feat: add PairEvaluator with overlap detection and rotating calipers

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

OpenNest.Engine/BestFit/PairEvaluator.cs

@@ -0,0 +1,122 @@
+using System.Collections.Generic;
+using System.Linq;
+using OpenNest.Converters;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Engine.BestFit
+{
+    public class PairEvaluator
+    {
+        private const double ChordTolerance = 0.01;
+
+        public BestFitResult Evaluate(PairCandidate candidate)
+        {
+            var drawing = candidate.Drawing;
+
+            // Build part1 at origin
+            var part1 = new Part(drawing);
+            var bbox1 = part1.Program.BoundingBox();
+            part1.Offset(-bbox1.Location.X, -bbox1.Location.Y);
+            part1.UpdateBounds();
+
+            // Build part2 with rotation, normalized to origin, then positioned
+            var part2 = new Part(drawing);
+            if (!candidate.Part2Rotation.IsEqualTo(0))
+                part2.Rotate(candidate.Part2Rotation);
+            var bbox2 = part2.Program.BoundingBox();
+            part2.Offset(-bbox2.Location.X, -bbox2.Location.Y);
+            part2.Location = candidate.Part2Offset;
+            part2.UpdateBounds();
+
+            // Check overlap via shape intersection
+            var overlaps = CheckOverlap(part1, part2);
+
+            // Collect all polygon vertices for convex hull / optimal rotation
+            var allPoints = GetPartVertices(part1);
+            allPoints.AddRange(GetPartVertices(part2));
+
+            // Find optimal bounding rectangle via rotating calipers
+            double bestArea, bestWidth, bestHeight, bestRotation;
+
+            if (allPoints.Count >= 3)
+            {
+                var hull = ConvexHull.Compute(allPoints);
+                var result = RotatingCalipers.MinimumBoundingRectangle(hull);
+                bestArea = result.Area;
+                bestWidth = result.Width;
+                bestHeight = result.Height;
+                bestRotation = result.Angle;
+            }
+            else
+            {
+                var combinedBox = ((IEnumerable<IBoundable>)new IBoundable[] { part1, part2 }).GetBoundingBox();
+                bestArea = combinedBox.Area();
+                bestWidth = combinedBox.Width;
+                bestHeight = combinedBox.Height;
+                bestRotation = 0;
+            }
+
+            var trueArea = drawing.Area * 2;
+
+            return new BestFitResult
+            {
+                Candidate = candidate,
+                RotatedArea = bestArea,
+                BoundingWidth = bestWidth,
+                BoundingHeight = bestHeight,
+                OptimalRotation = bestRotation,
+                TrueArea = trueArea,
+                Keep = !overlaps,
+                Reason = overlaps ? "Overlap detected" : "Valid"
+            };
+        }
+
+        private bool CheckOverlap(Part part1, Part part2)
+        {
+            var shapes1 = GetPartShapes(part1);
+            var shapes2 = GetPartShapes(part2);
+
+            for (var i = 0; i < shapes1.Count; i++)
+            {
+                for (var j = 0; j < shapes2.Count; j++)
+                {
+                    List<Vector> pts;
+
+                    if (shapes1[i].Intersects(shapes2[j], out pts))
+                        return true;
+                }
+            }
+
+            return false;
+        }
+
+        private List<Shape> GetPartShapes(Part part)
+        {
+            var entities = ConvertProgram.ToGeometry(part.Program)
+                .Where(e => e.Layer != SpecialLayers.Rapid);
+            var shapes = Helper.GetShapes(entities);
+            shapes.ForEach(s => s.Offset(part.Location));
+            return shapes;
+        }
+
+        private List<Vector> GetPartVertices(Part part)
+        {
+            var entities = ConvertProgram.ToGeometry(part.Program)
+                .Where(e => e.Layer != SpecialLayers.Rapid);
+            var shapes = Helper.GetShapes(entities);
+            var points = new List<Vector>();
+
+            foreach (var shape in shapes)
+            {
+                var polygon = shape.ToPolygonWithTolerance(ChordTolerance);
+                polygon.Offset(part.Location);
+
+                foreach (var vertex in polygon.Vertices)
+                    points.Add(vertex);
+            }
+
+            return points;
+        }
+    }
+}

OpenNest.Engine/OpenNest.Engine.csproj

@@ -40,6 +40,7 @@
     <Compile Include="BestFit\PairCandidate.cs" />
     <Compile Include="BestFit\BestFitResult.cs" />
     <Compile Include="BestFit\IBestFitStrategy.cs" />
+    <Compile Include="BestFit\PairEvaluator.cs" />
     <Compile Include="BestFit\RotationSlideStrategy.cs" />
     <Compile Include="CirclePacking\Bin.cs" />
     <Compile Include="CirclePacking\FillEndEven.cs" />