Combine brims option (Prusa style brims) (#12343)

* Union ex brims

Revert "Union ex brims"

This reverts commit bbc9a39faf318dc2df093eb2bdcebf19a4162fe9.

Update Brim.cpp

* dont repeat paths

* Update Brim.cpp

* multimaterial brim independiente

* Normal brim if is by object

* fix print order

* cleaning 1

* cleaning 2

* Normal brim if multimaterial on first layer

* fix artifact

* combine_brim optional

refactoring

* refactoring gcode.cpp

* refactoring brim.cpp

Update Brim.cpp

* Remove multimaterial first-layer check for brims

Stop detecting extruders used on the first layer and remove the is_multimaterial_first_layer guard. Simplify can_combine_brims to only consider combine_brims and whether printing is ByObject, allowing brims to be combined across extruders unless printing by object or combine_brims is disabled. Cleans up unused code and simplifies brim-generation conditions.

* Remove material specification from unified brim comment

* Update PrintConfig.cpp

src/libslic3r/Brim.cpp

@@ -928,16 +928,63 @@ void make_brim(const Print& print, PrintTryCancel try_cancel, Polygons& islands_
     for (size_t iia = 0; iia < islands_area.size(); ++iia)
         islands_area[iia].translate(plate_shift);
 
-    for (auto iter = brimAreaMap.begin(); iter != brimAreaMap.end(); ++iter) {
-        if (!iter->second.empty()) {
-            brimMap.insert(std::make_pair(iter->first, makeBrimInfill(iter->second, print, islands_area)));
-        };
-    }
-    for (auto iter = supportBrimAreaMap.begin(); iter != supportBrimAreaMap.end(); ++iter) {
-        if (!iter->second.empty()) {
-            supportBrimMap.insert(std::make_pair(iter->first, makeBrimInfill(iter->second, print, islands_area)));
-        };
+    const bool combine_brims     = print.config().combine_brims.value;
+    const bool is_by_object      = (print.config().print_sequence == PrintSequence::ByObject);
+    const bool can_combine_brims = combine_brims && !is_by_object;
+
+    if (!can_combine_brims) {
+        // Orca: Generate brims separately for each object when multiple extruders are used
+        for (auto iter = brimAreaMap.begin(); iter != brimAreaMap.end(); ++iter) {
+            if (!iter->second.empty()) {
+                brimMap.insert(std::make_pair(iter->first, makeBrimInfill(iter->second, print, islands_area)));
+            };
+        }
+        for (auto iter = supportBrimAreaMap.begin(); iter != supportBrimAreaMap.end(); ++iter) {
+            if (!iter->second.empty()) {
+                supportBrimMap.insert(std::make_pair(iter->first, makeBrimInfill(iter->second, print, islands_area)));
+            };
+        }
+    } else {
+        // Orca: Unified brim mode (non-sequential printing)
+        ExPolygons            all_brims_merged;
+        std::vector<ObjectID> brim_object_ids;
+
+        // Add all object brims
+        for (auto& [obj_id, brims] : brimAreaMap) {
+            if (!brims.empty()) {
+                expolygons_append(all_brims_merged, brims);
+                brim_object_ids.push_back(obj_id);
+            }
+        }
+
+        if (!all_brims_merged.empty()) {
+            // Merge all brims into a single continuous area
+            all_brims_merged = union_ex(all_brims_merged);
+
+            // Apply a tiny morphological cleanup to reduce boolean-union micro-artifacts.
+            const float brim_cleanup_delta = std::max(float(scaled_resolution), float(SCALED_EPSILON));
+            all_brims_merged = offset2_ex(all_brims_merged, brim_cleanup_delta, -brim_cleanup_delta, jtRound, scaled_resolution);
+
+            // Generate infill once for the merged brim area.
+            ExtrusionEntityCollection merged_brim = makeBrimInfill(all_brims_merged, print, islands_area);
+
+            // In unified mode, assign the merged brim to a deterministic carrier object.
+            // Pick the first object in print order that actually contributed brim area.
+            ObjectID carrier_id;
+            bool     carrier_found = false;
+            for (const auto& [obj_id, _extruder] : objPrintVec) {
+                if (std::find(brim_object_ids.begin(), brim_object_ids.end(), obj_id) != brim_object_ids.end()) {
+                    carrier_id    = obj_id;
+                    carrier_found = true;
+                    break;
+                }
+            }
+
+            if (!carrier_found)
+                carrier_id = brim_object_ids.front();
+
+            brimMap[carrier_id] = std::move(merged_brim);
+        }
     }
 }
-
 } // namespace Slic3r

src/libslic3r/GCode.cpp

@@ -4993,6 +4993,39 @@ LayerResult GCode::process_layer(
     bool has_insert_wrapping_detection_gcode = false;
 
     // Extrude the skirt, brim, support, perimeters, infill ordered by the extruders.
+    // Orca: Print unified global brim before any object.
+    // Only do this if `combine_brims` is enabled and we are printing by layer.
+    if (first_layer && sequence_by_layer && m_config.combine_brims && !print.m_brimMap.empty()) {
+        const ObjectID unified_object_id = [&]() -> ObjectID {
+            ObjectID id;
+            bool     found = false;
+            for (const auto& [obj_id, brim] : print.m_brimMap) {
+                const bool has_printable_entities = std::any_of(brim.entities.begin(), brim.entities.end(),
+                                                                [](const ExtrusionEntity* ee) { return ee != nullptr; });
+                if (!has_printable_entities)
+                    continue;
+                if (found)
+                    return ObjectID();
+                id    = obj_id;
+                found = true;
+            }
+            return found ? id : ObjectID();
+        }();
+
+        if (unified_object_id.valid()) {
+            const auto it = print.m_brimMap.find(unified_object_id);
+            if (it != print.m_brimMap.end()) {
+                this->set_origin(0., 0.);
+                for (const ExtrusionEntity* ee : it->second.entities)
+                    if (ee != nullptr)
+                        gcode += this->extrude_entity(*ee, "brim", m_config.support_speed.value);
+
+                // Mark brim as printed for this object to avoid per-object brim emission later.
+                this->m_objsWithBrim.erase(unified_object_id);
+            }
+        }
+    }
+
     for (unsigned int extruder_id : layer_tools.extruders)
     {
         if (print.config().skirt_type == stCombined && !print.skirt().empty())

src/libslic3r/Preset.cpp

@@ -904,7 +904,7 @@ static std::vector<std::string> s_Preset_print_options {
     "top_surface_speed", "support_speed", "support_object_xy_distance", "support_object_first_layer_gap", "support_interface_speed",
     "bridge_speed", "internal_bridge_speed", "gap_infill_speed", "travel_speed", "travel_speed_z", "initial_layer_speed",
     "outer_wall_acceleration", "initial_layer_acceleration", "top_surface_acceleration", "default_acceleration", "skirt_type", "skirt_loops", "skirt_speed","min_skirt_length", "skirt_distance", "skirt_start_angle", "skirt_height","single_loop_draft_shield", "draft_shield",
-    "brim_width", "brim_object_gap", "brim_use_efc_outline", "brim_type", "brim_ears_max_angle", "brim_ears_detection_length", "enable_support", "support_type", "support_threshold_angle", "support_threshold_overlap","enforce_support_layers",
+    "brim_width", "brim_object_gap", "brim_use_efc_outline", "combine_brims", "brim_type", "brim_ears_max_angle", "brim_ears_detection_length", "enable_support", "support_type", "support_threshold_angle", "support_threshold_overlap","enforce_support_layers",
     "raft_layers", "raft_first_layer_density", "raft_first_layer_expansion", "raft_contact_distance", "raft_expansion",
     "support_base_pattern", "support_base_pattern_spacing", "support_expansion", "support_style",
     // BBS

src/libslic3r/PrintConfig.cpp

@@ -1594,6 +1594,13 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionBool(false));
 
+    def = this->add("combine_brims", coBool);
+    def->label = L("Combine brims");
+    def->category = L("Support");
+    def->tooltip  = L("Combine multiple brims into one when they are close to each other. This can improve brim adhesion.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("brim_ears", coBool);
     def->label = L("Brim ears");
     def->category = L("Support");

src/libslic3r/PrintConfig.hpp

@@ -1550,6 +1550,7 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     ((ConfigOptionString,             thumbnails))
     // BBS: move from PrintObjectConfig
     ((ConfigOptionBool, independent_support_layer_height))
+    ((ConfigOptionBool,               combine_brims))
     // SoftFever
     ((ConfigOptionPercents,            filament_shrink))
     ((ConfigOptionPercents,            filament_shrinkage_compensation_z))