init work to integrate OrcaSlicer-FullSpectrum fork Integrations up to commit b3c41fda41.

- libslic3r: vendor FilamentMixer; MixedFilamentManager (auto-gen, resolve,
    serialize; manual-pattern / gradient / pointillism); 19 new PrintConfig
    keys; PresetBundle owns the canonical manager with 3MF + AppConfig
    roundtrip and AMS-safe strip+restore; Print owns the slicing-time copy
    with PrintApply auto-regen on color change; TriangleSelector::
    shift_states_above + filament-id remap; inset_idx propagation through
    ExtrusionPath/Loop/MultiPath copy/assign.
  - Slicing: virtual filament IDs in painted regions (same-physical channels
    collapse when mixed_filament_region_collapse is on); ByObject
    collect_filament_data expands mixed slots; pair-cadence + whole-object +
    3+component Local-Z plan generators; LocalZOrderOptimizer utility.
  - GCode + ToolOrdering: LayerTools resolves virtual IDs through wall /
    infill / sparse / solid queries; SameLayerPointillisme in process_layer
    (uniform-segment + grouped per-perimeter-index splitters); WipeTower2
    Local-Z reservation + sub-layer G-code emission; per-layer infill
    filament override.
  - PartPlate: get_extruders* expand virtual slots into physical components;
    CLI path rebuilds a local manager from full_config.
  - GUI: five widget files extracted from FS Plater.cpp (~5000 LOC) —
    MixedMixPreview, MixedGradientSelector + WeightsDialog,
    MixedFilamentColorMapPanel, MixedFilamentColorMatchDialog (ΔE₀₀ recipe
    search), MixedFilamentConfigPanel; Sidebar Mixed Filaments panel
    (drag-reorder, enable/delete, Add Gradient/Pattern/Color); Tab exposure
    of mixed-filament / dithering / per-layer infill-override settings +
    ConfigManipulation visibility and slot-validation rules;
    BBLMixedFilamentBroken / BBLSingleExtruderMixedFilamentRisk
    notifications + slice gate; WipeTowerDialog edits physical P×P
    sub-matrix; bounds-safe extruder_id guards in 3DScene / GLCanvas3D /
    GLGizmoMmuSegmentation; change_filament merge guard and
    on_filaments_delete is_mixed_before_delete propagation.
  - Tests: 4 Catch2 tests for 3MF roundtrip (auto/custom persistence,
    PresetBundle string path, total_filaments stability); full-pipeline
    slice E2E deferred — TODO in file.

Co-authored-by: Rad <radugheorghiu96@gmail.com>
Co-authored-by: Justin Hayes <justinh@rahb.ca>
Co-authored-by: Calogero Guagenti <calogeroguagenti@gmail.com>
Co-authored-by: xSil3nt <ahmedshazin21@gmail.com>
Co-authored-by: ratdoux <62392831+ratdoux@users.noreply.github.com>

Update TriangleSelector.cpp

Co-Authored-By: Rad <radugheorghiu96@gmail.com>
Co-Authored-By: Justin Hayes <justinh@rahb.ca>
Co-Authored-By: Calogero Guagenti <calogeroguagenti@gmail.com>
Co-Authored-By: xSil3nt <ahmedshazin21@gmail.com>
Co-Authored-By: ratdoux <62392831+ratdoux@users.noreply.github.com>

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]);
     }