From 024070a4ade97c061ec87c2c5c7d6ac65c0435bc Mon Sep 17 00:00:00 2001
From: katehryhorenko <kate@hypar.io>
Date: Mon, 23 Oct 2023 20:49:12 -0300
Subject: [PATCH] Fixed Intersection method;

---
 Elements/src/GeometricElement.cs              | 68 +++++++++----------
 .../Representations/SolidRepresentation.cs    |  6 +-
 2 files changed, 36 insertions(+), 38 deletions(-)

diff --git a/Elements/src/GeometricElement.cs b/Elements/src/GeometricElement.cs
index 173b3b7db..95f81e3dc 100644
--- a/Elements/src/GeometricElement.cs
+++ b/Elements/src/GeometricElement.cs
@@ -213,7 +213,6 @@ public bool Intersects(Plane plane,
             var graphVertices = new List<Vector3>();
             var graphEdges = new List<List<(int from, int to, int? tag)>>();
 
-            var intersectionPoints = new List<Vector3>();
             var beyondPolygonsList = new List<Polygon>();
 
             if (Representation != null && _csg != null)
@@ -252,7 +251,7 @@ public bool Intersects(Plane plane,
 
                     var d = csgNormal.Cross(plane.Normal).Unitized();
                     edgeResults.Sort(new DirectionComparer(d));
-                    intersectionPoints.AddRange(edgeResults);
+                    AddToGraph(edgeResults, graphVertices, graphEdges);
                 }
             }
 
@@ -268,43 +267,15 @@ public bool Intersects(Plane plane,
 
                     if (instance.Representation is SolidRepresentation solidRepresentation)
                     {
-                        intersectionPoints.AddRange(solidRepresentation.CalculateIntersectionPoints(this, plane,
-                            out var beyondPolygonsLocal));
-                        beyondPolygonsList.AddRange(beyondPolygonsLocal);
+                        foreach (var intersection in solidRepresentation.CalculateIntersectionPoints(this, plane,
+                            out var beyondPolygonsLocal))
+                        {
+                            AddToGraph(intersection, graphVertices, graphEdges);
+                        }
                     }
                 }
             }
 
-            if (!intersectionPoints.Any())
-            {
-                return false;
-            }
-
-            // Draw segments through the results and add to the 
-            // half edge graph.
-            for (var j = 0; j < intersectionPoints.Count - 1; j += 2)
-            {
-                // Don't create zero-length edges.
-                if (intersectionPoints[j].IsAlmostEqualTo(intersectionPoints[j + 1]))
-                {
-                    continue;
-                }
-
-                var a = Solid.FindOrCreateGraphVertex(intersectionPoints[j], graphVertices, graphEdges);
-                var b = Solid.FindOrCreateGraphVertex(intersectionPoints[j + 1], graphVertices, graphEdges);
-                var e1 = (a, b, 0);
-                var e2 = (b, a, 0);
-                if (graphEdges[a].Contains(e1) || graphEdges[b].Contains(e2))
-                {
-                    continue;
-                }
-                else
-                {
-                    graphEdges[a].Add(e1);
-                }
-            }
-            // }
-
             var heg = new HalfEdgeGraph2d()
             {
                 Vertices = graphVertices,
@@ -364,6 +335,33 @@ public bool Intersects(Plane plane,
             }
         }
 
+        private static void AddToGraph(List<Vector3> intersectionPoints, List<Vector3> graphVertices, List<List<(int from, int to, int? tag)>> graphEdges)
+        {
+            // Draw segments through the results and add to the
+            // half edge graph.
+            for (var j = 0; j < intersectionPoints.Count - 1; j += 2)
+            {
+                // Don't create zero-length edges.
+                if (intersectionPoints[j].IsAlmostEqualTo(intersectionPoints[j + 1]))
+                {
+                    continue;
+                }
+
+                var a = Solid.FindOrCreateGraphVertex(intersectionPoints[j], graphVertices, graphEdges);
+                var b = Solid.FindOrCreateGraphVertex(intersectionPoints[j + 1], graphVertices, graphEdges);
+                var e1 = (a, b, 0);
+                var e2 = (b, a, 0);
+                if (graphEdges[a].Contains(e1) || graphEdges[b].Contains(e2))
+                {
+                    continue;
+                }
+                else
+                {
+                    graphEdges[a].Add(e1);
+                }
+            }
+        }
+
         /// <summary>
         /// Get the computed csg solid.
         /// The csg is centered on the origin by default.
diff --git a/Elements/src/Representations/SolidRepresentation.cs b/Elements/src/Representations/SolidRepresentation.cs
index 6abab334b..5832a154a 100644
--- a/Elements/src/Representations/SolidRepresentation.cs
+++ b/Elements/src/Representations/SolidRepresentation.cs
@@ -147,9 +147,9 @@ public BBox3 ComputeBounds(GeometricElement element)
         /// <param name="plane">The intersecting plane.</param>
         /// <param name="beyondPolygons">The output collection of the polygons beyond the input plane.</param>
         /// <returns>Returns the collection of intersection points.</returns>
-        public List<Vector3> CalculateIntersectionPoints(GeometricElement element, Plane plane, out List<Polygon> beyondPolygons)
+        public List<List<Vector3>> CalculateIntersectionPoints(GeometricElement element, Plane plane, out List<Polygon> beyondPolygons)
         {
-            var intersectionPoints = new List<Vector3>();
+            var intersectionPoints = new List<List<Vector3>>();
             beyondPolygons = new List<Polygon>();
 
             var csg = SolidOperationUtils.GetFinalCsgFromSolids(SolidOperations, element, true);
@@ -186,7 +186,7 @@ public List<Vector3> CalculateIntersectionPoints(GeometricElement element, Plane
 
                 var d = csgNormal.Cross(plane.Normal).Unitized();
                 edgeResults.Sort(new DirectionComparer(d));
-                intersectionPoints.AddRange(edgeResults);
+                intersectionPoints.Add(edgeResults);
             }
 
             return intersectionPoints;