);
+    CHECK(reloaded[1].stable_id    == stable_id_1);
+}
+
+// ---------------------------------------------------------------------------
+// Test 3 — PresetBundle project_config string path (mirrors 3MF store+load)
+//   Verify that sync_mixed_filaments_to_config + sync_mixed_filaments_from_config
+//   preserves a custom entry end-to-end through the project_config string.
+// ---------------------------------------------------------------------------
+TEST_CASE("Mixed filament 3MF round-trip: PresetBundle project_config string path",
+          "[MixedFilamentRoundTrip]")
+{
+    PresetBundle origin = make_bundle_2("#FFFF00", "#FF00FF");
+    origin.sync_mixed_filaments_from_config();
+
+    // Add a custom entry on top of auto-generated ones.
+    const auto &colors = origin.project_config.option<ConfigOptionStrings>("filament_colour")->values;
+    origin.mixed_filaments.add_custom_filament(1, 2, 40, colors);
+
+    const size_t num_entries_before = origin.mixed_filaments.mixed_filaments().size();
+
+    // Count custom entries in origin.
+    size_t custom_count_before = 0;
+    uint64_t custom_stable_id = 0;
+    for (const auto &mf : origin.mixed_filaments.mixed_filaments()) {
+        if (mf.custom && mf.enabled && !mf.deleted) {
+            ++custom_count_before;
+            custom_stable_id = mf.stable_id;
+        }
+    }
+    REQUIRE(custom_count_before == 1);
+
+    // Sync to config string — mirrors bbs_3mf store path.
+    origin.sync_mixed_filaments_to_config();
+    const std::string defs = origin.project_config.opt_string("mixed_filament_definitions");
+    REQUIRE(!defs.empty());
+
+    // Reload — mirrors bbs_3mf load path.
+    PresetBundle loaded = make_bundle_2("#FFFF00", "#FF00FF");
+    loaded.project_config.option<ConfigOptionString>("mixed_filament_definitions")->value = defs;
+    loaded.sync_mixed_filaments_from_config();
+
+    const auto &reloaded = loaded.mixed_filaments.mixed_filaments();
+    REQUIRE(reloaded.size() == num_entries_before);
+
+    // Custom entry must survive with its stable_id intact.
+    size_t custom_count_after = 0;
+    uint64_t reloaded_stable_id = 0;
+    for (const auto &mf : reloaded) {
+        if (mf.custom && mf.enabled && !mf.deleted) {
+            ++custom_count_after;
+            reloaded_stable_id = mf.stable_id;
+        }
+    }
+    CHECK(custom_count_after == custom_count_before);
+    CHECK(reloaded_stable_id == custom_stable_id);
+}
+
+// ---------------------------------------------------------------------------
+// Test 4 — total_filaments counts physical + mixed correctly after round-trip
+// ---------------------------------------------------------------------------
+TEST_CASE("Mixed filament 3MF round-trip: total_filaments count is stable after reload",
+          "[MixedFilamentRoundTrip]")
+{
+    PresetBundle origin = make_bundle_2();
+    origin.sync_mixed_filaments_from_config();
+
+    const size_t num_physical = origin.filament_presets.size();
+    const size_t total_before = origin.mixed_filaments.total_filaments(num_physical);
+    // For 2 physical filaments C(2,2)=1 virtual → total must be 3.
+    REQUIRE(total_before == 3u);
+
+    origin.sync_mixed_filaments_to_config();
+    const std::string defs = origin.project_config.opt_string("mixed_filament_definitions");
+
+    PresetBundle loaded = make_bundle_2();
+    loaded.project_config.option<ConfigOptionString>("mixed_filament_definitions")->value = defs;
+    loaded.sync_mixed_filaments_from_config();
+
+    const size_t total_after = loaded.mixed_filaments.total_filaments(loaded.filament_presets.size());
+    CHECK(total_after == total_before);
+}

tests/libslic3r/CMakeLists.txt

@@ -16,6 +16,8 @@ add_executable(${_TEST_NAME}_tests
     test_polygon.cpp
     test_mutable_polygon.cpp
     test_mutable_priority_queue.cpp
+    test_mixed_filament.cpp
+    test_review_fixes.cpp
     test_stl.cpp
     test_meshboolean.cpp
     test_marchingsquares.cpp

tests/libslic3r/test_review_fixes.cpp

@@ -0,0 +1,189 @@
+#include <catch2/catch_all.hpp>
+
+#include "libslic3r/MixedFilament.hpp"
+#include "libslic3r/Print.hpp"
+#include "libslic3r/PrintConfig.hpp"
+#include "libslic3r/Model.hpp"
+#include "libslic3r/Slicing.hpp"
+
+#include <boost/filesystem.hpp>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+using namespace Slic3r;
+
+// Finding 1 — the helper computing max supported filament ID after a 3MF
+// project-config load must include enabled mixed rows.
+TEST_CASE("[review-fixes] mixed-aware max filament id", "[review-fixes]")
+{
+    MixedFilamentManager mgr;
+    const size_t physical_count = 3;
+    const std::vector<std::string> colors = {"#FF0000", "#00FF00", "#0000FF"};
+
+    // No mixed rows: max == physical.
+    REQUIRE(mgr.total_filaments(physical_count) == physical_count);
+
+    // Add an enabled mixed row spanning physical 1 + 2 (custom + enabled by default).
+    mgr.add_custom_filament(1u, 2u, 50, colors);
+    REQUIRE(mgr.mixed_filaments().size() == 1);
+    REQUIRE(mgr.total_filaments(physical_count) == physical_count + 1);
+
+    // A disabled row does not contribute.
+    mgr.add_custom_filament(1u, 2u, 25, colors);
+    REQUIRE(mgr.mixed_filaments().size() == 2);
+    mgr.mixed_filaments().back().enabled = false;
+    REQUIRE(mgr.total_filaments(physical_count) == physical_count + 1);
+
+    // A deleted row also does not contribute (enabled_count() filters deleted).
+    mgr.add_custom_filament(2u, 3u, 50, colors);
+    REQUIRE(mgr.mixed_filaments().size() == 3);
+    mgr.mixed_filaments().back().deleted = true;
+    mgr.mixed_filaments().back().enabled = false;
+    REQUIRE(mgr.total_filaments(physical_count) == physical_count + 1);
+}
+
+// Finding 2 — passing nullptr for the print object must keep the legacy
+// behaviour: no mixed gradient or dithering ranges are applied, and the
+// profile is still seeded from the slicing parameters.
+TEST_CASE("[review-fixes] update_layer_height_profile passthrough without print object",
+          "[review-fixes]")
+{
+    Model model;
+    ModelObject *mo = model.add_object();
+    REQUIRE(mo != nullptr);
+
+    SlicingParameters sp;
+    sp.layer_height = 0.2;
+    sp.first_object_layer_height = 0.2;
+    sp.object_print_z_min = 0.0;
+    sp.object_print_z_uncompensated_max = 10.0;
+
+    std::vector<coordf_t> profile;
+    const bool updated = PrintObject::update_layer_height_profile(*mo, sp, profile, nullptr);
+    REQUIRE(updated);
+    REQUIRE(!profile.empty());
+
+    // Strong check: the nullptr branch must be a passthrough to
+    // layer_height_profile_from_ranges with the model_object's own
+    // layer_config_ranges — i.e. no mixed-gradient or dithering overrides
+    // were applied. Computing the expected profile via the same call the
+    // function performs internally lets a regression that silently sneaks
+    // those overrides into the nullptr path fail this test.
+    const std::vector<coordf_t> expected =
+        Slic3r::layer_height_profile_from_ranges(sp, mo->layer_config_ranges);
+    REQUIRE(profile == expected);
+}
+
+// Finding 4 — ToolOrdering used to push raw 1-based virtual mixed-filament IDs
+// directly onto layer_tools.extruders, which then got decremented as if they
+// were physical extruder IDs. The fix routes those IDs through the
+// MixedFilamentManager so that virtual IDs collapse to a real physical extruder
+// while physical IDs pass through unchanged.
+TEST_CASE("[review-fixes] resolve_mixed_1based passthrough on physical id",
+          "[review-fixes]")
+{
+    MixedFilamentManager mgr;
+    const std::vector<std::string> colors = {"#FF0000", "#00FF00"};
+    // Add a custom mixed row spanning physical 1 + 2.
+    mgr.add_custom_filament(1u, 2u, 50, colors);
+    REQUIRE(mgr.mixed_filaments().size() == 1);
+
+    const size_t num_physical = colors.size();
+
+    // Physical id (1) must passthrough.
+    REQUIRE(mgr.resolve(1u, num_physical, /*layer_index=*/0, /*print_z=*/0.f, /*layer_height=*/0.2f) == 1u);
+    REQUIRE(mgr.resolve(2u, num_physical, /*layer_index=*/0, /*print_z=*/0.f, /*layer_height=*/0.2f) == 2u);
+
+    // Virtual id (3 = 2 physical + 1 mixed) must resolve to 1 or 2 depending on cadence.
+    const unsigned int resolved = mgr.resolve(3u, num_physical, 0, 0.f, 0.2f);
+    REQUIRE((resolved == 1u || resolved == 2u));
+}
+
+TEST_CASE("[review-fixes] mixed/dithering option keys exist in PrintConfig",
+          "[review-fixes]")
+{
+    // Sanity guard for finding 6: any key the porter wires into invalidation
+    // must resolve in the config. Build a default-populated DynamicPrintConfig
+    // that contains every print_config_def key, then probe the option lookup.
+    static const std::vector<std::string> keys = {
+        "mixed_filament_definitions",
+        "mixed_filament_gradient_mode",
+        "mixed_filament_height_lower_bound",
+        "mixed_filament_height_upper_bound",
+        "mixed_filament_advanced_dithering",
+        "mixed_filament_component_bias_enabled",
+        "mixed_filament_surface_indentation",
+        "mixed_filament_region_collapse",
+        "dithering_z_step_size",
+        "dithering_local_z_mode",
+        "dithering_local_z_whole_objects",
+        "dithering_local_z_direct_multicolor",
+        "dithering_step_painted_zones_only",
+    };
+
+    std::unique_ptr<DynamicPrintConfig> cfg(DynamicPrintConfig::new_from_defaults_keys(keys));
+    REQUIRE(cfg != nullptr);
+
+    for (const std::string &k : keys) {
+        INFO("missing config key: " << k);
+        REQUIRE(cfg->option(k) != nullptr);
+        // And the canonical print_config_def must know about it.
+        REQUIRE(print_config_def.get(k) != nullptr);
+    }
+}
+
+TEST_CASE("[review-fixes] clear_local_z_plan called from clear_layers", "[review-fixes][mixed-filament]")
+{
+    // Sentinel: ensure the source contains the 3 invalidation hooks the
+    // FullSpectrum verification report flagged as missing. This is a
+    // smoke-test against the source so we can detect future regressions
+    // without depending on a full slicing-pipeline harness.
+    namespace fs = boost::filesystem;
+    const fs::path repo = fs::path(__FILE__).parent_path().parent_path().parent_path();
+    const fs::path src  = repo / "src" / "libslic3r" / "PrintObject.cpp";
+    REQUIRE(fs::exists(src));
+
+    std::ifstream in(src.string());
+    std::stringstream buf; buf << in.rdbuf();
+    const std::string body = buf.str();
+
+    const auto count_substr = [&](const std::string &needle) {
+        size_t n = 0, pos = 0;
+        while ((pos = body.find(needle, pos)) != std::string::npos) { ++n; ++pos; }
+        return n;
+    };
+
+    // Three FS-mandated call sites: clear_layers, invalidate_step(posSlice),
+    // invalidate_all_steps. Plus the one already-present site inside
+    // build_local_z_plan(). PrintObject.cpp itself has 3 (4 once the
+    // backport is complete).
+    REQUIRE(count_substr("this->clear_local_z_plan()") >= 3);
+}
+
+TEST_CASE("[review-fixes] merge_segmented_layers preserves channel 0", "[review-fixes][mixed-filament]")
+{
+    // Sentinel: ensure merge_segmented_layers uses the FS shape
+    // (output sized num_facets_states, channel 0 = default), not the
+    // pre-FS-a11b70e3a shape (output sized num_facets_states - 1,
+    // channel 0 dropped). The FS-verbatim apply_mm_segmentation in
+    // PrintObjectSlice.cpp expects channel 0 to be present; mismatching
+    // shapes silently shifts every painted region's filament_id by -1
+    // (e.g. paint with mixed slot 4 -> applied as physical filament 3).
+    namespace fs = boost::filesystem;
+    const fs::path repo = fs::path(__FILE__).parent_path().parent_path().parent_path();
+    const fs::path src  = repo / "src" / "libslic3r" / "MultiMaterialSegmentation.cpp";
+    REQUIRE(fs::exists(src));
+
+    std::ifstream in(src.string());
+    std::stringstream buf; buf << in.rdbuf();
+    const std::string body = buf.str();
+
+    // Producer must NOT subtract one from num_facets_states when sizing the output.
+    REQUIRE(body.find("num_facets_states - 1") == std::string::npos);
+    // Producer must NOT shift indexing back by one when writing into the output.
+    REQUIRE(body.find("[extruder_id - 1]") == std::string::npos);
+    // Loop must include channel 0 (extruder_id starts at 0, not 1).
+    REQUIRE(body.find("for (size_t extruder_id = 0; extruder_id < num_facets_states") != std::string::npos);
+}