Organic Supports: support_tree_branch_diameter_double_wall

to control when the 2nd wall kicks in.

src/libslic3r/Preset.cpp

@@ -444,7 +444,8 @@ static std::vector<std::string> s_Preset_print_options {
     "support_material_interface_pattern", "support_material_interface_spacing", "support_material_interface_contact_loops", 
     "support_material_contact_distance", "support_material_bottom_contact_distance",
     "support_material_buildplate_only", 
-    "support_tree_angle", "support_tree_angle_slow", "support_tree_branch_diameter", "support_tree_branch_diameter_angle", "support_tree_top_rate", "support_tree_branch_distance", "support_tree_tip_diameter",
+    "support_tree_angle", "support_tree_angle_slow", "support_tree_branch_diameter", "support_tree_branch_diameter_angle", "support_tree_branch_diameter_double_wall", 
+    "support_tree_top_rate", "support_tree_branch_distance", "support_tree_tip_diameter",
     "dont_support_bridges", "thick_bridges", "notes", "complete_objects", "extruder_clearance_radius",
     "extruder_clearance_height", "gcode_comments", "gcode_label_objects", "output_filename_format", "post_process", "gcode_substitutions", "perimeter_extruder",
     "infill_extruder", "solid_infill_extruder", "support_material_extruder", "support_material_interface_extruder",

src/libslic3r/PrintConfig.cpp

@@ -2939,6 +2939,18 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionFloat(5));
 
+    def = this->add("support_tree_branch_diameter_double_wall", coFloat);
+    def->label = L("Branch Diameter with double walls");
+    def->category = L("Support material");
+    // TRN PrintSettings: "Organic supports" > "Branch Diameter"
+    def->tooltip = L("Branches with area larger than the area of a circle of this diameter will be printed with double walls for stability. "
+                     "Set this value to zero for no double walls.");
+    def->sidetext = L("mm");
+    def->min = 0;
+    def->max = 100.f;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloat(3));
+
     // Tree Support Branch Distance
     // How far apart the branches need to be when they touch the model. Making this distance small will cause 
     // the tree support to touch the model at more points, causing better overhang but making support harder to remove.

src/libslic3r/PrintConfig.hpp

@@ -554,6 +554,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloat,               support_tree_angle_slow))
     ((ConfigOptionFloat,               support_tree_branch_diameter))
     ((ConfigOptionFloat,               support_tree_branch_diameter_angle))
+    ((ConfigOptionFloat,               support_tree_branch_diameter_double_wall))
     ((ConfigOptionPercent,             support_tree_top_rate))
     ((ConfigOptionFloat,               support_tree_branch_distance))
     ((ConfigOptionFloat,               support_tree_tip_diameter))

src/libslic3r/PrintObject.cpp

@@ -712,6 +712,7 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "support_tree_angle_slow"
             || opt_key == "support_tree_branch_diameter"
             || opt_key == "support_tree_branch_diameter_angle"
+            || opt_key == "support_tree_branch_diameter_double_wall"
             || opt_key == "support_tree_top_rate"
             || opt_key == "support_tree_branch_distance"
             || opt_key == "support_tree_tip_diameter"

src/libslic3r/Support/SupportCommon.cpp

@@ -537,7 +537,8 @@ static Polylines draw_perimeters(const ExPolygon &expoly, double clip_length)
 static inline void tree_supports_generate_paths(
     ExtrusionEntitiesPtr    &dst,
     const Polygons          &polygons,
-    const Flow              &flow)
+    const Flow              &flow, 
+    const SupportParameters &support_params)
 {
     // Offset expolygon inside, returns number of expolygons collected (0 or 1).
     // Vertices of output paths are marked with Z = source contour index of the expoly.
@@ -634,21 +635,21 @@ static inline void tree_supports_generate_paths(
     ClipperLib_Z::Paths anchor_candidates;
     for (ExPolygon& expoly : closing_ex(polygons, float(SCALED_EPSILON), float(SCALED_EPSILON + 0.5 * flow.scaled_width()))) {
         std::unique_ptr<ExtrusionEntityCollection> eec;
-        double area = expoly.area();
-        if (area > sqr(scaled<double>(5.))) {
-            eec = std::make_unique<ExtrusionEntityCollection>();
-            // Don't reoder internal / external loops of the same island, always start with the internal loop.
-            eec->no_sort = true;
-            // Make the tree branch stable by adding another perimeter.
-            ExPolygons level2 = offset2_ex({ expoly }, -1.5 * flow.scaled_width(), 0.5 * flow.scaled_width());
-            if (level2.size() == 1) {
-                Polylines polylines;
-                extrusion_entities_append_paths(eec->entities, draw_perimeters(expoly, clip_length), ExtrusionRole::SupportMaterial, flow.mm3_per_mm(), flow.width(), flow.height(),
-                    // Disable reversal of the path, always start with the anchor, always print CCW.
-                    false);
-                expoly = level2.front();
+        if (support_params.tree_branch_diameter_double_wall_area_scaled > 0)
+            if (double area = expoly.area(); area > support_params.tree_branch_diameter_double_wall_area_scaled) {
+                eec = std::make_unique<ExtrusionEntityCollection>();
+                // Don't reoder internal / external loops of the same island, always start with the internal loop.
+                eec->no_sort = true;
+                // Make the tree branch stable by adding another perimeter.
+                ExPolygons level2 = offset2_ex({ expoly }, -1.5 * flow.scaled_width(), 0.5 * flow.scaled_width());
+                if (level2.size() == 1) {
+                    Polylines polylines;
+                    extrusion_entities_append_paths(eec->entities, draw_perimeters(expoly, clip_length), ExtrusionRole::SupportMaterial, flow.mm3_per_mm(), flow.width(), flow.height(),
+                        // Disable reversal of the path, always start with the anchor, always print CCW.
+                        false);
+                    expoly = level2.front();
+                }
             }
-        }
 
         // Try to produce one more perimeter to place the seam anchor.
         // First genrate a 2nd perimeter loop as a source for anchor candidates.
@@ -1531,7 +1532,7 @@ void generate_support_toolpaths(
                         support_params.with_sheath, false);
                 }
                 if (! tree_polygons.empty())
-                    tree_supports_generate_paths(support_layer.support_fills.entities, tree_polygons, flow);
+                    tree_supports_generate_paths(support_layer.support_fills.entities, tree_polygons, flow, support_params);
             }
 
             Fill *filler = filler_interface.get();
@@ -1790,7 +1791,7 @@ void generate_support_toolpaths(
                     sheath  = true;
                     no_sort = true;
                 } else if (config.support_material_style == SupportMaterialStyle::smsOrganic) {
-                    tree_supports_generate_paths(base_layer.extrusions, base_layer.polygons_to_extrude(), flow);
+                    tree_supports_generate_paths(base_layer.extrusions, base_layer.polygons_to_extrude(), flow, support_params);
                     done = true;
                 }
                 if (! done)

src/libslic3r/Support/SupportParameters.cpp

@@ -137,6 +137,8 @@ SupportParameters::SupportParameters(const PrintObject &object)
         assert(slicing_params.interface_raft_layers == 0);
         assert(slicing_params.raft_layers() == 0);
     }
+
+    this->tree_branch_diameter_double_wall_area_scaled = 0.25 * sqr(scaled<double>(object_config.support_tree_branch_diameter_double_wall.value)) * M_PI;
 }
 
 } // namespace Slic3r

src/libslic3r/Support/SupportParameters.hpp

@@ -77,6 +77,8 @@ struct SupportParameters {
     InfillPattern 			contact_fill_pattern;
     // Shall the sparse (base) layers be printed with a single perimeter line (sheath) for robustness?
     bool                    with_sheath;
+    // Branches of organic supports with area larger than this threshold will be extruded with double lines.
+    double                  tree_branch_diameter_double_wall_area_scaled;
 
     float 					raft_angle_1st_layer;
     float 					raft_angle_base;

src/slic3r/GUI/ConfigManipulation.cpp

@@ -291,7 +291,8 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig* config)
                                      (config->opt_bool("support_material") || 
                                       config->opt_int("support_material_enforce_layers") > 0);
     for (const std::string& key : { "support_tree_angle", "support_tree_angle_slow", "support_tree_branch_diameter",
-                                    "support_tree_branch_diameter_angle", "support_tree_tip_diameter", "support_tree_branch_distance", "support_tree_top_rate" })
+                                    "support_tree_branch_diameter_angle", "support_tree_branch_diameter_double_wall", 
+                                    "support_tree_tip_diameter", "support_tree_branch_distance", "support_tree_top_rate" })
         toggle_field(key, has_organic_supports);
 
     for (auto el : { "support_material_bottom_interface_layers", "support_material_interface_spacing", "support_material_interface_extruder",

src/slic3r/GUI/Tab.cpp

@@ -1536,6 +1536,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("support_tree_angle_slow", category_path + "tree_angle_slow");
         optgroup->append_single_option_line("support_tree_branch_diameter", category_path + "tree_branch_diameter");
         optgroup->append_single_option_line("support_tree_branch_diameter_angle", category_path + "tree_branch_diameter_angle");
+        optgroup->append_single_option_line("support_tree_branch_diameter_double_wall", category_path + "tree_branch_diameter_double_wall");
         optgroup->append_single_option_line("support_tree_tip_diameter", category_path + "tree_tip_diameter");
         optgroup->append_single_option_line("support_tree_branch_distance", category_path + "tree_branch_distance");
         optgroup->append_single_option_line("support_tree_top_rate", category_path + "tree_top_rate");