From e84f400fad090b130b9a6107317ad4ee2c503683 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20=C5=A0ach?= <martin.sachin@gmail.com>
Date: Mon, 24 Feb 2025 15:50:39 +0100
Subject: [PATCH] SPE-2701: Disable scarf seam on thick bridges (#14190)

---
 src/libslic3r/GCode/SeamPlacer.cpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/libslic3r/GCode/SeamPlacer.cpp b/src/libslic3r/GCode/SeamPlacer.cpp
index ab89399901..b3a16c8500 100644
--- a/src/libslic3r/GCode/SeamPlacer.cpp
+++ b/src/libslic3r/GCode/SeamPlacer.cpp
@@ -271,7 +271,8 @@ boost::variant<Point, Scarf::Scarf> finalize_seam_position(
     SeamChoice seam_choice,
     const Perimeters::Perimeter &perimeter,
     const bool staggered_inner_seams,
-    const bool flipped
+    const bool flipped,
+    const bool thick_bridges
 ) {
     using Perimeters::offset_along_perimeter;
     using Perimeters::PointOnPerimeter;
@@ -351,6 +352,15 @@ boost::variant<Point, Scarf::Scarf> finalize_seam_position(
         place_scarf_seam = false;
     }
 
+    const bool is_overhang{
+        perimeter.point_classifications[seam_choice.previous_index] == Perimeters::PointClassification::overhang
+        || perimeter.point_classifications[seam_choice.next_index] == Perimeters::PointClassification::overhang
+    };
+
+    if (thick_bridges && is_overhang) {
+        place_scarf_seam = false;
+    }
+
     if (place_scarf_seam) {
         Scarf::Scarf scarf{};
         scarf.entire_loop = region->config().scarf_seam_entire_loop;
@@ -532,6 +542,8 @@ boost::variant<Point, Scarf::Scarf> Placer::place_seam(
     assert(layer->id() >= po->slicing_parameters().raft_layers());
     const size_t layer_index = layer->id() - po->slicing_parameters().raft_layers();
 
+    const bool thick_bridges{po->config().thick_bridges.value};
+
     if (po->config().seam_position.value == spNearest) {
         const std::vector<Perimeters::BoundedPerimeter> &perimeters{
             this->perimeters_per_layer.at(po)[layer_index]};
@@ -539,7 +551,7 @@ boost::variant<Point, Scarf::Scarf> Placer::place_seam(
             place_seam_near(perimeters, loop, last_pos, this->params.max_nearest_detour);
         return finalize_seam_position(
             loop, region, seam_choice, perimeters[perimeter_index].perimeter,
-            this->params.staggered_inner_seams, flipped
+            this->params.staggered_inner_seams, flipped, thick_bridges
         );
     } else {
         const std::vector<SeamPerimeterChoice> &seams_on_perimeters{this->seams_per_object.at(po)[layer_index]};
@@ -557,7 +569,7 @@ boost::variant<Point, Scarf::Scarf> Placer::place_seam(
                                                                seams_on_perimeters[0]};
                 return finalize_seam_position(
                     loop, region, seam_perimeter_choice.choice, seam_perimeter_choice.perimeter,
-                    this->params.staggered_inner_seams, flipped
+                    this->params.staggered_inner_seams, flipped, thick_bridges
                 );
             }
         }
@@ -566,7 +578,7 @@ boost::variant<Point, Scarf::Scarf> Placer::place_seam(
             choose_closest_seam(seams_on_perimeters, Geometry::to_polygon(loop))};
         return finalize_seam_position(
             loop, region, seam_perimeter_choice.choice, seam_perimeter_choice.perimeter,
-            this->params.staggered_inner_seams, flipped
+            this->params.staggered_inner_seams, flipped, thick_bridges
         );
     }
 }