Add support for Inner>Outer>Inner perimeter order

src/libslic3r/Arachne/PerimeterOrder.cpp

@@ -215,7 +215,10 @@ static std::vector<size_t> order_of_grouped_perimeter_extrusions_to_minimize_dis
     return grouped_extrusions_order;
 }
 
-static PerimeterExtrusions extract_ordered_perimeter_extrusions(const PerimeterExtrusions &sorted_perimeter_extrusions, const bool external_perimeters_first) {
+static PerimeterExtrusions extract_ordered_perimeter_extrusions(
+    const PerimeterExtrusions &sorted_perimeter_extrusions,
+    const PerimeterGenerator::Parameters &params
+) {
     // Extrusions are ordered inside each group.
     std::vector<GroupedPerimeterExtrusions> grouped_extrusions;
 
@@ -260,8 +263,28 @@ static PerimeterExtrusions extract_ordered_perimeter_extrusions(const PerimeterE
             }
         }
 
-        if (!external_perimeters_first)
-            std::reverse(grouped_extrusions.back().extrusions.begin(), grouped_extrusions.back().extrusions.end());
+        // Make the order inner->outer by default.
+        // This causes a potential double reverse, but this way the conditions are consistent with
+        // the classic perimeter generator
+        std::reverse(
+            grouped_extrusions.back().extrusions.begin(), grouped_extrusions.back().extrusions.end()
+        );
+        // if brim will be printed, reverse the order of perimeters so that
+        // we continue inwards after having finished the brim
+        const bool first_layer_with_brim = params.layer_id == 0 &&
+            params.object_config.brim_width.value > 0 &&
+            params.object_config.brim_separation == 0 && params.object_config.brim_type != btNoBrim;
+        if (params.config.perimeters_order == PerimetersOrder::OuterInner || first_layer_with_brim)
+            std::reverse(
+                grouped_extrusions.back().extrusions.begin(),
+                grouped_extrusions.back().extrusions.end()
+            );
+        if (params.config.perimeters_order == PerimetersOrder::InnerOuterInner &&
+            !first_layer_with_brim && grouped_extrusions.back().extrusions.size() > 1)
+            std::swap(
+                *std::prev(grouped_extrusions.back().extrusions.end(), 1),
+                *std::prev(grouped_extrusions.back().extrusions.end(), 2)
+            );
     }
 
     const std::vector<size_t> grouped_extrusion_order = order_of_grouped_perimeter_extrusions_to_minimize_distances(grouped_extrusions, Point::Zero());
@@ -277,11 +300,13 @@ static PerimeterExtrusions extract_ordered_perimeter_extrusions(const PerimeterE
 
 // FIXME: From the point of better patch planning, it should be better to do ordering when we have generated all extrusions (for now, when G-Code is exported).
 // FIXME: It would be better to extract the adjacency graph of extrusions from the SkeletalTrapezoidation graph.
-PerimeterExtrusions ordered_perimeter_extrusions(const Perimeters &perimeters, const bool external_perimeters_first) {
+PerimeterExtrusions ordered_perimeter_extrusions(
+    const Perimeters &perimeters, const PerimeterGenerator::Parameters &params
+) {
     PerimeterExtrusions sorted_perimeter_extrusions = get_sorted_perimeter_extrusions_by_area(perimeters);
     construct_perimeter_extrusions_adjacency_graph(sorted_perimeter_extrusions);
     assign_nearest_external_perimeter(sorted_perimeter_extrusions);
-    return extract_ordered_perimeter_extrusions(sorted_perimeter_extrusions, external_perimeters_first);
+    return extract_ordered_perimeter_extrusions(sorted_perimeter_extrusions, params);
 }
 
 } // namespace Slic3r::Arachne::PerimeterOrder

src/libslic3r/Arachne/PerimeterOrder.hpp

@@ -6,6 +6,7 @@
 #include <vector>
 #include <cstddef>
 
+#include "libslic3r/PerimeterGenerator.hpp"
 #include "libslic3r/Arachne/utils/ExtrusionLine.hpp"
 #include "libslic3r/BoundingBox.hpp"
 #include "libslic3r/Polygon.hpp"
@@ -44,7 +45,9 @@ struct PerimeterExtrusion
 
 using PerimeterExtrusions = std::vector<PerimeterExtrusion>;
 
-PerimeterExtrusions ordered_perimeter_extrusions(const Perimeters &perimeters, bool external_perimeters_first);
+PerimeterExtrusions ordered_perimeter_extrusions(
+    const Perimeters &perimeters, const PerimeterGenerator::Parameters &params
+);
 
 } // namespace Slic3r::Arachne::PerimeterOrder
 

src/libslic3r/GCode/SeamPlacer.cpp

@@ -397,7 +397,7 @@ boost::variant<Point, Scarf::Scarf> finalize_seam_position(
                 *outter_scarf_start_point
             };
 
-            if (region->config().external_perimeters_first.value) {
+            if (region->config().perimeters_order.value != PerimetersOrder::InnerOuter) {
                 const auto external_first_offset_direction{
                     offset_direction == Geometry::Direction1D::forward ?
                     Geometry::Direction1D::backward :

src/libslic3r/Layer.cpp

@@ -658,7 +658,7 @@ inline bool has_compatible_layer_regions(const PrintRegionConfig &config, const
            config.overhangs                                             == other_config.overhangs &&
            config.opt_serialize("perimeter_extrusion_width")     == other_config.opt_serialize("perimeter_extrusion_width") &&
            config.thin_walls                                            == other_config.thin_walls &&
-           config.external_perimeters_first                             == other_config.external_perimeters_first &&
+           config.perimeters_order                                      == other_config.perimeters_order &&
            config.infill_overlap                                        == other_config.infill_overlap &&
            has_compatible_dynamic_overhang_speed(config, other_config);
 }

src/libslic3r/PerimeterGenerator.cpp

@@ -1121,7 +1121,8 @@ void PerimeterGenerator::process_arachne(
         return true;
     }());
 
-    Arachne::PerimeterOrder::PerimeterExtrusions ordered_extrusions = Arachne::PerimeterOrder::ordered_perimeter_extrusions(perimeters, params.config.external_perimeters_first);
+    Arachne::PerimeterOrder::PerimeterExtrusions ordered_extrusions =
+        Arachne::PerimeterOrder::ordered_perimeter_extrusions(perimeters, params);
 
     if (ExtrusionEntityCollection extrusion_coll = traverse_extrusions(params, lower_slices_polygons_cache, ordered_extrusions); !extrusion_coll.empty())
         out_loops.append(extrusion_coll);
@@ -1452,9 +1453,15 @@ void PerimeterGenerator::process_classic(
         // if brim will be printed, reverse the order of perimeters so that
         // we continue inwards after having finished the brim
         // TODO: add test for perimeter order
-        if (params.config.external_perimeters_first || 
-            (params.layer_id == 0 && params.object_config.brim_width.value > 0))
+        const bool first_layer_with_brim = params.layer_id == 0 &&
+            params.object_config.brim_width.value > 0 &&
+            params.object_config.brim_separation == 0 && params.object_config.brim_type != btNoBrim;
+        if (params.config.perimeters_order == PerimetersOrder::OuterInner || first_layer_with_brim)
             entities.reverse();
+        if (params.config.perimeters_order == PerimetersOrder::InnerOuterInner &&
+            !first_layer_with_brim && entities.size() > 1)
+            std::swap(*std::prev(entities.end(), 1), *std::prev(entities.end(), 2));
+
         // append perimeters for this slice as a collection
         if (! entities.empty())
             out_loops.append(entities);

src/libslic3r/Preset.cpp

@@ -474,7 +474,7 @@ static std::vector<std::string> s_Preset_print_options {
     "ensure_vertical_shell_thickness", "extra_perimeters", "extra_perimeters_on_overhangs",
     "avoid_crossing_curled_overhangs", "avoid_crossing_perimeters", "thin_walls", "overhangs",
     "seam_position", "staggered_inner_seams", "seam_gap_distance",
-    "external_perimeters_first", "fill_density", "fill_pattern", "top_fill_pattern", "bottom_fill_pattern",
+    "perimeters_order", "fill_density", "fill_pattern", "top_fill_pattern", "bottom_fill_pattern",
     "scarf_seam_placement", "scarf_seam_only_on_smooth", "scarf_seam_start_height", "scarf_seam_entire_loop", "scarf_seam_length", "scarf_seam_max_segment_length", "scarf_seam_on_inner_perimeters",
     "infill_every_layers", /*"infill_only_where_needed",*/ "solid_infill_every_layers", "fill_angle", "bridge_angle",
     "solid_infill_below_area", "only_retract_when_crossing_perimeters", "infill_first",

src/libslic3r/PrintConfig.cpp

@@ -267,6 +267,13 @@ static const t_config_enum_values s_keys_map_ForwardCompatibilitySubstitutionRul
 };
 CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(ForwardCompatibilitySubstitutionRule)
 
+static t_config_enum_values s_keys_map_PerimetersOrder {
+    {"inner_outer", int(PerimetersOrder::InnerOuter)},
+    {"outer_inner", int(PerimetersOrder::OuterInner)},
+    {"inner_outer_inner", int(PerimetersOrder::InnerOuterInner)}
+};
+CONFIG_OPTION_ENUM_DEFINE_STATIC_MAPS(PerimetersOrder)
+
 static t_config_enum_values s_keys_map_PerimeterGeneratorType {
     { "classic", int(PerimeterGeneratorType::Classic) },
     { "arachne", int(PerimeterGeneratorType::Arachne) }
@@ -1157,13 +1164,20 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionFloatOrPercent(50, true));
 
-    def = this->add("external_perimeters_first", coBool);
-    def->label = L("External perimeters first");
+    def = this->add("perimeters_order", coEnum);
+    def->label = L("Perimeters order");
     def->category = L("Layers and Perimeters");
-    def->tooltip = L("Print contour perimeters from the outermost one to the innermost one "
-                   "instead of the default inverse order.");
+    def->tooltip = L(
+        "Determines printing order of the contour perimeters. If the number of perimeters is less "
+        "than three, the Inner>Outer>Inner option behaves like Outer>Inner"
+    );
+    def->set_enum<PerimetersOrder>(
+        {{"inner_outer", L("Inner>Outer")},
+         {"outer_inner", L("Outer>Inner")},
+         {"inner_outer_inner", L("Inner>Outer>Inner")}}
+    );
     def->mode = comExpert;
-    def->set_default_value(new ConfigOptionBool(false));
+    def->set_default_value(new ConfigOptionEnum<PerimetersOrder>(PerimetersOrder::InnerOuter));
 
     def = this->add("extra_perimeters", coBool);
     def->label = L("Extra perimeters if needed");
@@ -5363,6 +5377,13 @@ void PrintConfigDef::handle_legacy(t_config_option_key &opt_key, std::string &va
             // Values other than 0/1 are replaced with "partial" for handling values from different slicers.
             value = "partial";
         }
+    } else if (opt_key == "external_perimeters_first") {
+        opt_key = "perimeters_order";
+        if (value == "0") {
+            value = "inner_outer";
+        } else {
+            value = "outer_inner";
+        }
     }
 
     // In PrusaSlicer 2.3.0-alpha0 the "monotonous" infill was introduced, which was later renamed to "monotonic".

src/libslic3r/PrintConfig.hpp

@@ -180,6 +180,13 @@ enum class LabelObjectsStyle {
     Disabled, Octoprint, Firmware
 };
 
+enum class PerimetersOrder
+{
+    InnerOuter,
+    OuterInner,
+    InnerOuterInner
+};
+
 enum class PerimeterGeneratorType
 {
     // Classic perimeter generator using Clipper offsets with constant extrusion width.
@@ -754,7 +761,7 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloatOrPercent,       overhang_speed_1))
     ((ConfigOptionFloatOrPercent,       overhang_speed_2))
     ((ConfigOptionFloatOrPercent,       overhang_speed_3))
-    ((ConfigOptionBool,                 external_perimeters_first))
+    ((ConfigOptionEnum<PerimetersOrder>, perimeters_order))
     ((ConfigOptionBool,                 extra_perimeters))
     ((ConfigOptionBool,                 extra_perimeters_on_overhangs))
     ((ConfigOptionFloat,                fill_angle))

src/libslic3r/PrintObject.cpp

@@ -720,6 +720,8 @@ bool PrintObject::invalidate_state_by_config_options(
         if (   opt_key == "brim_width"
             || opt_key == "brim_separation"
             || opt_key == "brim_type") {
+            // Brim can affect the first layer perimeters order so they have to be invalidated
+            steps.emplace_back(posPerimeters);
             steps.emplace_back(posSupportSpotsSearch);
             // Brim is printed below supports, support invalidates brim and skirt.
             steps.emplace_back(posSupportMaterial);
@@ -730,7 +732,7 @@ bool PrintObject::invalidate_state_by_config_options(
             || opt_key == "first_layer_extrusion_width"
             || opt_key == "perimeter_extrusion_width"
             || opt_key == "infill_overlap"
-            || opt_key == "external_perimeters_first"
+            || opt_key == "perimeters_order"
             || opt_key == "arc_fitting"
             || opt_key == "top_one_perimeter_type"
             || opt_key == "only_one_perimeter_first_layer") {

src/slic3r/GUI/ConfigManipulation.cpp

@@ -284,7 +284,7 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig* config)
 {
     bool have_perimeters = config->opt_int("perimeters") > 0;
     for (auto el : { "extra_perimeters","extra_perimeters_on_overhangs", "thin_walls", "overhangs",
-                    "seam_position","staggered_inner_seams", "external_perimeters_first", "external_perimeter_extrusion_width",
+                    "seam_position","staggered_inner_seams", "perimeters_order", "external_perimeter_extrusion_width",
                     "perimeter_speed", "small_perimeter_speed", "external_perimeter_speed", "enable_dynamic_overhang_speeds"})
         toggle_field(el, have_perimeters);
 

src/slic3r/GUI/Tab.cpp

@@ -1488,7 +1488,7 @@ void TabPrint::build()
         optgroup->append_single_option_line("scarf_seam_max_segment_length", scarf_seam_path + "max-scarf-joint-segment-length");
         optgroup->append_single_option_line("scarf_seam_on_inner_perimeters", scarf_seam_path + "scarf-joint-on-inner-perimeters");
 
-        optgroup->append_single_option_line("external_perimeters_first", category_path + "external-perimeters-first");
+        optgroup->append_single_option_line("perimeters_order", category_path + "perimeters-order");
         optgroup->append_single_option_line("gap_fill_enabled", category_path + "fill-gaps");
         optgroup->append_single_option_line("perimeter_generator");