AdaptiveGrid.AddEdge no longer delete edges in case where new edge …

…partially overlaps old edges without intersections.

CHANGELOG.md

@@ -67,6 +67,7 @@
 - `BoundedCurve.ToPolyline` now works correctly for `EllipticalArc` class.
 - `Ray.Intersects(Topography)` and `Ray.Intersects(Mesh)` would sometimes return a different intersection than the closest one.
 - `Ray.Intersects(Topography)` now considers the topography's transform.
+- `AdaptiveGrid.AddEdge` no longer delete edges in case where new edge partially overlaps old edges without intersections.
 
 ### Changed
 

Elements/src/Spatial/AdaptiveGrid/AdaptiveGrid.cs

@@ -936,12 +936,14 @@ private List<Edge> AddCutEdge(ulong startId, ulong endId)
                             AddEdgeOverlappingExisting(edgeV0, edgeV1, startVertex, endVertex, true))
                         {
                             edgesToRemove.Add(edge);
+                            intersectionPoints.Add(oldEdgeLine.End);
                         }
 
                         if (isOldEdgeStartOnNewEdge &&
                             AddEdgeOverlappingExisting(edgeV0, edgeV1, startVertex, endVertex, false))
                         {
                             edgesToRemove.Add(edge);
+                            intersectionPoints.Add(oldEdgeLine.Start);
                         }
                     }
                     // old edge is inside new edge

Elements/test/AdaptiveGridTests.cs

@@ -989,6 +989,41 @@ public void AdaptiveGridAddCutEdge()
             Assert.Equal(new Vector3(6, 4), otherVertex.Point);
         }
 
+        [Fact]
+        public void AdaptiveGridAddCutWithOverlap()
+        {
+            var grid = new AdaptiveGrid();
+            //Create single edges, so cut operation process only overlaps and not intersections.
+            grid.AddEdge(new Vector3(0, 0), new Vector3(0, 10));
+
+            //Start point of new edge is outside, end is inside.
+            var v0 = grid.AddVertex(new Vector3(0, -5));
+            var v1 = grid.AddVertex(new Vector3(0, 3));
+            var edges = grid.AddEdge(v0.Id, v1.Id);
+            Assert.Equal(2, edges.Count);
+            Assert.Single(v0.Edges);
+            Assert.Equal(2, v1.Edges.Count);
+            var middle = edges.First().OtherVertexId(v0.Id);
+            var middleVertex = grid.GetVertex(middle);
+            Assert.Equal(new Vector3(0, 0), middleVertex.Point);
+            Assert.Equal(2, middleVertex.Edges.Count);
+
+            //End point of new edge is outside, start is inside.
+            v0 = grid.AddVertex(new Vector3(0, 7));
+            v1 = grid.AddVertex(new Vector3(0, 15));
+            edges = grid.AddEdge(v0.Id, v1.Id);
+            Assert.Equal(2, edges.Count);
+            Assert.Equal(2, v0.Edges.Count);
+            Assert.Single(v1.Edges);
+            middle = edges.Last().OtherVertexId(v1.Id);
+            middleVertex = grid.GetVertex(middle);
+            Assert.Equal(new Vector3(0, 10), middleVertex.Point);
+            Assert.Equal(2, middleVertex.Edges.Count);
+
+            // Result should be strip of 6 vertices.
+            Assert.Equal(6, grid.GetVertices().Count);
+        }
+
         [Fact]
         public void AdaptiveGridAddVertexWithAngle()
         {