Reverse on odd - internal only

src/libslic3r/PerimeterGenerator.cpp

@@ -1404,7 +1404,7 @@ void PerimeterGenerator::apply_extra_perimeters(ExPolygons &infill_area)
 }
 
 // Reorient loop direction
-static void reorient_perimeters(ExtrusionEntityCollection &entities, bool steep_overhang_contour, bool steep_overhang_hole)
+static void reorient_perimeters(ExtrusionEntityCollection &entities, bool steep_overhang_contour, bool steep_overhang_hole, bool reverse_internal_only)
 {
     if (steep_overhang_hole || steep_overhang_contour) {
         for (auto entity : entities) {
@@ -1413,7 +1413,17 @@ static void reorient_perimeters(ExtrusionEntityCollection &entities, bool steep_
                 // Only reverse when needed
                 bool need_reverse = ((eloop->loop_role() & elrHole) == elrHole) ? steep_overhang_hole : steep_overhang_contour;
 
-                if (need_reverse && eloop[0].role()!=erExternalPerimeter) {
+                bool isExternal = false;
+                if(reverse_internal_only){
+                    for(auto path : eloop->paths){
+                        if(path.role() == erExternalPerimeter){
+                            isExternal = true;
+                            break;
+                        }
+                    }
+                }
+
+                if (need_reverse && !isExternal) {
                     eloop->make_clockwise();
                 }
             }
@@ -1711,7 +1721,7 @@ void PerimeterGenerator::process_classic()
             bool steep_overhang_contour = false;
             bool steep_overhang_hole    = false;
             ExtrusionEntityCollection entities = traverse_loops(*this, contours.front(), thin_walls, steep_overhang_contour, steep_overhang_hole);
-            reorient_perimeters(entities, steep_overhang_contour, steep_overhang_hole);
+            reorient_perimeters(entities, steep_overhang_contour, steep_overhang_hole, this->config->overhang_reverse_internal_only);
 
             // if brim will be printed, reverse the order of perimeters so that
             // we continue inwards after having finished the brim
@@ -2233,7 +2243,7 @@ void PerimeterGenerator::process_arachne()
         bool steep_overhang_contour = false;
         bool steep_overhang_hole    = false;
         if (ExtrusionEntityCollection extrusion_coll = traverse_extrusions(*this, ordered_extrusions, steep_overhang_contour, steep_overhang_hole); !extrusion_coll.empty()) {
-            reorient_perimeters(extrusion_coll, steep_overhang_contour, steep_overhang_hole);
+            reorient_perimeters(extrusion_coll, steep_overhang_contour, steep_overhang_hole, this->config->overhang_reverse_internal_only);
             this->loops->append(extrusion_coll);
         }
 

src/libslic3r/Preset.cpp

@@ -726,7 +726,7 @@ bool Preset::has_cali_lines(PresetBundle* preset_bundle)
 static std::vector<std::string> s_Preset_print_options {
     "layer_height", "initial_layer_print_height", "wall_loops", "slice_closing_radius", "spiral_mode", "slicing_mode",
     "top_shell_layers", "top_shell_thickness", "bottom_shell_layers", "bottom_shell_thickness",
-    "extra_perimeters_on_overhangs", "ensure_vertical_shell_thickness", "reduce_crossing_wall", "detect_thin_wall", "detect_overhang_wall", "overhang_reverse", "overhang_reverse_threshold",
+    "extra_perimeters_on_overhangs", "ensure_vertical_shell_thickness", "reduce_crossing_wall", "detect_thin_wall", "detect_overhang_wall", "overhang_reverse", "overhang_reverse_threshold","overhang_reverse_internal_only",
     "seam_position", "staggered_inner_seams", "wall_infill_order", "sparse_infill_density", "sparse_infill_pattern", "top_surface_pattern", "bottom_surface_pattern",
     "infill_direction",
     "minimum_sparse_infill_area", "reduce_infill_retraction","internal_solid_infill_pattern",

src/libslic3r/PrintConfig.cpp

@@ -843,6 +843,14 @@ void PrintConfigDef::init_fff_params()
     def->tooltip = L("Extrude perimeters that have a part over an overhang in the reverse direction on odd layers. This alternating pattern can drastically improve steep overhang.");
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("overhang_reverse_internal_only", coBool);
+    def->label = L("Reverse only internal perimeters");
+    def->full_label = L("Reverse only internal perimeters");
+    def->category = L("Quality");
+    def->tooltip = L("Apply the reverse perimeters logic only on internal perimeters. This reduces the effectiveness of the setting somewhat; however it prevents artefacts on the external walls caused by inaccuracies in the motion system.\nIt may also help to reduce part warping due to lower part stresses.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
 
     def = this->add("overhang_reverse_threshold", coFloatOrPercent);
     def->label = L("Reverse threshold");

src/libslic3r/PrintConfig.hpp

@@ -877,6 +877,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloatOrPercent,       hole_to_polyhole_threshold))
     ((ConfigOptionBool,                 hole_to_polyhole_twisted))
     ((ConfigOptionBool,                 overhang_reverse))
+    ((ConfigOptionBool,                 overhang_reverse_internal_only))
     ((ConfigOptionFloatOrPercent,       overhang_reverse_threshold))
 )
 

src/libslic3r/PrintObject.cpp

@@ -1097,6 +1097,7 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "fuzzy_skin_point_distance"
             || opt_key == "detect_overhang_wall"
             || opt_key == "overhang_reverse"
+            || opt_key == "overhang_reverse_internal_only"
             || opt_key == "overhang_reverse_threshold"
             //BBS
             || opt_key == "enable_overhang_speed"

src/slic3r/GUI/ConfigManipulation.cpp

@@ -736,6 +736,7 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, co
     bool allow_overhang_reverse   = has_detect_overhang_wall && !has_spiral_vase;
     toggle_field("overhang_reverse", allow_overhang_reverse);
     toggle_line("overhang_reverse_threshold", allow_overhang_reverse && has_overhang_reverse);
+    toggle_line("overhang_reverse_internal_only", allow_overhang_reverse && has_overhang_reverse);
     toggle_line("timelapse_type", is_BBL_Printer);
 }
 

src/slic3r/GUI/Tab.cpp

@@ -1911,6 +1911,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("max_travel_detour_distance");
         optgroup->append_single_option_line("extra_perimeters_on_overhangs");
         optgroup->append_single_option_line("overhang_reverse");
+        optgroup->append_single_option_line("overhang_reverse_internal_only");
         optgroup->append_single_option_line("overhang_reverse_threshold");
 
     page = add_options_page(L("Strength"), "empty");