Purge tower part 1

result.json

@@ -0,0 +1,10 @@
+{
+	"error_string": "Success.",
+	"export_time": 0,
+	"layer_height": 0.0,
+	"plate_index": 0,
+	"prepare_time": 0,
+	"return_code": 0,
+	"sparse_infill_density": 0.0,
+	"wall_loops": 0
+}

src/libslic3r/GCode/ToolOrdering.cpp

@@ -381,6 +381,10 @@ bool ToolOrdering::insert_wipe_tower_extruder()
 {
     if (!m_print_config_ptr || !m_print_config_ptr->enable_prime_tower)
         return false;
+    // Belt mode has no classic wipe tower; the dedicated wipe tower filament
+    // must not inject extra toolchanges into the purge prism planning.
+    if (m_print_config_ptr->belt_printer)
+        return false;
     if (m_print_config_ptr->wipe_tower_filament == 0)
         return false;
 

src/libslic3r/Preset.cpp

@@ -1160,6 +1160,8 @@ static std::vector<std::string> s_Preset_print_options{
     "prime_volume",
     "prime_tower_infill_gap",
     "prime_tower_flat_ironing",
+    "belt_purge_tower_width",
+    "belt_purge_tower_object",
     "enable_tower_interface_features",
     "enable_tower_interface_cooldown_during_tower",
     "wipe_tower_no_sparse_layers",

src/libslic3r/Print.cpp

@@ -22,6 +22,7 @@
 #include "MaterialType.hpp"
 #include "Model.hpp"
 #include "format.hpp"
+#include "LocalesUtils.hpp"
 #include <float.h>
 
 #include <algorithm>
@@ -389,6 +390,7 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
             || opt_key == "prime_volume"
             || opt_key == "flush_into_infill"
             || opt_key == "flush_into_support"
+            || opt_key == "belt_purge_tower_width"
             || opt_key == "initial_layer_infill_speed"
             || opt_key == "travel_speed"
             || opt_key == "travel_speed_z"
@@ -1473,6 +1475,15 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
     }
 
     if (m_config.enable_prime_tower) {
+        if (m_config.belt_printer.value && m_config.print_sequence == PrintSequence::ByObject
+            && extruders.size() > 1 && warning != nullptr) {
+            StringObjectException warningtemp;
+            warningtemp.string     = L("The belt purge tower is not generated in \"By object\" print sequence; "
+                                       "filament changes will not be purged.");
+            warningtemp.opt_key    = "enable_prime_tower";
+            warningtemp.is_warning = true;
+            *warning               = warningtemp;
+        }
         for (const PrintObject* object : m_objects) {
             if (object->config().precise_z_height.value) {
                 warn(L("Enabling both precise Z height and the prime tower may cause slicing errors."), "precise_z_height");
@@ -1596,7 +1607,7 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
                     return {_u8L("Variable layer height is not supported with Organic supports.") };
         }
 
-    if (this->has_wipe_tower() && ! m_objects.empty()) {
+    if ((this->has_wipe_tower() || this->has_belt_purge_tower()) && ! m_objects.empty()) {
         // Make sure all extruders use same diameter filament and have the same nozzle diameter
         // EPSILON comparison is used for nozzles and 10 % tolerance is used for filaments
         double first_nozzle_diam = m_config.nozzle_diameter.get_at(extruders.front());
@@ -1612,12 +1623,17 @@ StringObjectException Print::validate(std::vector<StringObjectException> *warnin
                 }
         }
 
-        if (! m_config.use_relative_e_distances)
+        // The following two constraints come from the classic wipe tower G-code
-            return { L("The Wipe Tower is currently only supported with the relative extruder addressing (use_relative_e_distances=1).") };
+        // generator; purging into the belt purge prism uses normal object
+        // extrusions and does not need them.
+        if (this->has_wipe_tower()) {
+            if (! m_config.use_relative_e_distances)
+                return { L("The Wipe Tower is currently only supported with the relative extruder addressing (use_relative_e_distances=1).") };
+
+            if (m_config.ooze_prevention && m_config.single_extruder_multi_material)
+                return {L("Ooze prevention is only supported with the wipe tower when 'single_extruder_multi_material' is off.")};
+        }
 
-        if (m_config.ooze_prevention && m_config.single_extruder_multi_material)
-            return {L("Ooze prevention is only supported with the wipe tower when 'single_extruder_multi_material' is off.")};
-            
 #if 0
         if (m_config.gcode_flavor != gcfRepRapSprinter && m_config.gcode_flavor != gcfRepRapFirmware &&
             m_config.gcode_flavor != gcfRepetier && m_config.gcode_flavor != gcfMarlinLegacy && m_config.gcode_flavor != gcfMarlinFirmware)
@@ -2708,7 +2724,10 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
 
         m_wipe_tower_data.clear();
         m_tool_ordering.clear();
-        if (this->has_wipe_tower()) {
+        if (this->has_belt_purge_tower() && this->config().print_sequence != PrintSequence::ByObject) {
+            this->_plan_belt_purge();
+        }
+        else if (this->has_wipe_tower()) {
             this->_make_wipe_tower();
         }
         else if (this->config().print_sequence != PrintSequence::ByObject) {
@@ -4085,6 +4104,13 @@ int Print::get_config_index(int filament_id, int layer_id, const std::vector<std
 // Wipe tower support.
 bool Print::has_wipe_tower() const
 {
+    // Belt printers never get the classic wipe tower: its G-code is generated
+    // directly in machine XY coordinates and bypasses the belt rotation
+    // transform. Purging is routed into the belt purge prism instead
+    // (see has_belt_purge_tower() / _plan_belt_purge()).
+    if (m_config.belt_printer.value)
+        return false;
+
     if (m_config.enable_prime_tower.value == true) {
         if (m_config.enable_wrapping_detection.value && m_config.wrapping_exclude_area.values.size() > 2)
             return true;
@@ -4097,6 +4123,16 @@ bool Print::has_wipe_tower() const
     return false;
 }
 
+// Belt purge prism: purging after filament changes is routed into a sliced
+// prism object via the flush-into-objects machinery instead of a wipe tower.
+bool Print::has_belt_purge_tower() const
+{
+    return m_config.belt_printer.value
+        && m_config.enable_prime_tower.value
+        && !m_config.spiral_mode.value
+        && m_config.filament_diameter.values.size() > 1;
+}
+
 const WipeTowerData &Print::wipe_tower_data(size_t filaments_cnt) const
 {
     // If the wipe tower wasn't created yet, make sure the depth and brim_width members are set to default.
@@ -4183,6 +4219,179 @@ bool Print::enable_timelapse_print() const
     return m_config.timelapse_type.value == TimelapseType::tlSmooth;
 }
 
+// Belt mode: snap the purge prism's layer grid onto the printed objects' grid.
+// After belt slicing every object's layer print_z carries a per-object global
+// z offset (mesh-vertex-scan belt_z_shift + instance-Y-dependent terms), so
+// objects at different belt-Y positions do not share a layer grid. Purge
+// marking looks absorbers up with get_layer_at_printz(lt.print_z, EPSILON),
+// so the prism only absorbs purge at toolchange print_z values that coincide
+// with one of its own layers. Shifting the prism by at most half a layer
+// (a sub-layer-height displacement along the belt) makes its grid residue
+// match the reference object's; both grids step by the same layer height
+// (enforced by validate()), so matching residues means exact layer matches.
+void Print::_align_belt_purge_layers()
+{
+    PrintObject *prism = nullptr;
+    for (PrintObject *po : m_objects)
+        if (po->config().belt_purge_tower_object.value) {
+            prism = po;
+            break;
+        }
+    if (prism == nullptr || prism->layers().empty())
+        return;
+
+    const double h = prism->config().layer_height.value;
+    if (h <= EPSILON)
+        return;
+
+    // Grid residue of an object's layer grid: identical for all of an object's
+    // layers above the first since they step by h.
+    auto grid_offset = [h](const PrintObject *po) {
+        const double z = po->layers().front()->print_z;
+        return z - std::floor(z / h) * h; // in [0, h)
+    };
+
+    // Reference grid: the tallest non-prism object (proxy for the object with
+    // the most toolchange layers).
+    const PrintObject *ref     = nullptr;
+    double             ref_top = -std::numeric_limits<double>::max();
+    for (const PrintObject *po : m_objects) {
+        if (po->config().belt_purge_tower_object.value || po->layers().empty())
+            continue;
+        const double top = po->layers().back()->print_z;
+        if (top > ref_top) {
+            ref_top = top;
+            ref     = po;
+        }
+    }
+    if (ref == nullptr)
+        return;
+
+    const double ref_offset     = grid_offset(ref);
+    bool         grids_mismatch = false;
+    for (const PrintObject *po : m_objects) {
+        if (po == ref || po->config().belt_purge_tower_object.value || po->layers().empty())
+            continue;
+        double d = std::abs(grid_offset(po) - ref_offset);
+        d        = std::min(d, h - d);
+        if (d > 5. * EPSILON) {
+            grids_mismatch = true;
+            break;
+        }
+    }
+
+    // Shift normalized to (-h/2, h/2].
+    double delta = ref_offset - grid_offset(prism);
+    if (delta > 0.5 * h)
+        delta -= h;
+    else if (delta <= -0.5 * h)
+        delta += h;
+
+    BOOST_LOG_TRIVIAL(debug) << "[BELT-DEBUG] purge prism grid snap"
+        << " ref=" << ref->model_object()->name
+        << " ref_offset=" << ref_offset
+        << " prism_offset=" << grid_offset(prism)
+        << " delta=" << delta
+        << " grids_mismatch=" << grids_mismatch;
+
+    prism->belt_shift_layer_grid(delta);
+
+    if (grids_mismatch)
+        this->active_step_add_warning(
+            PrintStateBase::WarningLevel::NON_CRITICAL,
+            _u8L("Objects on the plate are sliced on different layer grids; the belt purge tower can only follow "
+                 "one of them. Filament changes on layers of the other objects may not be fully purged."));
+}
+
+// Belt mode replacement for _make_wipe_tower(): plan filament-change purging
+// into the belt purge prism (and any other flush_into_* object) using the
+// flush-into-objects machinery, without generating classic wipe tower G-code.
+// The toolchange itself is emitted by GCode::set_extruder() via the
+// change_filament_gcode macro; the overrides marked here make the new
+// filament's first extrusions land in the purge prism.
+void Print::_plan_belt_purge()
+{
+    m_wipe_tower_data.clear();
+
+    // Must run before ToolOrdering is built: LayerTools merge per-object layer
+    // print_z values, and the prism only absorbs purge where its (snapped)
+    // layers coincide with the toolchange layers.
+    this->_align_belt_purge_layers();
+
+    const unsigned int number_of_extruders = (unsigned int) m_config.filament_colour.values.size();
+
+    // No initial priming extrusions: there is no tower to prime on.
+    m_wipe_tower_data.tool_ordering = ToolOrdering(*this, (unsigned int) -1, false);
+    m_wipe_tower_data.tool_ordering.sort_and_build_data(*this, (unsigned int) -1, false);
+
+    if (m_wipe_tower_data.tool_ordering.empty() || m_wipe_tower_data.tool_ordering.last_extruder() == unsigned(-1))
+        throw Slic3r::SlicingError("The print is empty. The model is not printable with current print settings.");
+
+    if (!m_wipe_tower_data.tool_ordering.has_wipe_tower())
+        // No toolchanges anywhere, nothing to purge.
+        return;
+
+    this->throw_if_canceled();
+
+    // Flush volumes per filament pair, mirroring the generic wipe tower path:
+    // full flush matrix for single extruder multi material with purging enabled,
+    // plain prime volume otherwise.
+    std::vector<float> flush_matrix(cast<float>(
+        get_flush_volumes_matrix(m_config.flush_volumes_matrix.values, 0, m_config.nozzle_diameter.values.size())));
+    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));
+    const bool  use_flush_matrix = m_config.purge_in_prime_tower && m_config.single_extruder_multi_material;
+    const float flush_multiplier = (float) m_config.flush_multiplier.get_at(0);
+
+    float  total_leftover      = 0.f;
+    float  worst_layer_leftover = 0.f;
+    double worst_layer_z       = 0.;
+
+    unsigned int current_extruder_id = m_wipe_tower_data.tool_ordering.first_extruder();
+    for (auto &layer_tools : m_wipe_tower_data.tool_ordering.layer_tools()) {
+        float layer_leftover = 0.f;
+        for (const unsigned int extruder_id : layer_tools.extruders) {
+            if (extruder_id == current_extruder_id)
+                continue;
+            float volume_to_wipe = use_flush_matrix ?
+                wipe_volumes[current_extruder_id][extruder_id] * flush_multiplier :
+                (float) m_config.prime_volume;
+            float leftover = layer_tools.wiping_extrusions().mark_wiping_extrusions(*this, current_extruder_id, extruder_id,
+                                                                                    volume_to_wipe);
+            BOOST_LOG_TRIVIAL(trace) << "[BELT-DEBUG] purge toolchange print_z=" << layer_tools.print_z
+                << " filament " << current_extruder_id << "->" << extruder_id
+                << " requested=" << volume_to_wipe
+                << " absorbed=" << volume_to_wipe - leftover
+                << " leftover=" << leftover;
+            layer_leftover += leftover;
+            current_extruder_id = extruder_id;
+        }
+        layer_tools.wiping_extrusions().ensure_perimeters_infills_order(*this);
+        if (layer_leftover > 0.f) {
+            total_leftover += layer_leftover;
+            if (layer_leftover > worst_layer_leftover) {
+                worst_layer_leftover = layer_leftover;
+                worst_layer_z        = layer_tools.print_z;
+            }
+        }
+        this->throw_if_canceled();
+    }
+
+    if (total_leftover > 1.f) {
+        this->active_step_add_warning(
+            PrintStateBase::WarningLevel::CRITICAL,
+            Slic3r::format(_u8L("The belt purge tower cannot absorb the full purge volume: %1% mm³ in total could not "
+                                "be purged (worst layer: %2% mm³ at height %3%). The print may show color bleeding. "
+                                "Increase the belt purge tower width, or reduce flushing volumes."),
+                           int(std::ceil(total_leftover)), int(std::ceil(worst_layer_leftover)),
+                           Slic3r::float_to_string_decimal_point(worst_layer_z, 2)));
+        BOOST_LOG_TRIVIAL(warning) << "[BELT-DEBUG] purge planning leftover total=" << total_leftover
+            << " worst_layer=" << worst_layer_leftover << " at print_z=" << worst_layer_z;
+    }
+}
+
 void Print::_make_wipe_tower()
 {
     m_wipe_tower_data.clear();

src/libslic3r/Print.hpp

@@ -558,6 +558,10 @@ private:
     std::vector<std::set<int>> detect_extruder_geometric_unprintables() const;
 
     void slice_volumes();
+    // Belt mode: shift the sliced layer grid (layer print_z and the belt floor
+    // clipping shift) by delta, used by Print::_align_belt_purge_layers() to
+    // snap the purge prism's layers onto the printed objects' layer grid.
+    void belt_shift_layer_grid(double delta);
     //BBS
     ExPolygons _shrink_contour_holes(double contour_delta, double hole_delta, const ExPolygons& polys) const;
     // BBS
@@ -1085,6 +1089,8 @@ public:
 
     // Wipe tower support.
     bool                        has_wipe_tower() const;
+    // Belt purge prism (belt-mode replacement for the wipe tower).
+    bool                        has_belt_purge_tower() const;
     const WipeTowerData&        wipe_tower_data(size_t filaments_cnt = 0) const;
     const ToolOrdering& 		tool_ordering() const { return m_tool_ordering; }
 
@@ -1330,6 +1336,12 @@ private:
 
     void                _make_skirt();
     void                _make_wipe_tower();
+    // Belt mode: route filament-change purging into the belt purge prism
+    // (flush-into-objects) without generating a classic wipe tower.
+    void                _plan_belt_purge();
+    // Belt mode: shift the purge prism's layer grid to match the printed
+    // objects' grid so toolchange layers find prism layers to purge into.
+    void                _align_belt_purge_layers();
     void                finalize_first_layer_convex_hull();
     void                update_filament_self_index_cache();
     // Deduplicates, per filament, the (extruder type x volume type) variants the grouping

src/libslic3r/PrintConfig.cpp

@@ -7321,6 +7321,20 @@ void PrintConfigDef::init_fff_params()
         def->set_default_value(new ConfigOptionEnum<BeltSupportZOffsetMode>(BeltSupportZOffsetMode::Unconditional));
     }
 
+    def = this->add("belt_purge_tower_width", coFloat);
+    def->label = L("Belt purge tower width");
+    def->category = L("Printable space");
+    def->tooltip = L("Width (machine X, across the belt) of the purge prism that is automatically "
+                     "generated on belt printers when the prime tower is enabled and multiple "
+                     "filaments are used. Filament-change purging is routed into this prism's "
+                     "extrusions instead of a classic wipe tower. Its height is computed "
+                     "automatically from the worst-case purge volume per layer: a wider prism "
+                     "results in a shorter one.");
+    def->sidetext = L("mm");
+    def->min = 1.;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(35.));
+
     def = this->add("tree_support_branch_angle", coFloat);
     def->label = L("Tree support branch angle");
     def->category = L("Support");
@@ -7966,6 +7980,16 @@ void PrintConfigDef::init_fff_params()
         "It will not take effect unless the prime tower is enabled.");
     def->set_default_value(new ConfigOptionBool(false));
 
+    // Internal marker (not shown in any settings tab): identifies the auto-generated
+    // belt purge prism so it can be updated/removed by the auto-manager and aligned
+    // to the object layer grid by the backend. Persisted to 3mf like any per-object key.
+    def = this->add("belt_purge_tower_object", coBool);
+    def->category = L("Flush options");
+    def->label = L("Belt purge tower object");
+    def->tooltip = L("Marks the auto-generated belt purge prism. Managed automatically; do not set manually.");
+    def->mode = comDevelop;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("wipe_tower_bridging", coFloat);
     def->label = L("Maximal bridging distance");
     def->tooltip = L("Maximal distance between supports on sparse infill sections.");

src/libslic3r/PrintConfig.hpp

@@ -1228,6 +1228,9 @@ PRINT_CONFIG_CLASS_DEFINE(
     // BBS
     ((ConfigOptionBool,                flush_into_infill))
     ((ConfigOptionBool,                flush_into_support))
+    // Marker for the auto-generated belt purge prism; identifies the object to
+    // the auto-manager (GUI) and the layer-grid alignment step (backend).
+    ((ConfigOptionBool,                belt_purge_tower_object))
     // BBS
     ((ConfigOptionFloat,              tree_support_branch_distance))
     ((ConfigOptionFloat,              tree_support_tip_diameter))
@@ -1802,6 +1805,8 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     ((ConfigOptionFloat,                          belt_support_floor_offset))
     ((ConfigOptionEnum<BeltSupportFloorMode>,     belt_support_floor_mode))
     ((ConfigOptionEnum<BeltSupportZOffsetMode>,   belt_support_z_offset_mode))
+    // Width (machine X, across the belt) of the auto-generated belt purge prism.
+    ((ConfigOptionFloat,                          belt_purge_tower_width))
     //BBS
     ((ConfigOptionInts,               additional_cooling_fan_speed))
     ((ConfigOptionInts,               close_additional_fan_first_x_layers))

src/libslic3r/PrintObject.cpp

@@ -1663,7 +1663,8 @@ bool PrintObject::invalidate_state_by_config_options(
         } else if (
                opt_key == "flush_into_infill"
             || opt_key == "flush_into_objects"
-            || opt_key == "flush_into_support") {
+            || opt_key == "flush_into_support"
+            || opt_key == "belt_purge_tower_object") {
             invalidated |= m_print->invalidate_step(psWipeTower);
             invalidated |= m_print->invalidate_step(psGCodeExport);
         } else {

src/libslic3r/PrintObjectSlice.cpp

@@ -1392,6 +1392,27 @@ void apply_fuzzy_skin_segmentation(PrintObject &print_object, ThrowOnCancel thro
     }); // end of parallel_for
 }
 
+// Belt mode: shift the sliced layer grid by delta. Mirrors the global_z_offset
+// application in slice() — layer print_z and belt_floor_z_shift move together
+// so belt floor clipping stays consistent with the shifted grid. Used by
+// Print::_align_belt_purge_layers() to snap the purge prism onto the printed
+// objects' layer grid; |delta| <= half a layer height, i.e. a sub-layer shift
+// of the prism along the belt.
+void PrintObject::belt_shift_layer_grid(double delta)
+{
+    if (std::abs(delta) < EPSILON)
+        return;
+    for (Layer *layer : m_layers)
+        layer->print_z += delta;
+    for (SupportLayer *layer : m_support_layers)
+        layer->print_z += delta;
+    m_slicing_params.belt_floor_z_shift += delta;
+    BOOST_LOG_TRIVIAL(trace) << "[BELT-DEBUG] belt_shift_layer_grid"
+        << " obj=" << this->model_object()->name
+        << " delta=" << delta
+        << " first_layer.print_z=" << (m_layers.empty() ? 0. : m_layers.front()->print_z);
+}
+
 // 1) Decides Z positions of the layers,
 // 2) Initializes layers and their regions
 // 3) Slices the object meshes

src/slic3r/GUI/ConfigManipulation.cpp

@@ -971,11 +971,16 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, in
     toggle_line("preheat_steps", have_ooze_prevention && (preheat_steps > 0));
 
     bool have_prime_tower = config->opt_bool("enable_prime_tower");
+    // ORCA-Belt: belt printers replace the classic wipe tower with the
+    // auto-generated belt purge prism — only its width is tunable; the
+    // classic tower geometry options do not apply. (is_belt_printer is
+    // computed at the top of this function.)
+    toggle_line("belt_purge_tower_width", have_prime_tower && is_belt_printer);
     for (auto el : {"prime_tower_width", "prime_tower_brim_width", "prime_tower_skip_points", "wipe_tower_wall_type", "prime_tower_infill_gap","prime_tower_enable_framework", "enable_tower_interface_features"})
-        toggle_line(el, have_prime_tower);
+        toggle_line(el, have_prime_tower && !is_belt_printer);
 
     toggle_line("enable_tower_interface_cooldown_during_tower",
-                have_prime_tower && config->opt_bool("enable_tower_interface_features"));
+                have_prime_tower && !is_belt_printer && config->opt_bool("enable_tower_interface_features"));
 
     bool purge_in_primetower = preset_bundle->printers.get_edited_preset().config.opt_bool("purge_in_prime_tower");
 
@@ -983,17 +988,17 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, in
                     "wipe_tower_extra_spacing", "wipe_tower_max_purge_speed",
                     "wipe_tower_bridging", "wipe_tower_extra_flow",
                     "wipe_tower_no_sparse_layers"})
-            toggle_line(el, have_prime_tower && supports_wipe_tower_2);
+            toggle_line(el, have_prime_tower && supports_wipe_tower_2 && !is_belt_printer);
 
     WipeTowerWallType wipe_tower_wall_type = config->opt_enum<WipeTowerWallType>("wipe_tower_wall_type");
-    bool have_rib_wall = (wipe_tower_wall_type == WipeTowerWallType::wtwRib)&&have_prime_tower;
+    bool have_rib_wall = (wipe_tower_wall_type == WipeTowerWallType::wtwRib)&&have_prime_tower&&!is_belt_printer;
-    toggle_line("wipe_tower_cone_angle", have_prime_tower && supports_wipe_tower_2 && wipe_tower_wall_type == WipeTowerWallType::wtwCone);
+    toggle_line("wipe_tower_cone_angle", have_prime_tower && supports_wipe_tower_2 && !is_belt_printer && wipe_tower_wall_type == WipeTowerWallType::wtwCone);
     toggle_line("wipe_tower_extra_rib_length", have_rib_wall);
     toggle_line("wipe_tower_rib_width", have_rib_wall);
     toggle_line("wipe_tower_fillet_wall", have_rib_wall);
     toggle_field("prime_tower_width", have_prime_tower && !have_rib_wall);
 
-    toggle_line("single_extruder_multi_material_priming", !bSEMM && have_prime_tower && supports_wipe_tower_2);
+    toggle_line("single_extruder_multi_material_priming", !bSEMM && have_prime_tower && supports_wipe_tower_2 && !is_belt_printer);
 
     toggle_line("prime_volume",have_prime_tower && (!purge_in_primetower || !bSEMM));
 

src/slic3r/GUI/GLCanvas3D.cpp

@@ -2866,7 +2866,13 @@ void GLCanvas3D::reload_scene(bool refresh_immediately, bool force_full_scene_re
             need_wipe_tower |= dynamic_cast<const ConfigOptionBool*>(dconfig.option("enable_wrapping_detection"))->value;
         }
 
-        if (wt && (need_wipe_tower || filaments_count > 1) && !wxGetApp().plater()->only_gcode_mode() && !wxGetApp().plater()->is_gcode_3mf()) {
+        // Belt printers replace the classic wipe tower with the auto-generated
+        // belt purge prism (a real model object), so never draw the tower widget.
+        bool is_belt_printer = false;
+        if (const auto *belt_opt = wxGetApp().preset_bundle->printers.get_edited_preset().config.option<ConfigOptionBool>("belt_printer"))
+            is_belt_printer = belt_opt->value;
+
+        if (wt && !is_belt_printer && (need_wipe_tower || filaments_count > 1) && !wxGetApp().plater()->only_gcode_mode() && !wxGetApp().plater()->is_gcode_3mf()) {
             for (int plate_id = 0; plate_id < n_plates; plate_id++) {
                 // If print ByObject and there is only one object in the plate, the wipe tower is allowed to be generated.
                 PartPlate* part_plate = ppl.get_plate(plate_id);

src/slic3r/GUI/Jobs/ArrangeJob.cpp

@@ -291,6 +291,12 @@ void ArrangeJob::prepare_wipe_tower()
     bool enable_prime_tower = op && op->getBool();
     if (!enable_prime_tower || params.is_seq_print) return;
 
+    // Belt printers have no classic wipe tower; purging goes into the belt
+    // purge prism, which is a real model object and arranges like any other.
+    if (const auto *belt_opt = wxGetApp().preset_bundle->printers.get_edited_preset().config.option<ConfigOptionBool>("belt_printer");
+        belt_opt && belt_opt->value)
+        return;
+
     bool smooth_timelapse = false;
     auto sop = current_config.option("timelapse_type");
     if (sop) { smooth_timelapse = sop->getInt() == TimelapseType::tlSmooth; }

src/slic3r/GUI/Plater.cpp

@@ -5475,6 +5475,10 @@ struct Plater::priv
     void exit_gizmo();
     void remove(size_t obj_idx);
     bool delete_object_from_model(size_t obj_idx, bool refresh_immediately = true); //BBS
+    // ORCA-Belt: keep the auto-generated belt purge prism in sync with the
+    // config and plate contents. Returns true when the model was mutated
+    // (caller should refresh the scene).
+    bool ensure_belt_purge_tower();
     void delete_all_objects_from_model();
     void reset(bool apply_presets_change = false);
     void center_selection();
@@ -8879,6 +8883,225 @@ void Plater::priv::process_validation_warnings(const std::vector<StringObjectExc
 }
 
 
+// ORCA-Belt: auto-managed purge prism for belt printers. The classic wipe
+// tower is disabled in belt mode (its G-code bypasses the belt transform), so
+// filament-change purging is routed into this prism via flush_into_objects
+// (see Print::_plan_belt_purge()). The prism is a real model object so it is
+// sliced through the normal pipeline and picks up the belt rotation.
+//
+// Width across the belt is user-set (belt_purge_tower_width); height is sized
+// so each tilted slicing plane's cross-section through the prism can absorb
+// the worst-case purge volume of one layer; length follows the printed
+// objects along the belt (plus tilt lead-in/lead-out). Runs on every
+// background-process update, so it must be idempotent: it only mutates the
+// model when the desired prism differs from the existing one beyond coarse
+// tolerances.
+bool Plater::priv::ensure_belt_purge_tower()
+{
+    auto is_prism = [](const ModelObject *mo) {
+        const ConfigOption *opt = mo->config.option("belt_purge_tower_object");
+        return opt != nullptr && opt->getBool();
+    };
+
+    std::vector<int> prism_idxs;
+    for (int i = 0; i < (int) model.objects.size(); ++i)
+        if (is_prism(model.objects[i]))
+            prism_idxs.push_back(i);
+
+    // Deletes prism objects, keeping the sidebar and part plates in sync
+    // (same primitives as Plater::priv::remove(), minus scene update — the
+    // caller refreshes the scene).
+    auto remove_prisms = [this](const std::vector<int> &idxs) {
+        for (auto it = idxs.rbegin(); it != idxs.rend(); ++it) {
+            model.delete_object(size_t(*it));
+            partplate_list.notify_instance_removed(*it, -1);
+            sidebar->obj_list()->delete_object_from_list(size_t(*it));
+        }
+    };
+
+    const auto &printer_config = wxGetApp().preset_bundle->printers.get_edited_preset().config;
+    const auto &print_config   = wxGetApp().preset_bundle->prints.get_edited_preset().config;
+    auto       &project_config = wxGetApp().preset_bundle->project_config;
+
+    const auto *belt_opt = printer_config.option<ConfigOptionBool>("belt_printer");
+    const bool  belt     = belt_opt != nullptr && belt_opt->value;
+    const bool  prime_tower_enabled = print_config.has("enable_prime_tower") && print_config.opt_bool("enable_prime_tower");
+    const auto *seq_opt   = print_config.option<ConfigOptionEnum<PrintSequence>>("print_sequence");
+    const bool  by_object = seq_opt != nullptr && seq_opt->value == PrintSequence::ByObject;
+
+    // Filaments used and bounding extent of the non-prism objects on the
+    // current plate (1-based filament ids; volume extruder 0 = object default).
+    PartPlate    *plate = partplate_list.get_curr_plate();
+    std::set<int> filaments;
+    double        y_min = std::numeric_limits<double>::max();
+    double        y_max = -std::numeric_limits<double>::max();
+    double        z_max = 0.;
+    bool          have_objects = false;
+    if (belt && plate != nullptr) {
+        for (int obj_idx = 0; obj_idx < (int) model.objects.size(); ++obj_idx) {
+            const ModelObject *mo = model.objects[obj_idx];
+            if (is_prism(mo))
+                continue;
+            int obj_extruder = 1;
+            if (const ConfigOption *opt = mo->config.option("extruder"); opt != nullptr && opt->getInt() > 0)
+                obj_extruder = opt->getInt();
+            bool any_instance_on_plate = false;
+            for (int inst_idx = 0; inst_idx < (int) mo->instances.size(); ++inst_idx) {
+                if (!plate->contain_instance_totally(obj_idx, inst_idx))
+                    continue;
+                any_instance_on_plate = true;
+                const BoundingBoxf3 bb = mo->instance_bounding_box(inst_idx);
+                y_min = std::min(y_min, bb.min.y());
+                y_max = std::max(y_max, bb.max.y());
+                z_max = std::max(z_max, bb.max.z());
+            }
+            if (!any_instance_on_plate)
+                continue;
+            have_objects = true;
+            for (const ModelVolume *mv : mo->volumes)
+                for (int e : mv->get_extruders())
+                    filaments.insert(e > 0 ? e : obj_extruder);
+        }
+    }
+
+    const bool wanted = belt && prime_tower_enabled && !by_object && have_objects && filaments.size() > 1;
+    if (!wanted) {
+        if (prism_idxs.empty())
+            return false;
+        remove_prisms(prism_idxs);
+        BOOST_LOG_TRIVIAL(info) << "[BELT-DEBUG] belt purge tower removed (conditions not met)";
+        return true;
+    }
+
+    // --- Sizing -----------------------------------------------------------
+    const double width   = print_config.has("belt_purge_tower_width") ? std::max(1., print_config.opt_float("belt_purge_tower_width")) : 35.;
+    const double layer_h = print_config.has("layer_height") ? print_config.opt_float("layer_height") : 0.2;
+
+    // Belt tilt: standard belt printers rotate about X. For other axes (or no
+    // rotation) fall back to vertical slicing geometry (theta = 90 deg); the
+    // backend leftover warning catches any resulting under-absorption.
+    double      theta    = M_PI / 2.;
+    const auto *axis_opt = printer_config.option<ConfigOptionEnum<BeltRotationAxis>>("belt_slice_rotation");
+    const auto *angle_opt = printer_config.option<ConfigOptionFloat>("belt_slice_rotation_angle");
+    if (axis_opt != nullptr && axis_opt->value == BeltRotationAxis::X && angle_opt != nullptr && std::abs(angle_opt->value) > EPSILON)
+        theta = std::clamp(Geometry::deg2rad(std::abs(angle_opt->value)), Geometry::deg2rad(5.), M_PI / 2.);
+    const double sin_t = std::sin(theta);
+    const double cot_t = std::cos(theta) / sin_t;
+
+    // Worst-case purge volume of one layer: up to (filament count - 1)
+    // toolchanges, each needing the worst flush matrix entry (mirrors the
+    // volume selection in Print::_plan_belt_purge()).
+    const bool use_matrix = (print_config.has("purge_in_prime_tower") && print_config.opt_bool("purge_in_prime_tower"))
+        && (printer_config.has("single_extruder_multi_material") && printer_config.opt_bool("single_extruder_multi_material"));
+    double max_flush = print_config.has("prime_volume") ? print_config.opt_float("prime_volume") : 45.;
+    if (use_matrix) {
+        const size_t extruder_nums = wxGetApp().preset_bundle->get_printer_extruder_count();
+        const std::vector<double> matrix = get_flush_volumes_matrix(
+            project_config.option<ConfigOptionFloats>("flush_volumes_matrix")->values, 0, extruder_nums);
+        const auto * multi_opt = project_config.option<ConfigOptionFloats>("flush_multiplier");
+        const double multiplier = multi_opt != nullptr && !multi_opt->values.empty() ? multi_opt->get_at(0) : 1.;
+        const int    n_total    = (int) (std::sqrt(double(matrix.size())) + 0.5);
+        double       m          = 0.;
+        for (int i : filaments)
+            for (int j : filaments)
+                if (i != j && i <= n_total && j <= n_total)
+                    m = std::max(m, matrix[size_t(i - 1) * n_total + size_t(j - 1)]);
+        if (m > 0.)
+            max_flush = m * multiplier;
+    }
+    const double v_layer = double(filaments.size() - 1) * max_flush;
+
+    // One tilted slicing plane cuts a width x (height/sin) rectangle out of
+    // the prism interior; one layer slab absorbs that area x layer height.
+    const double eta    = 0.85; // perimeters/infill packing safety factor
+    double       height = v_layer * sin_t / (width * layer_h * eta);
+    const double printable_height = printer_config.has("printable_height") ? printer_config.opt_float("printable_height") : 250.;
+    height = std::clamp(height, 2. * layer_h, std::max(2. * layer_h, printable_height));
+
+    // Length along the belt: cover the objects' Y extent; a slicing plane
+    // spans height*cot(theta) of belt travel, so pad both ends with the full
+    // lead-in (tilt sign is padded symmetrically) plus the objects' top
+    // overhang along the belt.
+    const double margin  = 10.;
+    const double lead    = height * cot_t;
+    double       y_start = y_min - lead - margin;
+    double       y_end   = y_max + (z_max + height) * cot_t + margin;
+
+    const Vec3d plate_origin = plate->get_origin();
+    const auto *bed_opt      = printer_config.option<ConfigOptionPoints>("printable_area");
+    const bool  infinite_y   = printer_config.has("belt_printer_infinite_y") && printer_config.opt_bool("belt_printer_infinite_y");
+    double      lane_x       = plate_origin.x() + 5.; // fallback left lane
+    if (bed_opt != nullptr && !bed_opt->values.empty()) {
+        const BoundingBoxf bed_ext = get_extents(bed_opt->values);
+        lane_x = plate_origin.x() + bed_ext.min.x() + 5.;
+        if (!infinite_y) {
+            y_start = std::max(y_start, plate_origin.y() + bed_ext.min.y() + 1.);
+            y_end   = std::min(y_end, plate_origin.y() + bed_ext.max.y() - 1.);
+        }
+    }
+    const double length = std::max(y_end - y_start, 10.);
+
+    const Vec3d desired_size(width, length, height);
+    const Vec3d desired_center(lane_x + 0.5 * width, y_start + 0.5 * length, 0.5 * height);
+
+    // --- Idempotence check -------------------------------------------------
+    // Coarse tolerances so object nudges and sizing jitter do not regenerate
+    // the prism on every background-process tick.
+    if (prism_idxs.size() == 1) {
+        const ModelObject  *prism = model.objects[prism_idxs.front()];
+        const BoundingBoxf3 bb    = prism->bounding_box_exact();
+        if ((bb.size() - desired_size).cwiseAbs().maxCoeff() < 5. && (bb.center() - desired_center).cwiseAbs().maxCoeff() < 5.)
+            return false;
+    }
+
+    // --- (Re)create ---------------------------------------------------------
+    if (!prism_idxs.empty())
+        remove_prisms(prism_idxs);
+
+    ModelObject *new_object = model.add_object();
+    new_object->name        = _u8L("Belt Purge Tower");
+    new_object->add_instance();
+    ModelVolume *new_volume = new_object->add_volume(make_cube(width, length, height));
+    new_volume->name        = new_object->name;
+
+    auto &cfg = new_object->config;
+    cfg.set_key_value("belt_purge_tower_object", new ConfigOptionBool(true));
+    cfg.set_key_value("flush_into_objects", new ConfigOptionBool(true));
+    cfg.set_key_value("extruder", new ConfigOptionInt(1));
+    // Sacrificial solid prism: one wall, no shells, dense rectilinear infill —
+    // every extrusion is overriddable, so the absorbed volume matches the
+    // cross-section x layer-height estimate used for the height above.
+    cfg.set_key_value("wall_loops", new ConfigOptionInt(1));
+    cfg.set_key_value("top_shell_layers", new ConfigOptionInt(0));
+    cfg.set_key_value("bottom_shell_layers", new ConfigOptionInt(0));
+    cfg.set_key_value("sparse_infill_density", new ConfigOptionPercent(100));
+    cfg.set_key_value("sparse_infill_pattern", new ConfigOptionEnum<InfillPattern>(ipRectilinear));
+    cfg.set_key_value("enable_support", new ConfigOptionBool(false));
+    cfg.set_key_value("brim_type", new ConfigOptionEnum<BrimType>(btNoBrim));
+    cfg.set_key_value("seam_slope_type", new ConfigOptionEnum<SeamScarfType>(SeamScarfType::None));
+    cfg.set_key_value("precise_z_height", new ConfigOptionBool(false));
+
+    new_object->invalidate_bounding_box();
+    const BoundingBoxf3 mesh_bb = new_volume->mesh().bounding_box();
+    new_object->translate(-mesh_bb.center());
+    new_object->instances.front()->set_offset(desired_center);
+    new_object->ensure_on_bed();
+    new_object->instances.front()->set_assemble_transformation(new_object->instances.front()->get_transformation());
+
+    const size_t obj_idx = model.objects.size() - 1;
+    // Registers the object in the sidebar and notifies the part plates;
+    // selection is left untouched (auto-managed object).
+    sidebar->obj_list()->add_object_to_list(obj_idx, /*call_selection_changed=*/false);
+
+    BOOST_LOG_TRIVIAL(info) << "[BELT-DEBUG] belt purge tower generated"
+        << " W=" << width << " L=" << length << " H=" << height
+        << " v_layer=" << v_layer << " max_flush=" << max_flush
+        << " filaments=" << filaments.size()
+        << " theta_deg=" << Geometry::rad2deg(theta)
+        << " center=(" << desired_center.x() << "," << desired_center.y() << ")";
+    return true;
+}
+
 // Update background processing thread from the current config and Model.
 // Returns a bitmask of UpdateBackgroundProcessReturnState.
 unsigned int Plater::priv::update_background_process(bool force_validation, bool postpone_error_messages, bool switch_print)
@@ -8889,6 +9112,10 @@ unsigned int Plater::priv::update_background_process(bool force_validation, bool
     // If the update_background_process() was not called by the timer, kill the timer,
     // so the update_restart_background_process() will not be called again in vain.
     background_process_timer.Stop();
+    // ORCA-Belt: sync the auto-managed belt purge prism before the model is
+    // applied to the Print below, so the prism change rides this same apply.
+    if (printer_technology == ptFFF && this->ensure_belt_purge_tower())
+        return_state |= UPDATE_BACKGROUND_PROCESS_REFRESH_SCENE;
     // Update the "out of print bed" state of ModelInstances.
     update_print_volume_state();
     // Apply new config to the possibly running background task.

src/slic3r/GUI/Tab.cpp

@@ -3009,6 +3009,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("enable_tower_interface_cooldown_during_tower", "multimaterial_settings_prime_tower");
         optgroup->append_single_option_line("prime_tower_enable_framework", "multimaterial_settings_prime_tower");
         optgroup->append_single_option_line("prime_tower_width", "multimaterial_settings_prime_tower#width");
+        optgroup->append_single_option_line("belt_purge_tower_width", "multimaterial_settings_prime_tower");
         optgroup->append_single_option_line("prime_volume", "multimaterial_settings_prime_tower");
         optgroup->append_single_option_line("prime_tower_brim_width", "multimaterial_settings_prime_tower#brim-width");
         optgroup->append_single_option_line("prime_tower_infill_gap", "multimaterial_settings_prime_tower");