Add options

src/libslic3r/Layer.cpp

@@ -174,6 +174,8 @@ void Layer::make_perimeters()
                         && config.gap_infill_speed.value == other_config.gap_infill_speed.value
                         && config.filter_out_gap_fill.value == other_config.filter_out_gap_fill.value
 		                && config.detect_overhang_wall                   == other_config.detect_overhang_wall
+		                && config.overhang_reverse                       == other_config.overhang_reverse
+		                && config.overhang_reverse_threshold             == other_config.overhang_reverse_threshold
 		                && config.opt_serialize("inner_wall_line_width") == other_config.opt_serialize("inner_wall_line_width")
 		                && config.opt_serialize("outer_wall_line_width") == other_config.opt_serialize("outer_wall_line_width")
 		                && config.detect_thin_wall                  == other_config.detect_thin_wall

src/libslic3r/PerimeterGenerator.cpp

@@ -21,10 +21,6 @@ static const double narrow_loop_length_threshold = 10;
 //we think it's small detail area and will generate smaller line width for it
 static constexpr double SMALLER_EXT_INSET_OVERLAP_TOLERANCE = 0.22;
 
-// Overhang width greater than this will be consider as steep overhang
-// This is a percentage of the extrusion width
-static constexpr double overhang_steep_width = 0.5; // TODO: make this configurable
-
 namespace Slic3r {
 
 // Hierarchy of perimeters.
@@ -221,16 +217,18 @@ static void lowpass_filter_by_paths_overhang_degree(ExtrusionPaths& paths) {
 }
 
 template<class _T>
-static bool detect_steep_overhang(bool               is_contour,
-                                  const BoundingBox &extrusion_bboxs,
-                                  double             extrusion_width,
-                                  const _T           extrusion,
-                                  const ExPolygons  *lower_slices,
-                                  bool              &steep_overhang_contour,
-                                  bool              &steep_overhang_hole)
+static bool detect_steep_overhang(const PrintRegionConfig *config,
+                                  bool                     is_contour,
+                                  const BoundingBox       &extrusion_bboxs,
+                                  double                   extrusion_width,
+                                  const _T                 extrusion,
+                                  const ExPolygons        *lower_slices,
+                                  bool                    &steep_overhang_contour,
+                                  bool                    &steep_overhang_hole)
 {
+    double threshold = config->overhang_reverse_threshold.get_abs_value(extrusion_width);
     // Special case: reverse on every odd layer
-    if (overhang_steep_width < EPSILON) {
+    if (threshold < EPSILON) {
         if (is_contour) {
             steep_overhang_contour = true;
         } else {
@@ -242,8 +240,8 @@ static bool detect_steep_overhang(bool               is_contour,
 
     Polygons lower_slcier_chopped = ClipperUtils::clip_clipper_polygons_with_subject_bbox(*lower_slices, extrusion_bboxs, true);
 
-    // All we need to check is whether we have lines outside `overhang_steep_width`
-    double off = (overhang_steep_width - 0.5) * extrusion_width;
+    // All we need to check is whether we have lines outside `threshold`
+    double off = threshold - 0.5 * extrusion_width;
 
     auto limiton_polygons = offset(lower_slcier_chopped, float(scale_(off)));
 
@@ -270,7 +268,8 @@ static ExtrusionEntityCollection traverse_loops(const PerimeterGenerator &perime
     Polygon                     fuzzified;
 
     // Detect steep overhangs
-    bool overhangs_reverse = perimeter_generator.layer_id % 2 == 1 // Only calculate overhang degree on odd layers
+    bool overhangs_reverse = perimeter_generator.config->overhang_reverse
+                             && perimeter_generator.layer_id % 2 == 1 // Only calculate overhang degree on odd layers
                              && perimeter_generator.config->fuzzy_skin == FuzzySkinType::None; // and not fuzzy skin
 
     for (const PerimeterGeneratorLoop &loop : loops) {
@@ -331,7 +330,7 @@ static ExtrusionEntityCollection traverse_loops(const PerimeterGenerator &perime
             // Skip the check if we already found steep overhangs
             bool found_steep_overhang = (loop.is_contour && steep_overhang_contour) || (!loop.is_contour && steep_overhang_hole);
             if (overhangs_reverse && !found_steep_overhang) {
-                detect_steep_overhang(loop.is_contour, bbox, extrusion_width, Polygons{polygon}, perimeter_generator.lower_slices,
+                detect_steep_overhang(perimeter_generator.config, loop.is_contour, bbox, extrusion_width, Polygons{polygon}, perimeter_generator.lower_slices,
                                       steep_overhang_contour, steep_overhang_hole);
             }
 
@@ -627,7 +626,8 @@ static ExtrusionEntityCollection traverse_extrusions(const PerimeterGenerator& p
     bool &steep_overhang_contour, bool &steep_overhang_hole)
 {
     // Detect steep overhangs
-    bool overhangs_reverse = perimeter_generator.layer_id % 2 == 1 // Only calculate overhang degree on odd layers
+    bool overhangs_reverse = perimeter_generator.config->overhang_reverse
+                             && perimeter_generator.layer_id % 2 == 1 // Only calculate overhang degree on odd layers
                              && perimeter_generator.config->fuzzy_skin == FuzzySkinType::None; // and not fuzzy skin
 
     ExtrusionEntityCollection extrusion_coll;
@@ -696,7 +696,7 @@ static ExtrusionEntityCollection traverse_extrusions(const PerimeterGenerator& p
 
                     BoundingBox extrusion_bboxs = get_extents(be_clipped);
 
-                    if (detect_steep_overhang(pg_extrusion.is_contour, extrusion_bboxs, it.first, be_clipped, perimeter_generator.lower_slices,
+                    if (detect_steep_overhang(perimeter_generator.config, pg_extrusion.is_contour, extrusion_bboxs, it.first, be_clipped, perimeter_generator.lower_slices,
                         steep_overhang_contour, steep_overhang_hole)) {
                         break;
                     }

src/libslic3r/Preset.cpp

@@ -718,7 +718,7 @@ 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",
+    "extra_perimeters_on_overhangs", "ensure_vertical_shell_thickness", "reduce_crossing_wall", "detect_thin_wall", "detect_overhang_wall", "overhang_reverse", "overhang_reverse_threshold",
     "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

@@ -807,6 +807,25 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionBool(false));
 
+    def = this->add("overhang_reverse", coBool);
+    def->label = L("Reverse on odd");
+    def->full_label = L("Overhang reversal");
+    def->category = L("Quality");
+    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_threshold", coFloatOrPercent);
+    def->label = L("Reverse threshold");
+    def->full_label = L("Overhang reversal threshold");
+    def->category = L("Quality");
+    def->tooltip = L("Number of mm the overhang need to be for the reversal to be considered useful. Can be a % of the perimeter width.");
+    def->ratio_over = "line_width";
+    def->min = 0;
+    def->max_literal = 20;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloatOrPercent(50, true));
+
     def = this->add("overhang_speed_classic", coBool);
     def->label = L("Classic mode");
     def->category = L("Speed");

src/libslic3r/PrintConfig.hpp

@@ -828,6 +828,8 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionBool,                 hole_to_polyhole))
     ((ConfigOptionFloatOrPercent,       hole_to_polyhole_threshold))
     ((ConfigOptionBool,                 hole_to_polyhole_twisted))
+    ((ConfigOptionBool,                 overhang_reverse))
+    ((ConfigOptionFloatOrPercent,       overhang_reverse_threshold))
 )
 
 PRINT_CONFIG_CLASS_DEFINE(

src/libslic3r/PrintObject.cpp

@@ -1084,6 +1084,8 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "fuzzy_skin_thickness"
             || opt_key == "fuzzy_skin_point_distance"
             || opt_key == "detect_overhang_wall"
+            || opt_key == "overhang_reverse"
+            || opt_key == "overhang_reverse_threshold"
             //BBS
             || opt_key == "enable_overhang_speed"
             || opt_key == "detect_thin_wall"

src/slic3r/GUI/ConfigManipulation.cpp

@@ -724,6 +724,12 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, co
 
     for (auto el : { "hole_to_polyhole_threshold", "hole_to_polyhole_twisted" })
         toggle_line(el, config->opt_bool("hole_to_polyhole"));
+
+    bool has_detect_overhang_wall = config->opt_bool("detect_overhang_wall");
+    bool has_overhang_reverse     = config->opt_bool("overhang_reverse");
+    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);
 }
 
 void ConfigManipulation::update_print_sla_config(DynamicPrintConfig* config, const bool is_global_config/* = false*/)

src/slic3r/GUI/Tab.cpp

@@ -1910,6 +1910,8 @@ void TabPrint::build()
         optgroup->append_single_option_line("reduce_crossing_wall");
         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_threshold");
 
     page = add_options_page(L("Strength"), "empty");
         optgroup = page->new_optgroup(L("Walls"), L"param_wall");