Add test for self intersection

Author: stephomi

src/manifold/src/edge_op.cpp

@@ -222,9 +222,10 @@ void Manifold::Impl::SimplifyTopology() {
                      precision_};
     for_each_n(policy, countAt(0), nbEdges,
                [=] __host__ __device__(int i) { bflagsPtr[i] = se(i); });
-    std::vector<int> visited(halfedge_.size(), -1);
+    std::vector<glm::ivec2> visited(halfedge_.size(), glm::ivec2(-1));
     for (int i = 0; i < nbEdges; ++i) {
       if (bflags[i]) {
+        visited.resize(0);
         RecursiveEdgeSwap(i, visited);
         numFlagged++;
       }
@@ -485,14 +486,17 @@ void Manifold::Impl::CollapseEdge(const int edge) {
 }
 
 void Manifold::Impl::RecursiveEdgeSwap(const int edge,
-                                       std::vector<int>& visited) {
+                                       std::vector<glm::ivec2>& visited) {
   VecDH<TriRef>& triRef = meshRelation_.triRef;
 
   if (edge < 0) return;
   const int pair = halfedge_[edge].pairedHalfedge;
   if (pair < 0) return;
-  if (visited[edge] == pair) return;
-  visited[edge] = pair;
+
+  // avoid infinite recursion
+  for (int i = 0; i < visited.size(); ++i) {
+    if (visited[i] == glm::ivec2(edge, pair)) return;
+  }
 
   const glm::ivec3 tri0edge = TriOf(edge);
   const glm::ivec3 tri1edge = TriOf(pair);
@@ -572,8 +576,10 @@ void Manifold::Impl::RecursiveEdgeSwap(const int edge,
     SwapEdge();
     const glm::vec2 e23 = v[3] - v[2];
     if (glm::dot(e23, e23) < precision_ * precision_) {
+      visited.resize(0);
       CollapseEdge(tri0edge[2]);
     } else {
+      visited.emplace_back(glm::ivec2(edge, pair));
       RecursiveEdgeSwap(tri0edge[0], visited);
       RecursiveEdgeSwap(tri0edge[1], visited);
       RecursiveEdgeSwap(tri1edge[0], visited);
@@ -586,6 +592,7 @@ void Manifold::Impl::RecursiveEdgeSwap(const int edge,
   }
   // Normal path
   SwapEdge();
+  visited.emplace_back(glm::ivec2(edge, pair));
   RecursiveEdgeSwap(halfedge_[tri0edge[1]].pairedHalfedge, visited);
   RecursiveEdgeSwap(halfedge_[tri1edge[0]].pairedHalfedge, visited);
 }

src/manifold/src/impl.h

@@ -121,7 +121,7 @@ struct Manifold::Impl {
   void SimplifyTopology();
   void DedupeEdge(int edge);
   void CollapseEdge(int edge);
-  void RecursiveEdgeSwap(int edge, std::vector<int>& visited);
+  void RecursiveEdgeSwap(int edge, std::vector<glm::ivec2>& visited);
   void RemoveIfFolded(int edge);
   void PairUp(int edge0, int edge1);
   void UpdateVert(int vert, int startEdge, int endEdge);

test/models/self_intersectA.glb

@@ -255,3 +255,16 @@ TEST(Samples, Sponge4) {
 #endif
 }
 #endif
+
+#ifdef MANIFOLD_EXPORT
+TEST(Samples, SelfIntersect) {
+  manifold::PolygonParams().processOverlaps = true;
+  std::string file = __FILE__;
+  std::string dir = file.substr(0, file.rfind('/'));
+  Manifold m1 = ImportMesh(dir + "/models/self_intersectA.glb");
+  Manifold m2 = ImportMesh(dir + "/models/self_intersectB.glb");
+  Manifold res = m1 + m2;
+  res.GetMeshGL();  // test crash
+  manifold::PolygonParams().processOverlaps = false;
+}
+#endif