Perfrom seam placing on geometry only for SeamAligned, otherwise use extrusions

src/libslic3r/GCode/SeamGeometry.cpp

@@ -218,7 +218,7 @@ BoundedPolygons project_to_geometry(const Geometry::Extrusions &external_perimet
                 Polygons expanded_extrusion{expand(external_perimeter.polygon, external_perimeter.width / 2.0)};
                 if (!expanded_extrusion.empty()) {
                     return BoundedPolygon{
-                        expanded_extrusion.front(), expanded_extrusion.front().bounding_box(), external_perimeter.polygon.is_clockwise()
+                        expanded_extrusion.front(), expanded_extrusion.front().bounding_box(), external_perimeter.polygon.is_clockwise(), 0.0
                     };
                 }
             }
@@ -227,7 +227,7 @@ BoundedPolygons project_to_geometry(const Geometry::Extrusions &external_perimet
             const Polygon &adjacent_boundary{
                 !is_hole ? external_perimeter.island_boundary.contour :
                            external_perimeter.island_boundary.holes[choosen_index - 1]};
-            return BoundedPolygon{adjacent_boundary, external_perimeter.island_boundary_bounding_boxes[choosen_index], is_hole};
+            return BoundedPolygon{adjacent_boundary, external_perimeter.island_boundary_bounding_boxes[choosen_index], is_hole, 0.0};
         }
     );
     return result;
@@ -243,6 +243,27 @@ std::vector<BoundedPolygons> project_to_geometry(const std::vector<Geometry::Ext
     return result;
 }
 
+std::vector<BoundedPolygons> convert_to_geometry(const std::vector<Geometry::Extrusions> &extrusions) {
+    std::vector<BoundedPolygons> result;
+    result.reserve(extrusions.size());
+
+    for (const Geometry::Extrusions &layer : extrusions) {
+        result.emplace_back();
+
+        using std::transform, std::back_inserter;
+        transform(
+            layer.begin(), layer.end(), back_inserter(result.back()),
+            [&](const Geometry::Extrusion &extrusion) {
+                return BoundedPolygon{
+                    extrusion.polygon, extrusion.bounding_box, extrusion.polygon.is_clockwise(), extrusion.width / 2.0
+                };
+            }
+        );
+    }
+
+    return result;
+}
+
 std::vector<Vec2d> oversample_edge(const Vec2d &from, const Vec2d &to, const double max_distance) {
     const double total_distance{(from - to).norm()};
     const auto points_count{static_cast<std::size_t>(std::ceil(total_distance / max_distance)) + 1};

src/libslic3r/GCode/SeamGeometry.hpp

@@ -61,12 +61,14 @@ struct BoundedPolygon {
     Polygon polygon;
     BoundingBox bounding_box;
     bool is_hole{false};
+    double offset_inside{};
 };
 
 using BoundedPolygons = std::vector<BoundedPolygon>;
 
 BoundedPolygons project_to_geometry(const Geometry::Extrusions &external_perimeters, const double max_bb_distance);
 std::vector<BoundedPolygons> project_to_geometry(const std::vector<Geometry::Extrusions> &extrusions, const double max_bb_distance);
+std::vector<BoundedPolygons> convert_to_geometry(const std::vector<Geometry::Extrusions> &extrusions);
 
 Vec2d get_polygon_normal(
     const std::vector<Vec2d> &points, const std::size_t index, const double min_arm_length

src/libslic3r/GCode/SeamPerimeters.cpp

@@ -326,7 +326,8 @@ Perimeter Perimeter::create(
     const Polygon &polygon,
     const ModelInfo::Painting &painting,
     const LayerInfo &layer_info,
-    const PerimeterParams &params
+    const PerimeterParams &params,
+    const double offset_inside
 ) {
     if (polygon.size() < 3) {
         return Perimeter::create_degenerate(
@@ -353,10 +354,17 @@ Perimeter Perimeter::create(
         Impl::oversample_painted(points, is_painted, layer_info.slice_z, params.oversampling_max_distance)};
 
     std::vector<PointType> point_types{
-        Impl::get_point_types(perimeter_points, painting, layer_info.slice_z, params.painting_radius)};
+        Impl::get_point_types(perimeter_points, painting, layer_info.slice_z, offset_inside > 0 ? offset_inside * 2 : params.painting_radius)};
 
-    std::tie(perimeter_points, point_types) =
-        Impl::remove_redundant_points(perimeter_points, point_types, params.simplification_epsilon);
+    // Geometry converted from extrusions has non zero offset_inside.
+    // Do not remomve redundant points for extrusions, becouse the redundant
+    // points can be on overhangs.
+    if (offset_inside < std::numeric_limits<double>::epsilon()) {
+        // The following is optimization with significant impact. If in doubt, run
+        // the "Seam benchmarks" test case in fff_print_tests.
+        std::tie(perimeter_points, point_types) =
+            Impl::remove_redundant_points(perimeter_points, point_types, params.simplification_epsilon);
+    }
 
     const std::vector<double> embeddings{
         Geometry::get_embedding_distances(perimeter_points, layer_info.distancer)};
@@ -411,7 +419,7 @@ LayerPerimeters create_perimeters(
             const Geometry::BoundedPolygon &bounded_polygon{layer[polygon_index]};
             const LayerInfo &layer_info{layer_infos[layer_index]};
             result[layer_index][polygon_index] = BoundedPerimeter{
-                Perimeter::create(bounded_polygon.polygon, painting, layer_info, params),
+                Perimeter::create(bounded_polygon.polygon, painting, layer_info, params, bounded_polygon.offset_inside),
                 bounded_polygon.bounding_box};
         }
     );

src/libslic3r/GCode/SeamPerimeters.hpp

@@ -151,7 +151,8 @@ struct Perimeter
         const Polygon &polygon,
         const ModelInfo::Painting &painting,
         const LayerInfo &layer_info,
-        const PerimeterParams &params
+        const PerimeterParams &params,
+        const double offset_inside
     );
 
     static Perimeter create_degenerate(

src/libslic3r/GCode/SeamPlacer.cpp

@@ -38,7 +38,11 @@ ObjectLayerPerimeters get_perimeters(
         const Perimeters::LayerInfos layer_infos{Perimeters::get_layer_infos(
             print_object->layers(), params.perimeter.elephant_foot_compensation
         )};
-        const std::vector<Geometry::BoundedPolygons> projected{Geometry::project_to_geometry(extrusions, params.max_distance)};
+        const std::vector<Geometry::BoundedPolygons> projected{
+            print_object->config().seam_position == spAligned ?
+            Geometry::project_to_geometry(extrusions, params.max_distance) :
+            Geometry::convert_to_geometry(extrusions)
+        };
         Perimeters::LayerPerimeters perimeters{Perimeters::create_perimeters(projected, layer_infos, painting, params.perimeter)};
 
         throw_if_canceled();