clean up comments

src/libslic3r/Format/OBJ.hpp

@@ -38,8 +38,8 @@ extern bool load_obj(const char *path, TriangleMesh *mesh, ObjInfo &vertex_color
 extern bool load_obj(const char *path, Model *model, ObjInfo &vertex_colors, std::string &message, const char *object_name = nullptr, ObjParser::MtlData *out_mtl = nullptr);
 
 struct TexturedMesh;
-// Build a TexturedMesh (vertices + per-face UVs + decoded texture images) from a parsed OBJ
-// plus its material table, so the texture-to-color importer can sample face colours.
+// Build a TexturedMesh (vertices + per-face UVs + the texture files named by map_Kd) from a
+// parsed OBJ plus its material table, so the texture-to-color importer can sample face colours.
 extern bool obj_to_textured_mesh(
     const ObjInfo& obj_info,
     const indexed_triangle_set& its,

src/libslic3r/GCode.cpp

@@ -6106,8 +6106,7 @@ LayerResult GCode::process_layer(
         // A mixed-color slot is absent from layer_tools.extruders by design: resolve_mixed_filaments()
         // replaced it with its physical components. Its geometry is still keyed under the slot in
         // by_extruder though, and the sublayer emitter looks the plan up by slot id, so append the
-        // slots here. Appended (not merged) so the existing order is untouched, and empty for every
-        // configuration without sublayer splitting.
+        // slots here. Appending rather than merging leaves the flush-optimized order untouched.
         std::vector<unsigned int> plan_filaments = layer_tools.extruders;
         for (const auto &grp : layer_tools.mixed_sub_layer_groups)
             if (std::find(plan_filaments.begin(), plan_filaments.end(), grp.mixed_slot_0based) == plan_filaments.end())
@@ -6593,8 +6592,8 @@ LayerResult GCode::process_layer(
 
         // Mixed-color sublayer extrusion: if this extruder is a component of a mixed sublayer
         // group, extrude the mixed slot's geometry at the appropriate sub-Z with scaled flow.
-        // Ported from BambuStudio's 混色耗材 feature; adapted to Orca's InstanceVisit-based
-        // instance loop and its finer-grained per-role region filament options.
+        // Ported from BambuStudio and adapted to Orca's instance loop and its finer-grained
+        // per-role region filament options.
         for (const auto &grp : layer_tools.mixed_sub_layer_groups) {
             int sub_idx = -1;
             for (size_t k = 0; k < grp.components_0based.size(); ++k) {

src/libslic3r/GCode/ToolOrdering.cpp

@@ -91,11 +91,9 @@ bool check_filament_printable_after_group(const std::vector<unsigned int> &used_
 }
 
 // Return a zero based extruder from the region, or extruder_override if overriden.
-// The region accessors below resolve mixed-color slots to the physical filament chosen for
-// this layer. Without sub-layer splitting a mixed slot is realized by alternating whole layers
-// (deficit round-robin, see resolve_mixed_filaments), so a region asking "which filament?" must
-// get the resolved physical one, not the virtual slot id. resolve_mixed() is identity when the
-// slot is not mixed, so this is a no-op for every non-mixed setup.
+// The region accessors below resolve mixed-color slots to the physical filament chosen for this
+// layer by resolve_mixed_filaments(), because a virtual slot id is never a real tool. resolve_mixed()
+// returns its argument unchanged for every filament that is not a mixed slot.
 unsigned int LayerTools::wall_extruder_id(const PrintRegion &region) const
 {
 	assert(region.config().outer_wall_filament_id.value > 0);
@@ -2522,8 +2520,7 @@ void ToolOrdering::resolve_mixed_filaments(const PrintConfig &config)
                 //  - untagged region (modifier / painted / etc.) -> per_object_gradient[obj]
                 // Populating both keeps the per-object run state correct even when per-volume
                 // takes over for the same (slot, obj), and lets untagged geometry (which is
-                // explicitly NOT split per-volume in v1 per the design doc) keep its legacy
-                // per-object gradient ratios.
+                // never split per-volume) keep its per-object gradient ratios.
                 if (grp.is_gradient) {
                     auto vol_runs_slot_it = per_vol_runs.find(ext);
                     if (vol_runs_slot_it != per_vol_runs.end()) {

src/libslic3r/Model.cpp

@@ -309,9 +309,8 @@ Model Model::read_from_file(const std::string&
         ObjParser::MtlData      mtl_data;
         result = load_obj(input_file.c_str(), &model, obj_info, message, nullptr, &mtl_data);
         if (result && obj_info.has_uv_png && !obj_info.uvs.empty() && !model.objects.empty()) {
-            // Textured OBJ: hand the mesh + materials to the texture-to-color importer instead
-            // of the flat per-face colour dialog. Replaces Orca's previous "not implemented"
-            // placeholder for this branch.
+            // Textured OBJ: hand the mesh + materials to the texture-to-color importer
+            // instead of the flat per-face colour dialog.
             auto tex_mesh = std::make_shared<TexturedMesh>();
             std::string obj_dir = boost::filesystem::path(input_file).parent_path().string();
             if (obj_to_textured_mesh(obj_info,
@@ -322,7 +321,7 @@ Model Model::read_from_file(const std::string&
         }
         else if (result && !model.objects.empty() && !model.objects.back()->volumes.empty()) {
             // Vertex-colour and MTL face-colour OBJs also go through the texture-to-color
-            // importer (as precomputed per-face colors) instead of the legacy flat
+            // importer (as precomputed per-face colors) instead of the flat
             // per-face colour dialog, matching the uv_png branch above.
             auto build_tex_mesh_geometry = [&]() {
                 auto tex_mesh = std::make_shared<TexturedMesh>();
@@ -374,7 +373,7 @@ Model Model::read_from_file(const std::string&
     else if (boost::algorithm::iends_with(input_file, ".glb") ||
              boost::algorithm::iends_with(input_file, ".gltf") ||
              boost::algorithm::iends_with(input_file, ".fbx")) {
-        // These formats always carry material/texture data, so they go through the textured
+        // These formats can carry material/texture data, so they go through the textured
         // import path: the geometry becomes a normal object and the texture is handed to the
         // texture-to-color dialog via Model::texture_mesh.
         auto tex_mesh = std::make_shared<TexturedMesh>();

src/libslic3r/PresetBundle.cpp

@@ -2715,19 +2715,13 @@ void PresetBundle::load_installed_sla_materials(AppConfig &config)
         preset.set_visible_from_appconfig(config);
 }
 
-// Mixed-color filament metadata is project state, carried in the 3mf's project_settings.config.
-// BambuStudio also snapshots it in the app config so the last session's mixes are back before any
-// project is opened; there the filament list itself is a single global snapshot, so the mixed
-// arrays live next to it in the global "presets" section. Orca's per-printer preset memory instead
-// rebuilds the filament list from the selected printer's snapshot (filament_%02u/filament_colors)
-// on startup AND on every printer selection — so the mixed arrays, whose component ids are 1-based
-// indices into exactly that list, must live in the same per-printer snapshot or they end up
-// describing a list they were never saved against (and previously got reset on every printer
-// select, losing the mixes over a restart).
-// Missing keys clear the arrays: a printer with no stored mixes must not inherit another's.
-// fallback_to_global additionally reads the legacy shared "presets" keys (the old format) so a
-// config saved by an earlier build still restores at startup; export_selections clears that
-// section on the next save.
+// Mixed-color filament metadata is project state saved in the 3mf, also mirrored into the app
+// config so the last session's mixes are back before any project is opened. It is kept in the
+// per-printer snapshot next to the filament list it indexes (filament_%02u/filament_colors),
+// because that list is rebuilt on every printer selection and the component ids are 1-based
+// indices into exactly that list. Missing keys clear the arrays, so one printer never inherits
+// another's mixes; fallback_to_global also reads the shared "presets" keys an older config
+// layout used, which export_selections drops on the next save.
 static void load_mixed_filament_settings(DynamicPrintConfig &project_config, AppConfig &config,
                                          const std::string &printer_name, size_t n_filaments,
                                          bool fallback_to_global)
@@ -3162,12 +3156,9 @@ void PresetBundle::export_selections(AppConfig &config)
                                                               "|");
     config.set_printer_setting(printer_name, "flush_multiplier", flush_multiplier_str);
 
-    // Mixed-color filament metadata: stored in the per-printer snapshot next to the filament
-    // list it indexes (filament_%02u / filament_colors), so each printer's remembered config
-    // round-trips its own mixes and re-applying a snapshot never leaves the arrays describing a
-    // different list (see load_mixed_filament_settings). Bools are ','-joined; the
-    // component/ratio/range strings are '|'-joined; the gradient curve is escaped instead,
-    // because its values contain '|'.
+    // Mixed-color filament metadata goes into the per-printer snapshot next to the filament list
+    // it indexes (see load_mixed_filament_settings). Bools are ','-joined and the component, ratio
+    // and range strings '|'-joined; the gradient curve is escaped instead, as it contains '|'.
     auto join_bools = [](const std::vector<unsigned char> &vals) {
         std::string s;
         for (size_t i = 0; i < vals.size(); ++i) {
@@ -3227,8 +3218,7 @@ void PresetBundle::set_num_filaments(unsigned int n, std::vector<std::string> ne
     ams_multi_color_filment.resize(n);
 
     // Mixed-color metadata is a parallel per-filament array set, so it has to grow and shrink
-    // with the filament count exactly like filament_colour above. Missing this leaves the
-    // arrays short and every lookup of a newly created slot reads past the end.
+    // with the filament count exactly like filament_colour above.
     if (auto* opt = project_config.option<ConfigOptionBools>("filament_is_mixed"))
         opt->values.resize(n, false);
     if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_components"))
@@ -3285,8 +3275,7 @@ void PresetBundle::set_num_filaments(unsigned int n, std::string new_color)
     ams_multi_color_filment.resize(n);
 
     // Mixed-color metadata is a parallel per-filament array set, so it has to grow and shrink
-    // with the filament count exactly like filament_colour above. Missing this leaves the
-    // arrays short and every lookup of a newly created slot reads past the end.
+    // with the filament count exactly like filament_colour above.
     if (auto* opt = project_config.option<ConfigOptionBools>("filament_is_mixed"))
         opt->values.resize(n, false);
     if (auto* opt = project_config.option<ConfigOptionStrings>("filament_mixed_components"))

src/libslic3r/Print.cpp

@@ -2615,12 +2615,9 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
             print_object_instances_ordering = sort_object_instances_by_model_order(*this);
             // A mixed slot is virtual; only its components reach a nozzle. These per-object orderings
             // are unsorted (no resolve_mixed_filaments), so expand the slots here for the grouping, the
-            // unprintable sets and the slice-used lists. No-op without mixed filaments.
-            // Orca: the slice-used lists stay sourced from these expanded lists rather than from the
-            // sorted orderings (which may add the wipe-tower filament or seed dontcare layers
-            // differently), so prints without mixed filaments keep their used-filament set; the
-            // first-layer set therefore lists every component of a mixed slot, not just the one layer 0
-            // resolves to.
+            // unprintable sets and the slice-used lists. Because the expansion happens here rather than
+            // on the sorted orderings, the first-layer used set lists every component of a mixed slot,
+            // not just the one layer 0 resolves to. No-op without mixed filaments.
             const auto &is_mixed  = m_config.filament_is_mixed.values;
             const auto &comp_strs = m_config.filament_mixed_components.values;
             const bool  has_mixed = has_any_mixed_filament(is_mixed);

src/libslic3r/PrintApply.cpp

@@ -1931,8 +1931,8 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
             for (const ModelVolume *volume : volumes) {
                 const std::vector<bool> &volume_used_facet_states = volume->mmu_segmentation_facets.get_data().used_states;
 
-                // Sizes may legitimately differ: paint data stored before the state range was
-                // extended carries a shorter used_states vector. Merge over the common prefix.
+                // Paint data saved before the painted state range was extended deserializes a
+                // shorter used_states vector, so merge over the common prefix.
                 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];
             }

src/libslic3r/TextureToColor/TextureToColor.cpp

@@ -639,9 +639,8 @@ static bool repair_cluster_smooth(
     {
         TriangleMesh stats_mesh(static_cast<const indexed_triangle_set&>(mesh));
         const auto& stats = stats_mesh.stats();
-        // Orca's TriangleMeshStats defines manifold() as open_edges == 0 and does not track
-        // non-manifold edges/vertices separately, so BBS's "!manifold() || has_open_edges()"
-        // collapses to this single test and the extra counters drop out of the log.
+        // Orca's TriangleMeshStats only counts open edges: manifold() is open_edges == 0, and
+        // there are no separate non-manifold edge/vertex counters to test or log here.
         if (!stats.manifold()) {
             BOOST_LOG_TRIVIAL(info) << log_prefix << ": mesh has non-manifold geometry or open boundaries, open_edges="
                                     << stats.open_edges;

src/libslic3r/libslic3r.h

@@ -64,10 +64,9 @@ static constexpr double LARGE_BED_THRESHOLD = 2147;
 // Orca: maximum number of extruders is 64. For SEMM printers, it defines maximum filament number.
 static constexpr size_t MAXIMUM_EXTRUDER_NUMBER = 64;
 
-// Orca: how many filament slots syncing an AMS setup may create. This used to follow
-// EnforcerBlockerType::ExtruderMax, which capped it at the number of paintable filaments; that
-// limit has since been raised to 32, so the value is pinned here to keep AMS sync behaving as
-// before for projects that use no mixed-colour filaments.
+// Orca: how many filament slots syncing an AMS setup may create. This was derived from
+// EnforcerBlockerType::ExtruderMax, but that cap now covers 32 paintable filaments, so the AMS
+// limit is pinned here to keep sync behaving as it does for projects without mixed-color filaments.
 static constexpr size_t MAXIMUM_AMS_SYNC_FILAMENT_NUMBER = 16;
 
 // Orca: maximum line width is 5 times the nozzle diameter

src/slic3r/GUI/ConfigManipulation.cpp

@@ -577,13 +577,9 @@ void ConfigManipulation::update_print_fff_config(DynamicPrintConfig* config, con
     }
 
     // BBS
-    // A filament override naming a slot that no longer exists is stale and falls back to the
-    // plater's value. Support and the wipe tower are additionally restricted to physical filaments:
-    // the engine consumes those keys directly, with no per-layer mixed resolution, so a virtual
-    // slot there would reach the G-code unresolved. The per-feature keys have no such restriction —
-    // LayerTools::extruder() and its siblings resolve a mixed slot to the physical filament chosen
-    // for each layer. The sidebar dropdowns already hide mixed slots for the restricted keys
-    // (Plater.cpp DynamicFilamentList); this reset covers values loaded from projects.
+    // Reset filament overrides pointing at a slot that no longer exists. Support and the wipe
+    // tower additionally reject mixed slots: the engine consumes those keys directly, so a virtual
+    // slot would reach the G-code unresolved, while the per-feature keys are resolved per layer.
     static const char* physical_only_keys[] = { "support_filament", "support_interface_filament", "wipe_tower_filament" };
     static const char* feature_keys[] = { "outer_wall_filament_id", "inner_wall_filament_id",
                                           "sparse_infill_filament_id", "internal_solid_filament_id",

src/slic3r/GUI/FilamentBitmapUtils.cpp

@@ -131,8 +131,7 @@ void fill_gradient_ramp_rect(wxDC& dc, const wxRect& rect, const std::vector<wxC
     dc.SetPen(*wxTRANSPARENT_PEN);
     for (int y = 0; y < rect.height; ++y) {
         // Row 0 is the top of the rect and so takes the ramp's last entry, the model's top.
-        // Mapping over height - 1 keeps both ends of the ramp on screen; a swatch is often
-        // shorter than the ramp is long, so truncating either end would be visible.
+        // Mapping over height - 1 puts both ends of the ramp on screen even in a short swatch.
         const double t = (rect.height > 1) ? (double) (rect.height - 1 - y) / (rect.height - 1) : 0.5;
         dc.SetBrush(wxBrush(ramp[static_cast<size_t>(t * (ramp.size() - 1) + 0.5)]));
         dc.DrawRectangle(rect.x, rect.y + y, rect.width, 1);

src/slic3r/GUI/FilamentBitmapUtils.hpp

@@ -38,19 +38,17 @@ wxColour blend_n_colors(const std::vector<wxColour>& cols, const std::vector<dou
 
 // Sample a gradient mixed filament the way the slicer builds it: t runs 0..1 over the
 // model's height, the curve gives the first component's ratio at t, and the two
-// components are blended at that ratio. Entry 0 is the bottom of the model, the last
-// entry its top. Blending goes through blend_n_colors, so measured mixes and the
-// reserved [kGradientMinRatio, kGradientMaxRatio] band are both respected — a plain
-// two-endpoint fade is neither.
+// components are blended at that ratio through blend_n_colors. Entry 0 is the bottom
+// of the model, the last entry its top.
 std::vector<wxColour> sample_gradient_ramp(const wxColour& first,
                                            const wxColour& second,
                                            const Slic3r::GradientCurve& curve,
                                            int steps);
 
 // Same ramp for a project config slot, resolving components, colours and curve (or the
-// linear gradient_range fallback) from cfg. Empty unless the slot is a two-component
-// gradient mixed filament, which is what gates every caller to mixed slots only.
-// steps is the ramp's resolution; pass the destination's height in pixels.
+// linear gradient_range fallback) from cfg. Returns empty for any slot that is not a
+// two-component gradient mixed filament. steps is the ramp's resolution; pass the
+// destination's height in pixels.
 std::vector<wxColour> mixed_gradient_ramp(const Slic3r::DynamicPrintConfig& cfg, size_t slot, int steps);
 
 // Fill rect with a ramp, ramp.front() along the bottom edge.

src/slic3r/GUI/GLCanvas3D.cpp

@@ -9681,10 +9681,9 @@ void GLCanvas3D::_render_paint_toolbar() const
             }
         }
     }
-    // ORCA: the loop above only produces a label for a slot whose preset is found in the preset
-    // collection, while the render loop below iterates extruder_num (= colour count). Pad the
-    // label arrays so a slot without a matching preset cannot index past them — reading a garbage
-    // std::string here crashes in ImGui::CalcTextSize (strlen).
+    // ORCA: the loop above only labels a slot whose preset was found in the preset collection,
+    // while the render loop below iterates extruder_num. Pad the label arrays so a slot without a
+    // matching preset cannot index past them; a garbage std::string crashes ImGui::CalcTextSize.
     while (int(filament_text_first_line.size()) < extruder_num) {
         filament_text_first_line.emplace_back();
         filament_text_second_line.emplace_back();

src/slic3r/GUI/GUI_App.cpp

@@ -8906,9 +8906,9 @@ void GUI_App::load_current_presets(bool active_preset_combox/*= false*/, bool ch
         auto* nozzle_diameter = edited_printer_preset.config.option<ConfigOptionFloats>("nozzle_diameter");
         if (nozzle_diameter) {
             // Mixed-color slots are virtual filaments kept at the tail of the list, so they have no
-            // nozzle of their own. Sizing to the nozzle count alone truncates them away — and this
-            // runs right after a project is loaded, so it would silently drop the project's mixes
-            // and then let update_extruder_count() strip every painted facet above the new count.
+            // nozzle of their own. Sizing to the nozzle count alone would silently drop the mixes of
+            // a just-loaded project, and update_extruder_count() would then strip the facets painted
+            // with them.
             preset_bundle->set_num_filaments(nozzle_diameter->values.size() + preset_bundle->num_mixed_filaments());
         }
     }

src/slic3r/GUI/GUI_ObjectList.cpp

@@ -3234,8 +3234,8 @@ void ObjectList::merge(bool to_multipart_object)
 void ObjectList::layers_editing()
 {
     // Height ranges give each range its own layer height, varying the mixed sub-layer heights just
-    // like an adaptive profile; sibling of the on_action_layersediting/ConfigManipulation warnings,
-    // sharing the same do-not-show-again flag.
+    // like an adaptive profile, so this raises the same warning as variable layer height and shares
+    // its do-not-show-again flag.
     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") {

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.cpp

@@ -326,10 +326,9 @@ bool GLGizmoMmuSegmentation::draw_color_button(int idx, const char* id_str, cons
     bool dark_tone = gradient ? (*gradient)[gradient->size() / 2].GetLuminance() < 0.51 :
                                 (0.299f * color.r() + 0.587f * color.g() + 0.114f * color.b()) < 0.51f; // matching values used by wxWidgets with clr.GetLuminance() < 0.51
 
-    // Paint a gradient mixed filament's fade before the button and keep the button transparent, so the
-    // slot number and the frame below stay on top of it. The bands cannot round their corners, so the
-    // fade is drawn at the frame's inset and the frame masks it into the same shape a plain color slot
-    // gets.
+    // Paint a gradient mixed filament's fade before the button and keep the button transparent, so
+    // the slot number and the frame below stay on top of it. The bands cannot round their corners,
+    // so the fade is inset to the frame, which masks it into the shape a plain color slot gets.
     if (gradient) {
         ImGuiWrapper::draw_gradient_ramp(draw_list, {pos.x + frame_inset * scale, pos.y + frame_inset * scale},
                                          {pos.x + size.x - frame_inset * scale, pos.y + size.y - frame_inset * scale}, *gradient);
@@ -778,7 +777,7 @@ 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);
-        // As above: a mixed-color slot can index past the physical colour list.
+        // A mixed-color slot can index past the physical colour list; fall back to the first colour.
         if (extruder_color_idx >= (int)m_extruders_colors.size())
             extruder_color_idx = 0;
         std::vector<ColorRGBA> ebt_colors;

src/slic3r/GUI/Gizmos/GLGizmoMmuSegmentation.hpp

@@ -142,7 +142,7 @@ private:
     // ORCA
     bool draw_color_button(int idx, const char* id_str, const ColorRGBA& color, ColorRGBA& map_color, bool active, float scale);
     // Gradient ramp of a filament slot, or nullptr when the slot is a plain single color
-    // filament, so callers can index into what they get back freely.
+    // filament. A non-null result is never empty.
     const std::vector<wxColour>* gradient_of(int idx) const
     {
         return idx >= 0 && idx < (int) m_gradient_ramps.size() && !m_gradient_ramps[idx].empty() ? &m_gradient_ramps[idx] : nullptr;

src/slic3r/GUI/Gizmos/GLGizmosManager.cpp

@@ -998,8 +998,8 @@ bool GLGizmosManager::on_key(wxKeyEvent& evt)
                     keyCode = keyCode- WXK_NUMPAD0+'0';
                 }
                 if (keyCode >= '0' && keyCode <= '9') {
-                    // The paint palette now reaches EXTRUDERS_LIMIT (mixed-color filaments share
-                    // the same slots), so any leading digit that can start a valid two-digit
+                    // The paint palette reaches EXTRUDERS_LIMIT slots (mixed-color filaments take
+                    // ordinary slots too), so any leading digit that can start a valid two-digit
                     // number waits briefly for a second one.
                     const int digit        = keyCode - '0';
                     const int shortcut_max = int(GLGizmoMmuSegmentation::EXTRUDERS_LIMIT);

src/slic3r/GUI/GradientCurveEditor.cpp

@@ -19,7 +19,7 @@ namespace GUI {
 wxDEFINE_EVENT(wxEVT_GRADIENT_CURVE_CHANGED, wxCommandEvent);
 
 namespace {
-// Layout (Figma "Property 1=Default", 214.06 x 179.63 px reference).
+// Layout ratios of the plot rect within the widget, taken from a 214 x 180 px reference drawing.
 // Plot rect occupies the upper-left region; right + bottom margins host axis arrows / labels.
 constexpr double kPlotLeftRatio   = 0.0316;
 constexpr double kPlotRightRatio  = 0.6766;
@@ -37,7 +37,7 @@ constexpr int kStrokeAxis       = 2;   // axis line width (px, no DPI scaling -
 constexpr int kAxisArrowHalf    = 5;   // half-base of the axis arrow triangle (DIP)
 constexpr int kAxisArrowLen     = 10;  // length of the axis arrow triangle (DIP)
 
-// Light-mode design tokens from Figma. Resolved through StateColor::darkModeColorFor()
+// Light-mode design tokens. Resolved through StateColor::darkModeColorFor()
 // at paint time so the editor follows the app theme (#EEEEEE -> #4C4C55, #6B6B6B ->
 // #818183, #262E30 -> #EFEFF0, *wxWHITE -> #2D2D31). Don't read these directly in paint;
 // always go through the resolved locals declared at the top of on_paint().
@@ -46,11 +46,9 @@ const wxColour kAxisColor   (107, 107, 107);   // #6B6B6B grey 700
 const wxColour kLabelMuted  (107, 107, 107);   // #6B6B6B grey 700
 const wxColour kLabelStrong ( 38,  46,  48);   // #262E30 grey 900
 
-// LAB (DeltaE76) threshold for "curve color is too close to the background". Below this
-// we paint a subtle axis-color outline so the curve doesn't visually vanish; above this
-// we draw the curve plain. ~15 is "perceptible but still close", looser than the strict
-// 5.0 used by FlushPredict::is_similar_color but loose enough that a pastel pink on white
-// or a charcoal on #2B2B2B still triggers an outline.
+// LAB (DeltaE76) threshold for "curve color is too close to the background": below it the curve
+// gets a subtle outline so it does not visually vanish, otherwise it is drawn plain. Looser than
+// the 5.0 of FlushPredict::is_similar_color, so a pastel pink on white still gets an outline.
 constexpr float kBgSimilarThreshold = 15.0f;
 constexpr int   kOutlineExtraDip    = 2;
 } // namespace
@@ -65,8 +63,6 @@ GradientCurveEditor::GradientCurveEditor(wxWindow* parent,
     SetBackgroundStyle(wxBG_STYLE_PAINT);
     SetBackgroundColour(wxGetApp().get_window_default_clr());
     // Wide enough so the X-axis "Material Ratio" label fits past the arrow tip without overlap.
-    // 260 (was 240): adds room for the "Material Ratio" label that gets shifted right by the
-    // longer axis arrow; the hosting MixedFilamentDialog grows to 470 DIP to accommodate.
     SetMinSize(FromDIP(wxSize(260, 200)));
 
     reset_to_linear(0.10, 0.90);
@@ -456,10 +452,9 @@ void GradientCurveEditor::on_paint(wxPaintEvent& /*evt*/)
         return poly;
     };
 
-    // Only the geometry goes through the graphics context: dc.DrawLines() takes integer
-    // wxPoint and would quantize the curve back to whole pixels.  The pen is still set on
-    // the dc, which forwards it to this same context while keeping the dc's own cached
-    // state in sync, so later dc drawing does not inherit the curve's pen.
+    // Only the geometry goes through the graphics context: dc.DrawLines() takes integer wxPoint
+    // and would quantize the curve back to whole pixels. The pen is still set on the dc, which
+    // forwards it here while keeping its own cached state in sync for later dc drawing.
     auto draw_polyline = [&](const std::vector<wxPoint2DDouble>& poly, const wxColour& col, int stroke_dip) {
         dc.SetPen(wxPen(col, FromDIP(stroke_dip)));
         gc->StrokeLines(poly.size(), poly.data());
@@ -552,12 +547,9 @@ void GradientCurveEditor::on_left_down(wxMouseEvent& evt)
 
     // 4) Selected curve line body hit -> insert a new anchor at cursor x (snapped
     //    to the current smooth curve so the initial click is visually invisible)
-    //    and immediately enter Anchor drag mode. PS Curves style: the drag-bend
-    //    interaction has no separate "bend without anchor" mode; pressing and
-    //    dragging on the line is equivalent to clicking to add then dragging the
-    //    fresh anchor. Trades the previous (failed) "no anchor on drag" promise
-    //    for genuine cursor tracking, since a single cubic between two existing
-    //    anchors mathematically cannot put its peak under an off-center cursor.
+    //    and immediately enter Anchor drag mode. Bending the segment without
+    //    inserting an anchor is not an option: a single cubic between two existing
+    //    anchors cannot put its peak under an off-center cursor.
     double nx = 0, dummy = 0;
     px_to_data(pos.x, pos.y, nx, dummy);
     if (nx <= 0.0 || nx >= 1.0 || seg < 0) {

src/slic3r/GUI/MixedFilamentDialog.cpp

@@ -894,9 +894,9 @@ wxBoxSizer* MixedFilamentDialog::create_ratio_slider()
         on_ratio_changed(std::max(MIN_COMPONENT_RATIO, std::min(100 - MIN_COMPONENT_RATIO, new_ratio)));
     });
 
-    // Release whenever the capture is held, not only when the drag flag is set:
-    // the flag can be cleared behind our back, and a capture that outlives the
-    // widget wedges mouse input for the whole application.
+    // Key the release off the capture itself, not off the drag flag: the two can fall out of
+    // sync (a lost capture clears the flag on its own), and a capture that outlives the widget
+    // wedges mouse input for the whole application.
     m_ratio_bar->Bind(wxEVT_LEFT_UP, [this](wxMouseEvent&) {
         m_ratio_dragging = false;
         if (m_ratio_bar->HasCapture())
@@ -1492,11 +1492,9 @@ void MixedFilamentDialog::on_ratio_changed(int new_ratio_a)
 
 void MixedFilamentDialog::on_gradient_toggled()
 {
-    // Orca: the engine only produces a gradient when the print profile's
-    // "enable_mixed_color_sublayer" option is on (ToolOrdering::resolve_mixed_filaments
-    // falls back to whole-layer round-robin without it, and BBS leaves users to find the
-    // option themselves). Offer to switch it on so the gradient the user just enabled
-    // actually shows up in the sliced result. Keep this block on future BBS syncs.
+    // Orca: a gradient is only sliced when the print profile's "enable_mixed_color_sublayer"
+    // option is on; without it ToolOrdering picks a single component per whole layer. Offer to
+    // turn the option on instead of silently ignoring the gradient the user just enabled.
     bool checked = m_chk_gradient->GetValue();
 
     if (checked) {

src/slic3r/GUI/PartPlate.cpp

@@ -2048,13 +2048,8 @@ bool PartPlate::check_tpu_printable_status(const DynamicPrintConfig & config, co
 }
 
 // A mixed-color filament alternates between its components constantly. On a single-nozzle
-// printer every one of those switches is a full filament change plus a purge, so warn the
-// user before they commit to it. Printers with more than one nozzle can keep the components
-// loaded simultaneously and are not affected.
-//
-// BBS additionally excludes its H2C/H2D/X2D models by name; those are multi-nozzle machines
-// already ruled out by the nozzle_diameter test above, so the name check is dropped here
-// rather than carried over as a Bambu-specific special case.
+// printer every one of those switches is a full filament change plus a purge, so warn before
+// slicing. Multi-nozzle printers keep the components loaded at once and are not affected.
 bool PartPlate::check_single_extruder_mixed_filament_risk(const DynamicPrintConfig &config, std::string &warning_text) const
 {
     warning_text.clear();

src/slic3r/GUI/PlateSettingsDialog.cpp

@@ -473,8 +473,7 @@ PlateSettingsDialog::PlateSettingsDialog(wxWindow* parent, const wxString& title
     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.
+    // filament order cannot be honoured; grey out the choice and explain that in the dialog.
     {
         auto &proj_cfg     = wxGetApp().preset_bundle->project_config;
         auto *is_mixed_opt = proj_cfg.option<ConfigOptionBools>("filament_is_mixed");

src/slic3r/GUI/Plater.cpp

@@ -3876,10 +3876,8 @@ void Sidebar::change_top_border_for_mode_sizer(bool increase_border)
 
 
 // ---- Mixed-color filament sidebar support ----
-// Ported from BambuStudio's 混色耗材 feature. BBS hosts these widgets in an
-// m_filament_area_wrapper that Orca's sidebar has no counterpart for, so the mixed
-// section is parented to p->scrolled and sized with Orca's own row-height preference
-// (filaments_area_preferred_count) rather than BBS's fixed 3-row / 12-filament cap.
+// The mixed rows get their own scroll area, capped by Orca's filaments_area_preferred_count
+// row budget rather than BBS's fixed 3-row / 12-filament limit.
 void Sidebar::recalc_filament_scroll_sizes()
 {
     if (!p->m_mixed_scroll_area || !p->m_mixed_scroll_area->GetSizer())
@@ -4102,8 +4100,8 @@ void Sidebar::update_mixed_filament_list()
             unsigned int mix_num = (unsigned int)(cfg_idx + 1);
 
             // The swatch fades bottom to top over the model's height, sampled the same way
-            // the slicer builds the sublayers, so it matches the editor's Effect Preview. It
-            // comes back empty for every slot that is not a two component gradient mix.
+            // the slicer builds the sublayers, so it matches the editor's Effect Preview. The
+            // ramp comes back empty for every slot that is not a two component gradient mix.
             const int swatch_sz = FromDIP(20);
             const std::vector<wxColour> gradient_ramp = mixed_gradient_ramp(project_config, cfg_idx, swatch_sz);
 
@@ -4642,9 +4640,8 @@ static bool create_mixed_filament_from_result(
         multi_colour_opt->values[new_idx] = mixed_color;
     }
 
-    // set_num_filaments() above is what grows these parallel arrays. Guard the writes anyway,
-    // matching the gradient writes below, so a sizing bug degrades into a no-op rather than a
-    // heap overwrite.
+    // set_num_filaments() above already grows these parallel arrays; the writes are still
+    // size-guarded so a sizing bug degrades into a no-op rather than a heap overwrite.
     {
         auto* is_mixed_opt = project_config.option<ConfigOptionBools>("filament_is_mixed");
         while (is_mixed_opt->values.size() <= new_idx) is_mixed_opt->values.push_back(false);
@@ -14071,11 +14068,9 @@ 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. All three
-    // sites (with ObjectList::layers_editing for height ranges) honour the same do-not-show-again flag.
+    // Sub-layer splitting divides each layer by the mix ratio, so a variable layer height profile
+    // makes those sub-layer heights uneven and degrades the blend. ConfigManipulation warns for the
+    // opposite order, when the option is switched on while a variable profile already exists.
     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")) {
@@ -19988,14 +19983,11 @@ std::vector<std::string> Plater::get_filament_color_render_type() const
 
 const std::vector<std::vector<wxColour>>& Plater::get_filament_gradient_ramps() const
 {
-    // Sampling a ramp walks the measured-blend recipe table once per step, and the paint toolbar
-    // asks for the ramps on every rendered frame, so they are cached against the config values
-    // they are built from and resampled only when one of those actually changes.
-    //
-    // The cache cannot live on the Plater: the extruder icons ask for the ramps from inside
-    // MenuFactory::init(), which runs while this Plater is still being constructed, so `this` is
-    // not usable yet. Everything the ramps are built from is global anyway, and there is one
-    // Plater per process, which is the same reasoning behind the icons' own static BitmapCache.
+    // Sampling a ramp walks the measured-blend recipe table once per step and the paint toolbar
+    // asks for the ramps every rendered frame, so they are cached against the config values they
+    // are built from. The cache is static rather than a Plater member because the extruder icons
+    // ask for the ramps from MenuFactory::init(), which runs while this Plater is still inside its
+    // own constructor, so wxGetApp().plater_ is not assigned yet.
     static std::string                        s_ramps_key;
     static std::vector<std::vector<wxColour>> s_ramps;
 

src/slic3r/GUI/SyncAmsInfoDialog.cpp

@@ -2577,7 +2577,7 @@ void SyncAmsInfoDialog::reset_and_sync_ams_list()
     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.
+    // AMS sync targets.
     auto* is_mixed_opt = preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed");
 
     bool use_double_extruder = get_is_double_extruder();
@@ -2801,7 +2801,7 @@ void SyncAmsInfoDialog::generate_override_fix_ams_list()
     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.
+    // AMS sync targets.
     auto* is_mixed_opt = preset_bundle->project_config.option<ConfigOptionBools>("filament_is_mixed");
 
     bool use_double_extruder = get_is_double_extruder();

src/slic3r/GUI/TextureImportDialog.cpp

@@ -1368,11 +1368,9 @@ void TexturePreviewCanvas::ensure_gl_ready()
 {
     if (m_gl_initialized) return;
 
-    // BBS loads GL entry points here with GLEW. Orca uses glad and centralises loading in
-    // OpenGLManager, which has already run by the time any canvas is realized, so just
-    // verify the loader is up and drain any stale error state.
-    // glad leaves unresolved entry points as null pointers, so this is a cheap guard against
-    // painting before OpenGLManager::init_gl() has run.
+    // BBS loads the GL entry points here with GLEW; Orca loads them centrally in
+    // OpenGLManager, so only check that this has already happened (glad leaves unresolved
+    // entry points null) and drain any stale error state.
     if (glGetString == nullptr) {
         BOOST_LOG_TRIVIAL(error) << "TexturePreviewCanvas: OpenGL functions are not loaded yet";
         return;
@@ -2436,10 +2434,9 @@ void TextureImportDialog::start_computation(bool auto_color, bool initial)
     settings.target_colors_num = auto_color ? 0 : (size_t)m_param_color_count;
     settings.smooth_weight     = m_param_smooth / 10.0;
     settings.mesh_repair_decision = m_mesh_repair_decision;
-    // BBS repairs the mesh through the Windows 3D SDK, which only exists on Windows and only
-    // when the SDK is present at build time. Orca already ships a CGAL-based repair
-    // (MeshBoolean::cgal::repair) that works on all three platforms, so use that instead —
-    // this makes the repair path available on Linux and macOS too.
+    // BBS repairs the mesh through the Windows 3D SDK, which is only available on Windows
+    // builds that ship the SDK. Orca's CGAL-based repair (MeshBoolean::cgal::repair) works
+    // on all three platforms, so use that instead.
     settings.mesh_repair_callback = [](const indexed_triangle_set& mesh,
                                        indexed_triangle_set&       repaired_mesh,
                                        std::function<void(const char*, unsigned)> progress_callback,

src/slic3r/GUI/Widgets/DropDown.cpp

@@ -360,8 +360,7 @@ void DropDown::render(wxDC &dc)
     for (int i = 0; i < items.size(); ++i) {
         auto &item = items[i];
         int states2 = states;
-        // Dimmed items stay selectable but render greyed out (used by the mixed-filament
-        // dialog to show components that are already consumed by another mix).
+        // Dimmed items render greyed out but stay selectable, so they cannot reuse the disabled state.
         bool is_dimmed = (item.style & DD_ITEM_STYLE_DIMMED) != 0;
         if ((item.style & DD_ITEM_STYLE_DISABLED) != 0)
             states2 &= ~StateColor::Enabled;

src/slic3r/GUI/WipeTowerDialog.cpp

@@ -261,10 +261,9 @@ static std::vector<float> MatrixFlatten(const WipingDialog::VolumeMatrix& matrix
     return vec;
 }
 
-// Mixed-color slots are virtual: they are never loaded into a tray and so have no flushing
-// volumes of their own. The dialog therefore shows only the physical filaments, which means
-// converting between the full config matrix (indexed by config slot) and a dense physical
-// sub-matrix (indexed by row/column in the table).
+// Mixed-color slots are virtual and have no flushing volumes, so the dialog shows only the
+// physical filaments. That means converting between the full config matrix (indexed by config
+// slot) and a dense physical sub-matrix (indexed by row/column in the table).
 static std::vector<double> extract_physical_sub_matrix(
     const std::vector<double>& full_matrix, size_t full_n,
     const std::vector<size_t>& indices)

tests/fff_print/test_mixed_filament.cpp

@@ -37,7 +37,7 @@ DynamicPrintConfig mixed_config(bool sublayer_on, const char *ratios = "0.6,0.4"
     return config;
 }
 
-// Total sub-layer groups and per-layer DRR resolutions across the whole tool ordering.
+// Total sub-layer groups and per-layer mixed-filament resolutions across the whole tool ordering.
 void count_mixed(ToolOrdering &to, size_t &groups, size_t &resolutions)
 {
     groups = resolutions = 0;
@@ -139,9 +139,8 @@ TEST_CASE("Whole-layer mixing emits only the nominal layer height", "[MixedFilam
 
 TEST_CASE("By-object prints without mixed filaments keep their used-filament set", "[MixedFilament]")
 {
-    // Regression guard for the mixed gate: with no mixed slot the by-object bookkeeping must
-    // be untouched by this change. Object 2 prints with filament 2, so both filaments are used
-    // and no mixed filament is reported.
+    // With no mixed slot the by-object bookkeeping stays plain: object 2 prints with filament 2,
+    // so both filaments are used and no mixed filament is reported.
     DynamicPrintConfig config = multifilament_config(2, {{"print_sequence", "by object"}});
     const std::vector<std::vector<ConfigBase::SetDeserializeItem>> overrides{ {}, { {"extruder", "2"} } };
 

tests/libslic3r/test_3mf.cpp

@@ -501,10 +501,8 @@ SCENARIO("Nozzle-group metadata .3mf round-trip", "[3mf][MultiNozzle]") {
 
 
 // A mixed-color filament occupies an ordinary filament slot, and painting with it stores an
-// ordinary extruder state — a project saved by BambuStudio encodes filament 5 of a 5-slot setup
-// as paint state 5, with the mix described by the parallel filament_mixed_* project arrays. This
-// pins both halves of that contract at the .3mf layer: the project keys and the painted states
-// must come back exactly as written.
+// ordinary extruder state: a project saved by BambuStudio encodes filament 5 of a 5-slot setup
+// as paint state 5, with the mix described by the parallel filament_mixed_* project arrays.
 SCENARIO("Mixed-color filament setup and painting round-trip through a .3mf", "[3mf][MixedFilament]") {
     GIVEN("a painted model whose project config describes a mixed filament in the last slot") {
         Model model;

tests/libslic3r/test_filament_mixer.cpp

@@ -101,10 +101,9 @@ TEST_CASE("check_mixed_filament_type_consistency flags mismatched component type
 
 TEST_CASE("a support-flagged component reads as its own filament type for the consistency check", "[FilamentMixer]")
 {
-    // Sidebar::update_mixed_filament_list and Sidebar::has_broken_mixed_filament derive each
-    // component's type through DynamicPrintConfig::get_filament_type, which folds the
-    // filament_is_support flag into the type — so toggling that flag alone changes the verdict
-    // and Plater::on_config_change has to refresh the mixed list on filament_is_support too.
+    // The sidebar derives each component's type through DynamicPrintConfig::get_filament_type,
+    // which folds filament_is_support into the type, so toggling that flag alone flips the
+    // verdict and the mixed filament list has to be refreshed on filament_is_support too.
     DynamicPrintConfig plain_pla;
     plain_pla.set_key_value("filament_type", new ConfigOptionStrings({"PLA"}));
     plain_pla.set_key_value("filament_is_support", new ConfigOptionBools({false}));
@@ -193,8 +192,8 @@ TEST_CASE("blend_color_multi weights components", "[FilamentMixer]")
     }
 
     SECTION("Mixing a color with itself stays close to that color") {
-        // The mixer is a degree-4 polynomial fit of pigment behaviour, so a round trip through
-        // it is near-identity rather than exact (the model documents a mean Delta-E around 2).
+        // The mixer is a degree-4 polynomial fit of pigment behaviour, so mixing a color with
+        // itself lands near it rather than exactly on it; allow a small per-channel drift.
         std::string mixed = blend_color_multi({"#123456", "#123456"}, {1, 1});
         REQUIRE(mixed.size() == 7);
         auto comp = [](const std::string &hex, int i) {

tests/libslic3r/test_preset_bundle_loading.cpp

@@ -614,12 +614,10 @@ TEST_CASE("set_num_filaments keeps mixed-color arrays in step with the filament
     }
 }
 
-// A mix is described by 1-based indices into the project's filament list. Orca's per-printer
-// preset memory rebuilds that list from the selected printer's snapshot (filament_%02u /
-// filament_colors) at startup and on every printer selection, so the mixed arrays must be stored
-// in the SAME per-printer snapshot: kept globally (as BambuStudio does — its filament list is a
-// single global snapshot too) they end up indexing a list they were never saved against, and used
-// to be reset on every printer selection instead, losing the mixes over an app restart.
+// A mix is described by 1-based indices into the project's filament list, which Orca rebuilds
+// from the selected printer's snapshot (filament_%02u / filament_colors) at startup and on every
+// printer selection. Held anywhere but that same per-printer snapshot, the mixed arrays end up
+// indexing a filament list they were never saved against.
 TEST_CASE("Mixed-color filament metadata is snapshotted per printer, with its filament list", "[Preset][Bundle][FilamentMixer]")
 {
     PresetBundle bundle;
@@ -674,10 +672,9 @@ TEST_CASE("A multi-point gradient curve survives the app-config snapshot", "[Pre
 }
 
 // A multi-tool printer sizes the filament list from its nozzle count. Mixed-color slots are extra
-// virtual filaments at the tail of that list with no nozzle of their own, so the sync has to add
-// them on top. Sizing to the nozzle count alone truncates them — and because that sync runs right
-// after a project is loaded, it silently drops the project's mixes and then lets the filament-count
-// change strip every painted facet above the new count.
+// virtual filaments at the tail of that list with no nozzle of their own, so the count has to
+// allow for them: sizing to the nozzle count alone drops the project's mixes and strips every
+// painted facet above the new count.
 TEST_CASE("Sizing the filament list to a multi-tool nozzle count keeps mixed slots", "[Preset][Bundle][FilamentMixer]")
 {
     // The 5-slot layout of a 4-tool project carrying one mix of filaments 2 and 3.

tests/libslic3r/test_triangle_selector.cpp

@@ -99,7 +99,7 @@ TEST_CASE("Extruder states above 17 are encoded in a second nibble", "[TriangleS
 }
 
 // Model.cpp writes these hex strings into the 3MF for colored mesh imports; the selector must
-// decode exactly the states that table assigns to them.
+// decode exactly the states CONST_FILAMENTS assigns to them.
 TEST_CASE("Extruder states match the CONST_FILAMENTS hex encoding", "[TriangleSelector]")
 {
     struct Case { const char *hex; int state; };

tests/slic3rutils/test_filament_bitmap_utils.cpp

@@ -140,8 +140,8 @@ TEST_CASE("recompute_mixed_slot_colors honours the configured ratios and is idem
 // --- mixed_gradient_ramp / sample_gradient_ramp -----------------------------------------
 //
 // The ramp is what every mixed filament swatch is drawn from, so these pin the three things
-// a plain two-endpoint fade got wrong: the reserved ratio band, the component order, and the
-// custom curve.
+// a plain fade between two endpoint colours cannot express: the reserved ratio band, the
+// component order, and the custom curve.
 
 namespace {
 
@@ -169,7 +169,7 @@ TEST_CASE("mixed_gradient_ramp runs bottom to top and never reaches a pure compo
     REQUIRE(ramp.size() == 16);
 
     // Neither end is the pure component colour - the slicer clamps the blend to
-    // [kGradientMinRatio, kGradientMaxRatio], which is exactly what a two-endpoint fade missed.
+    // [kGradientMinRatio, kGradientMaxRatio], which a fade between the pure colours would ignore.
     REQUIRE(ramp.front() != wxColour(255, 0, 0));
     REQUIRE(ramp.back() != wxColour(0, 0, 255));
 
@@ -188,7 +188,7 @@ TEST_CASE("mixed_gradient_ramp follows the range's direction rather than the com
     REQUIRE(falling.size() == 16);
 
     // "0.1,0.9" starts blue-heavy at the bottom; "0.9,0.1" starts red-heavy. Reversing the
-    // range must reverse the ramp, which HSV-sorted endpoint colours could not express.
+    // range must reverse the ramp, which endpoint colours ordered by HSV cannot express.
     REQUIRE(int(rising.front().Blue()) > int(rising.front().Red()));
     REQUIRE(int(falling.front().Red()) > int(falling.front().Blue()));
     require_same_rgb(rising.front(), falling.back());