From a9aaab8337dfcab08f377ba549be26f647d5e5c0 Mon Sep 17 00:00:00 2001
From: AJ Isaacs <ajisaacs27@gmail.com>
Date: Sat, 14 Mar 2026 12:41:03 -0400
Subject: [PATCH] refactor: use ShapeProfile perimeter for boundary and
 intersection

Replace shape-list iteration with ShapeProfile.Perimeter in both
Part.Intersects and PartBoundary, simplifying the logic and ensuring
only the outermost contour is used for collision detection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 OpenNest.Core/Part.cs           | 32 +++++++++++++-------------------
 OpenNest.Engine/PartBoundary.cs | 28 ++++++++++++++++------------
 2 files changed, 29 insertions(+), 31 deletions(-)

diff --git a/OpenNest.Core/Part.cs b/OpenNest.Core/Part.cs
index e5e4adc..56598f4 100644
--- a/OpenNest.Core/Part.cs
+++ b/OpenNest.Core/Part.cs
@@ -149,31 +149,25 @@ namespace OpenNest
             pts = new List<Vector>();
 
             var entities1 = ConvertProgram.ToGeometry(Program)
-                .Where(e => e.Layer != SpecialLayers.Rapid);
+                .Where(e => e.Layer != SpecialLayers.Rapid)
+                .ToList();
             var entities2 = ConvertProgram.ToGeometry(part.Program)
-                .Where(e => e.Layer != SpecialLayers.Rapid);
+                .Where(e => e.Layer != SpecialLayers.Rapid)
+                .ToList();
 
-            var shapes1 = Helper.GetShapes(entities1);
-            var shapes2 = Helper.GetShapes(entities2);
+            if (entities1.Count == 0 || entities2.Count == 0)
+                return false;
 
-            shapes1.ForEach(shape => shape.Offset(Location));
-            shapes2.ForEach(shape => shape.Offset(part.Location));
+            var perimeter1 = new ShapeProfile(entities1).Perimeter;
+            var perimeter2 = new ShapeProfile(entities2).Perimeter;
 
-            for (int i = 0; i < shapes1.Count; i++)
-            {
-                var shape1 = shapes1[i];
+            if (perimeter1 == null || perimeter2 == null)
+                return false;
 
-                for (int j = 0; j < shapes2.Count; j++)
-                {
-                    var shape2 = shapes2[j];
-                    List<Vector> pts2;
+            perimeter1.Offset(Location);
+            perimeter2.Offset(part.Location);
 
-                    if (shape1.Intersects(shape2, out pts2))
-                        pts.AddRange(pts2);
-                }
-            }
-
-            return pts.Count > 0;
+            return perimeter1.Intersects(perimeter2, out pts);
         }
 
         public double Left
diff --git a/OpenNest.Engine/PartBoundary.cs b/OpenNest.Engine/PartBoundary.cs
index 4ab96fc..2545b93 100644
--- a/OpenNest.Engine/PartBoundary.cs
+++ b/OpenNest.Engine/PartBoundary.cs
@@ -23,22 +23,26 @@ namespace OpenNest
 
         public PartBoundary(Part part, double spacing)
         {
-            var entities = ConvertProgram.ToGeometry(part.Program);
-            var shapes = Helper.GetShapes(entities.Where(e => e.Layer != SpecialLayers.Rapid));
+            var entities = ConvertProgram.ToGeometry(part.Program)
+                .Where(e => e.Layer != SpecialLayers.Rapid)
+                .ToList();
+
+            var definedShape = new ShapeProfile(entities);
+            var perimeter = definedShape.Perimeter;
             _polygons = new List<Polygon>();
 
-            foreach (var shape in shapes)
+            if (perimeter != null)
             {
-                var offsetEntity = shape.OffsetEntity(spacing, OffsetSide.Left) as Shape;
+                var offsetEntity = perimeter.OffsetEntity(spacing, OffsetSide.Left) as Shape;
 
-                if (offsetEntity == null)
-                    continue;
-
-                // Circumscribe arcs so polygon vertices are always outside
-                // the true arc — guarantees the boundary never under-estimates.
-                var polygon = offsetEntity.ToPolygonWithTolerance(PolygonTolerance, circumscribe: true);
-                polygon.RemoveSelfIntersections();
-                _polygons.Add(polygon);
+                if (offsetEntity != null)
+                {
+                    // Circumscribe arcs so polygon vertices are always outside
+                    // the true arc — guarantees the boundary never under-estimates.
+                    var polygon = offsetEntity.ToPolygonWithTolerance(PolygonTolerance, circumscribe: true);
+                    polygon.RemoveSelfIntersections();
+                    _polygons.Add(polygon);
+                }
             }
 
             PrecomputeDirectionalEdges(