sublayers and more

src/slic3r/GUI/GLCanvas3D.cpp

@@ -8911,7 +8911,10 @@ void GLCanvas3D::_render_imgui_select_plate_toolbar()
                     m_sel_plate_toolbar.m_items[i]->slice_state = IMToolbarItem::SliceState::SLICE_FAILED;
             }
             else {
-                if ((!is_empty && !can_slice) || (plate_list.get_plate(i)->has_printable_instances() && !plate_list.get_plate(i)->can_slice()))
+                // A plate using a mixed filament whose components are broken cannot be sliced,
+                // so surface that on the plate toolbar the same way an unsliceable plate is.
+                if ((!is_empty && !can_slice) || (plate_list.get_plate(i)->has_printable_instances() && !plate_list.get_plate(i)->can_slice())
+                    || wxGetApp().plater()->sidebar().has_broken_mixed_filament(plate_list.get_plate(i)))
                     m_sel_plate_toolbar.m_items[i]->slice_state = IMToolbarItem::SliceState::SLICE_FAILED;
                 else {
                     if (plate_list.get_plate(i)->get_slicing_percent() < 0.0f)
@@ -9707,6 +9710,10 @@ void GLCanvas3D::_render_paint_toolbar() const
     bool disabled = !wxGetApp().plater()->can_fillcolor();
     ColorRGBA rgba;
 
+    // Gradient mixed filaments fade between two colours over Z, so their swatch is drawn as a
+    // two-tone fade rather than the single blended colour in `colors`.
+    auto gradient_info = wxGetApp().plater()->get_filament_gradient_info();
+
     for (int i = 0; i < extruder_num; i++) {
         if (i > 0)
             ImGui::SameLine();
@@ -9720,6 +9727,16 @@ void GLCanvas3D::_render_paint_toolbar() const
             if (!ImGui::IsMouseHoveringRect(left_arrow_button.Min, left_arrow_button.Max) && !ImGui::IsMouseHoveringRect(right_arrow_button.Min, right_arrow_button.Max))
                 wxPostEvent(m_canvas, IntEvent(EVT_GLTOOLBAR_FILLCOLOR, i + 1));
         }
+        if (i < (int) gradient_info.size() && gradient_info[i].is_gradient) {
+            auto to_imu32 = [](const std::array<float, 4> &c) -> ImU32 {
+                return IM_COL32(uint8_t(c[0]*255.f), uint8_t(c[1]*255.f), uint8_t(c[2]*255.f), uint8_t(c[3]*255.f));
+            };
+            ImVec2 r_min = ImGui::GetItemRectMin();
+            ImVec2 r_max = ImGui::GetItemRectMax();
+            ImU32 col_from = to_imu32(gradient_info[i].color_from);
+            ImU32 col_to   = to_imu32(gradient_info[i].color_to);
+            ImGui::GetWindowDrawList()->AddRectFilledMultiColor(r_min, r_max, col_from, col_to, col_to, col_from);
+        }
         if (ImGui::IsItemHovered() && i < 9) {
             if (!ImGui::IsMouseHoveringRect(left_arrow_button.Min, left_arrow_button.Max) && !ImGui::IsMouseHoveringRect(right_arrow_button.Min, right_arrow_button.Max)) {
                 ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, { 20.0f * f_scale, 10.0f * f_scale });

src/slic3r/GUI/GUI_Factories.cpp

@@ -1684,11 +1684,18 @@ void MenuFactory::create_filament_action_menu(bool init, int active_filament_men
     append_submenu(menu, sub_menu, wxID_ANY, _L("Merge with"), "", "",
         [filaments_cnt]() { return filaments_cnt > 1; }, m_parent);
 
+    // Decompose a target colour into a printable mix of the loaded filaments. Placed before the
+    // Delete entry below so Orca's "delete last" ordering is preserved (BBS appends it after).
+    append_menu_item(
+        menu, wxID_ANY, _L("Decompose Color"), "", [](wxCommandEvent&) {
+            plater()->sidebar().decompose_filament_color(kSidebarContextMenuFilamentId); }, "", nullptr,
+        []() { return plater()->sidebar().combos_filament().size() >= 2; }, m_parent);
+
     // ORCA use delete item on end of menu to prevent accidental clicks. clicking to submenus(merge) already not allowed by OS
     const int delete_id = menu->FindItem(_L("Delete"));
     if (delete_id != wxNOT_FOUND)
         menu->Destroy(delete_id);
-    
+
     append_menu_item(
         menu, wxID_ANY, _L("Delete"), _L("Delete this filament"), [](wxCommandEvent&) {
             plater()->sidebar().delete_filament(-2); }, "", nullptr,

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.cpp

@@ -78,6 +78,14 @@ void GLGizmoMmuSegmentation::init_extruders_data()
     m_extruders_colors      = wxGetApp().plater()->get_extruders_colors();
     m_selected_extruder_idx = 0;
 
+    auto plater_grad = wxGetApp().plater()->get_filament_gradient_info();
+    m_gradient_info.resize(m_extruders_colors.size());
+    for (size_t i = 0; i < m_gradient_info.size() && i < plater_grad.size(); ++i) {
+        m_gradient_info[i].is_gradient = plater_grad[i].is_gradient;
+        m_gradient_info[i].color_from  = plater_grad[i].color_from;
+        m_gradient_info[i].color_to    = plater_grad[i].color_to;
+    }
+
     // keep remap table consistent with current extruder count
     m_extruder_remap.resize(m_extruders_colors.size());
     for (size_t i = 0; i < m_extruder_remap.size(); ++i)
@@ -433,6 +441,19 @@ void GLGizmoMmuSegmentation::on_render_input_window(float x, float y, float bott
             m_selected_extruder_idx = extruder_idx;
         }
 
+        // Overlay a two-tone fade for gradient mixed filaments; a single flat colour would
+        // misrepresent a slot that fades between two filaments over Z.
+        if (extruder_idx < (int) m_gradient_info.size() && m_gradient_info[extruder_idx].is_gradient) {
+            auto to_imu32 = [](const std::array<float, 4> &c) -> ImU32 {
+                return IM_COL32(uint8_t(c[0]*255.f), uint8_t(c[1]*255.f), uint8_t(c[2]*255.f), uint8_t(c[3]*255.f));
+            };
+            ImVec2 r_min = ImGui::GetItemRectMin();
+            ImVec2 r_max = ImGui::GetItemRectMax();
+            ImU32 col_from = to_imu32(m_gradient_info[extruder_idx].color_from);
+            ImU32 col_to   = to_imu32(m_gradient_info[extruder_idx].color_to);
+            ImGui::GetWindowDrawList()->AddRectFilledMultiColor(r_min, r_max, col_from, col_to, col_to, col_from);
+        }
+
         if (extruder_idx < 16 && 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). 

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.hpp

@@ -79,6 +79,14 @@ public:
     // 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;
 
+    // Endpoint colours for gradient mixed filaments, mirrored from Plater so the extruder
+    // swatches below can be drawn as a two-tone fade instead of a single blended colour.
+    struct GradientInfo {
+        bool is_gradient = false;
+        std::array<float, 4> color_from = {0.5f, 0.5f, 0.5f, 1.0f};
+        std::array<float, 4> color_to   = {0.5f, 0.5f, 0.5f, 1.0f};
+    };
+
     const float get_cursor_radius_min() const override { return CursorRadiusMin; }
 
     // BBS
@@ -116,6 +124,7 @@ protected:
     
     // Filament remap feature
     std::vector<size_t>               m_extruder_remap;      // index → target extruder index
+    std::vector<GradientInfo>         m_gradient_info;       // per-slot gradient endpoints, empty entries for plain filaments
     // ORCA: Cache used filaments to filter UI
     std::set<size_t>                  m_used_filaments;      // Set of used filament indices (cached)
 

src/slic3r/GUI/PlateSettingsDialog.cpp

@@ -472,6 +472,32 @@ PlateSettingsDialog::PlateSettingsDialog(wxWindow* parent, const wxString& title
     m_sizer_main->AddSpacer(FromDIP(5));
     m_sizer_main->Add(m_other_layers_seq_panel, 0, wxEXPAND | wxLEFT | wxRIGHT, FromDIP(30));
 
+    // A mixed-color slot resolves to a different physical filament per layer, so a user-defined
+    // filament order cannot be honoured. Disable the choice and say why. BBS puts this warning
+    // inside its button sizer; Orca builds the buttons with DialogButtons, so it gets its own row.
+    {
+        auto &proj_cfg     = wxGetApp().preset_bundle->project_config;
+        auto *is_mixed_opt = proj_cfg.option<ConfigOptionBools>("filament_is_mixed");
+        if (is_mixed_opt && Slic3r::has_any_mixed_filament(is_mixed_opt->values)) {
+            m_first_layer_print_seq_choice->Enable(false);
+            m_other_layers_seq_panel->enable_seq_choice(false);
+
+            auto *warn_sizer = new wxBoxSizer(wxHORIZONTAL);
+            auto *warn_icon  = new wxStaticBitmap(this, wxID_ANY, create_scaled_bitmap("warning", this, 16),
+                                                  wxDefaultPosition, wxSize(FromDIP(16), FromDIP(16)));
+            auto *warn_text  = new wxStaticText(this, wxID_ANY,
+                _L("The filament list contains mixed filaments. Custom filament sequence will not take effect."));
+            warn_text->SetForegroundColour(wxColour(255, 111, 0));
+            warn_text->SetFont(Label::Body_12);
+            warn_text->Wrap(FromDIP(300));
+
+            warn_sizer->Add(warn_icon, 0, wxALIGN_CENTER_VERTICAL | wxRIGHT, FromDIP(5));
+            warn_sizer->Add(warn_text, 1, wxALIGN_CENTER_VERTICAL, 0);
+            m_sizer_main->AddSpacer(FromDIP(5));
+            m_sizer_main->Add(warn_sizer, 0, wxEXPAND | wxLEFT | wxRIGHT, FromDIP(30));
+        }
+    }
+
     auto dlg_btns = new DialogButtons(this, {"OK", "Cancel"});
 
     dlg_btns->GetOK()->Bind(wxEVT_BUTTON, [this](auto& e) {

src/slic3r/GUI/PlateSettingsDialog.hpp

@@ -62,6 +62,9 @@ public:
     int get_layers_print_seq_choice() { return m_other_layer_print_seq_choice->GetSelection(); };
 
     std::vector<LayerSeqInfo> get_layers_print_seq_infos() { return m_layer_seq_infos; }
+    // Lets callers grey out the sequence choice (e.g. when a mixed filament makes a
+    // user-defined filament order impossible).
+    void enable_seq_choice(bool enable) { m_other_layer_print_seq_choice->Enable(enable); }
 
 protected:
     void append_layer(const LayerSeqInfo* layer_info = nullptr);

src/slic3r/GUI/Plater.cpp

@@ -5355,9 +5355,16 @@ void Sidebar::delete_filament(size_t filament_id, int replace_filament_id) {
         p->editing_filament = -1;
     }
 
+    // update_num_filaments() shrinks filament_is_mixed along with the other per-filament arrays,
+    // so snapshot it first — the paint cleanup below needs to know which slots were mixed
+    // *before* the delete to avoid discarding assignments to still-valid mixed slots.
+    std::vector<unsigned char> is_mixed_snapshot;
+    if (auto* opt = wxGetApp().preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed"))
+        is_mixed_snapshot = opt->values;
+
     wxGetApp().preset_bundle->update_num_filaments(filament_id);
     wxGetApp().plater()->get_partplate_list().on_filament_deleted(filament_count, filament_id);
-    wxGetApp().plater()->on_filaments_delete(filament_count, filament_id, replace_filament_id > (int)filament_id ? (replace_filament_id - 1) : replace_filament_id);
+    wxGetApp().plater()->on_filaments_delete(filament_count, filament_id, replace_filament_id > (int)filament_id ? (replace_filament_id - 1) : replace_filament_id, is_mixed_snapshot);
     wxGetApp().get_tab(Preset::TYPE_PRINT)->update();
     wxGetApp().preset_bundle->export_selections(*wxGetApp().app_config);
 
@@ -5374,6 +5381,36 @@ void Sidebar::delete_filament(size_t filament_id, int replace_filament_id) {
 
 void Sidebar::change_filament(size_t from_id, size_t to_id)
 {
+    // Merging a physical filament into a mixed one that lists it as a component would delete
+    // the very filament the mix depends on, leaving it broken. Warn before doing so.
+    auto& pb = *wxGetApp().preset_bundle;
+    bool from_is_physical = !pb.is_mixed_filament(from_id);
+    bool to_is_mixed = pb.is_mixed_filament(to_id);
+
+    if (from_is_physical && to_is_mixed) {
+        auto* comp_opt = pb.project_config.option<ConfigOptionStrings>("filament_mixed_components");
+        if (comp_opt && to_id < comp_opt->values.size()) {
+            auto comps = Slic3r::parse_mixed_components(comp_opt->values[to_id]);
+            unsigned int from_1based = (unsigned int)from_id + 1;
+            bool target_uses_source = false;
+            for (unsigned int c : comps) {
+                if (c == from_1based) {
+                    target_uses_source = true;
+                    break;
+                }
+            }
+            if (target_uses_source) {
+                int ret = wxMessageBox(
+                    _L("The target mixed filament uses this physical filament as a component. "
+                       "Merging will remove this physical filament and may invalidate the mixed filament. Continue?"),
+                    _L("Warning"),
+                    wxOK | wxCANCEL | wxICON_WARNING);
+                if (ret != wxOK)
+                    return;
+            }
+        }
+    }
+
     delete_filament(from_id, int(to_id));
 }
 
@@ -9744,7 +9781,11 @@ void Plater::priv::object_list_changed()
 
     // BBS
     //sidebar->enable_buttons(!model.objects.empty() && !export_in_progress && model_fits && part_plate->has_printable_instances());
-    bool can_slice = !model.objects.empty() && !export_in_progress && model_fits && part_plate->has_printable_instances();
+    // A mixed filament with deleted or type-mismatched components cannot be resolved at slicing
+    // time, so block the slice buttons the same way MainFrame::get_enable_slice_status() does.
+    bool mixed_broken = sidebar->has_broken_mixed_filament();
+    bool can_slice = !model.objects.empty() && !export_in_progress && model_fits && part_plate->has_printable_instances()
+                     && !mixed_broken;
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": can_slice %1%, model_fits= %2%, export_in_progress %3%, has_printable_instances %4% ")%can_slice %model_fits %export_in_progress %part_plate->has_printable_instances();
     main_frame->update_slice_print_status(MainFrame::eEventObjectUpdate, can_slice);
 
@@ -13963,6 +14004,25 @@ bool Plater::priv::can_layers_editing() const
 
 void Plater::priv::on_action_layersediting(SimpleEvent&)
 {
+    // Sub-layer splitting divides each layer by the mix ratio, so an adaptive layer profile makes
+    // those sub-layer heights vary and degrades the blend. ConfigManipulation warns when the
+    // option is switched on with a variable profile already present; this is the other direction,
+    // warning when variable layer editing is switched on while the option is active. Both honour
+    // the same do-not-show-again flag.
+    if (!view3D->is_layers_editing_enabled()) {
+        const auto& print_config = wxGetApp().preset_bundle->prints.get_edited_preset().config;
+        if (print_config.opt_bool("enable_mixed_color_sublayer")) {
+            if (wxGetApp().app_config->get("no_warn_mixed_sublayer_variable_layer") != "1") {
+                MessageDialog dlg(q,
+                    _L("Using variable layer height together with mixed color sublayer may result in poor color mixing quality."),
+                    _L("Warning"), wxICON_WARNING | wxOK);
+                dlg.show_dsa_button();
+                dlg.ShowModal();
+                if (dlg.get_checkbox_state())
+                    wxGetApp().app_config->set("no_warn_mixed_sublayer_variable_layer", "1");
+            }
+        }
+    }
     view3D->enable_layers_editing(!view3D->is_layers_editing_enabled());
     notification_manager->set_move_from_overlay(view3D->is_layers_editing_enabled());
 }
@@ -19385,7 +19445,7 @@ void Plater::on_filament_count_change(size_t num_filaments)
     }
 }
 
-void Plater::on_filaments_delete(size_t num_filaments, size_t filament_id, int replace_filament_id)
+void Plater::on_filaments_delete(size_t num_filaments, size_t filament_id, int replace_filament_id, const std::vector<unsigned char>& is_mixed_before_delete)
 {
     // only update elements in plater
     update_filament_colors_in_full_config();
@@ -19399,9 +19459,15 @@ void Plater::on_filaments_delete(size_t num_filaments, size_t filament_id, int r
     }*/
 
     // update mmu info
+    // A volume assigned to a mixed slot legitimately sits past the physical filament count, so
+    // the paint cleanup must know which slots were mixed. Callers that already shrank the arrays
+    // pass the pre-delete flags; otherwise read the current ones.
+    const auto &is_mixed = is_mixed_before_delete.empty()
+        ? wxGetApp().preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed")->values
+        : is_mixed_before_delete;
     for (ModelObject *mo : wxGetApp().model().objects) {
         for (ModelVolume *mv : mo->volumes) {
-            mv->update_extruder_count_when_delete_filament(num_filaments, filament_id + 1, replace_filament_id + 1);  // this function is 1 base
+            mv->update_extruder_count_when_delete_filament(num_filaments, filament_id + 1, replace_filament_id + 1, is_mixed);  // this function is 1 base
         }
     }
 
@@ -19740,6 +19806,63 @@ std::vector<std::string> Plater::get_extruder_colors_from_plater_config(const GC
     }
 }
 
+namespace {
+
+// A gradient mixed filament fades between its two components over Z, so the UI shows it as a
+// two-tone swatch rather than one blended colour. Resolve each slot to its from/to endpoint
+// colours; non-gradient slots are left untouched.
+struct MixedGradientSlot {
+    bool        is_gradient = false;
+    std::string color_from;
+    std::string color_to;
+};
+
+std::vector<MixedGradientSlot> parse_mixed_gradient_slots(const Slic3r::DynamicPrintConfig& config, size_t slot_count)
+{
+    std::vector<MixedGradientSlot> result(slot_count);
+    const auto* is_mixed   = config.option<ConfigOptionBools>("filament_is_mixed");
+    const auto* mixed_grad = config.option<ConfigOptionBools>("filament_mixed_gradient");
+    const auto* mixed_comp = config.option<ConfigOptionStrings>("filament_mixed_components");
+    const auto* grad_range = config.option<ConfigOptionStrings>("filament_mixed_gradient_range");
+    const auto* fil_colour = config.option<ConfigOptionStrings>("filament_colour");
+    if (!is_mixed || !mixed_grad || !mixed_comp || !fil_colour) return result;
+
+    for (size_t i = 0; i < slot_count && i < is_mixed->values.size(); ++i) {
+        if (!is_mixed->values[i]) continue;
+        if (i >= mixed_grad->values.size() || !mixed_grad->values[i]) continue;
+        if (i >= mixed_comp->values.size()) continue;
+
+        std::vector<unsigned int> comp_ids;
+        std::istringstream iss(mixed_comp->values[i]);
+        std::string tok;
+        while (std::getline(iss, tok, ',')) {
+            unsigned int v = 0;
+            if (std::sscanf(tok.c_str(), "%u", &v) == 1)
+                comp_ids.push_back(v);
+        }
+        if (comp_ids.size() != 2) continue;
+
+        int direction = 0;
+        if (grad_range && i < grad_range->values.size()) {
+            CNumericLocalesSetter c_locale_setter;
+            float v0 = 0, v1 = 0;
+            if (std::sscanf(grad_range->values[i].c_str(), "%f,%f", &v0, &v1) == 2)
+                direction = (v0 > v1) ? 0 : 1;
+        }
+
+        unsigned int from_id = (direction == 0) ? comp_ids[0] : comp_ids[1];
+        unsigned int to_id   = (direction == 0) ? comp_ids[1] : comp_ids[0];
+        result[i].is_gradient = true;
+        result[i].color_from = (from_id >= 1 && from_id <= fil_colour->values.size())
+            ? fil_colour->values[from_id - 1] : "#D9D9D9";
+        result[i].color_to = (to_id >= 1 && to_id <= fil_colour->values.size())
+            ? fil_colour->values[to_id - 1] : "#D9D9D9";
+    }
+    return result;
+}
+
+} // anonymous namespace
+
 std::vector<std::string> Plater::get_filament_colors_render_info() const
 {
     const Slic3r::DynamicPrintConfig* config = &wxGetApp().preset_bundle->project_config;
@@ -19747,6 +19870,13 @@ std::vector<std::string> Plater::get_filament_colors_render_info() const
     if (!config->has("filament_multi_colour")) return color_packs;
 
     color_packs = (config->option<ConfigOptionStrings>("filament_multi_colour"))->values;
+
+    auto slots = parse_mixed_gradient_slots(*config, color_packs.size());
+    for (size_t i = 0; i < color_packs.size(); ++i) {
+        if (slots[i].is_gradient)
+            color_packs[i] = slots[i].color_from + " " + slots[i].color_to;
+    }
+
     return color_packs;
 }
 
@@ -19757,9 +19887,37 @@ std::vector<std::string> Plater::get_filament_color_render_type() const
     if (!config->has("filament_colour_type")) return ctype;
 
     ctype = (config->option<ConfigOptionStrings>("filament_colour_type"))->values;
+
+    auto slots = parse_mixed_gradient_slots(*config, ctype.size());
+    while (ctype.size() < slots.size()) ctype.push_back("1");
+    for (size_t i = 0; i < ctype.size() && i < slots.size(); ++i) {
+        if (slots[i].is_gradient)
+            ctype[i] = "0";
+    }
+
     return ctype;
 }
 
+std::vector<Plater::FilamentGradientInfo> Plater::get_filament_gradient_info() const
+{
+    const Slic3r::DynamicPrintConfig* config = &wxGetApp().preset_bundle->project_config;
+    size_t n = get_extruder_colors_from_plater_config().size();
+    std::vector<FilamentGradientInfo> info(n);
+
+    auto slots = parse_mixed_gradient_slots(*config, n);
+    unsigned char rgba[4] = {};
+    for (size_t i = 0; i < n; ++i) {
+        if (!slots[i].is_gradient) continue;
+        info[i].is_gradient = true;
+        Slic3r::GUI::BitmapCache::parse_color4(slots[i].color_from, rgba);
+        info[i].color_from = {rgba[0] / 255.f, rgba[1] / 255.f, rgba[2] / 255.f, rgba[3] / 255.f};
+        Slic3r::GUI::BitmapCache::parse_color4(slots[i].color_to, rgba);
+        info[i].color_to = {rgba[0] / 255.f, rgba[1] / 255.f, rgba[2] / 255.f, rgba[3] / 255.f};
+    }
+
+    return info;
+}
+
 /* Get vector of colors used for rendering of a Preview scene in "Color print" mode
  * It consists of extruder colors and colors, saved in model.custom_gcode_per_print_z
  */

src/slic3r/GUI/Plater.hpp

@@ -591,7 +591,7 @@ 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 = {});
     std::vector<Slic3r::ColorRGBA> get_extruders_colors();
     // BBS
     void on_bed_type_change(BedType bed_type);
@@ -606,6 +606,15 @@ public:
     std::vector<std::string> get_extruder_colors_from_plater_config(const GCodeProcessorResult* const result = nullptr) const;
     std::vector<std::string> get_filament_colors_render_info() const;
     std::vector<std::string> get_filament_color_render_type() const;
+
+    // Endpoint colours for gradient mixed filaments, so the 3D scene and the paint gizmo can
+    // draw a two-tone swatch. is_gradient is false for every ordinary filament slot.
+    struct FilamentGradientInfo {
+        bool is_gradient = false;
+        std::array<float, 4> color_from = {0.5f, 0.5f, 0.5f, 1.0f};
+        std::array<float, 4> color_to   = {0.5f, 0.5f, 0.5f, 1.0f};
+    };
+    std::vector<FilamentGradientInfo> get_filament_gradient_info() const;
     std::vector<std::string> get_colors_for_color_print(const GCodeProcessorResult* const result = nullptr) const;
 
     void set_global_filament_map_mode(FilamentMapMode mode);

src/slic3r/GUI/SyncAmsInfoDialog.cpp

@@ -2575,6 +2575,10 @@ void SyncAmsInfoDialog::reset_and_sync_ams_list()
     m_materialList.clear();
     m_filaments.clear();
 
+    // Mixed-color slots are virtual: they never occupy a tray, so they must not appear as
+    // AMS sync targets. Look the flags up once and skip those slots in the loop below.
+    auto* is_mixed_opt = preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed");
+
     bool use_double_extruder = get_is_double_extruder();
     if (use_double_extruder) {
         const auto &project_config = preset_bundle->project_config;
@@ -2592,6 +2596,8 @@ void SyncAmsInfoDialog::reset_and_sync_ams_list()
         auto colour_rgb = wxColour((int) rgb[0], (int) rgb[1], (int) rgb[2], (int) rgb[3]);
         if (extruder >= materials.size() || extruder < 0 || extruder >= display_materials.size())
             continue;
+        if (is_mixed_opt && extruder < (int) is_mixed_opt->values.size() && is_mixed_opt->values[extruder])
+            continue;
 
         if (contronal_index % SYNC_FLEX_GRID_COL == 0) {
             wxBoxSizer *ams_tip_sizer = new wxBoxSizer(wxVERTICAL);
@@ -2793,6 +2799,10 @@ void SyncAmsInfoDialog::generate_override_fix_ams_list()
     m_fix_materialList.clear();
     m_fix_filaments.clear();
 
+    // Mixed-color slots are virtual: they never occupy a tray, so they must not appear as
+    // AMS sync targets. Look the flags up once and skip those slots in the loop below.
+    auto* is_mixed_opt = preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed");
+
     bool use_double_extruder = get_is_double_extruder();
     if (use_double_extruder) {
         const auto &project_config = preset_bundle->project_config;
@@ -2810,6 +2820,8 @@ void SyncAmsInfoDialog::generate_override_fix_ams_list()
         auto colour_rgb = wxColour((int) rgb[0], (int) rgb[1], (int) rgb[2], (int) rgb[3]);
         if (extruder >= extruders.size() || extruder < 0 || extruder >= m_ams_combo_info.ams_filament_colors.size())
             continue;
+        if (is_mixed_opt && extruder < (int) is_mixed_opt->values.size() && is_mixed_opt->values[extruder])
+            continue;
 
         if (contronal_index % SYNC_FLEX_GRID_COL == 0) {
             wxBoxSizer *ams_tip_sizer = new wxBoxSizer(wxVERTICAL);

src/slic3r/GUI/Tab.cpp

@@ -2630,6 +2630,7 @@ 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("enable_mixed_color_sublayer");
 
         optgroup = page->new_optgroup(L("Line width"), L"param_line_width");
         optgroup->append_single_option_line("line_width","quality_settings_line_width");