Merge branch 'Degenerate_assertion' into 'master'

Throw assertion in debug when adding topologically degenerate faces

Closes #66

See merge request OpenMesh/OpenMesh!296

src/OpenMesh/Core/Mesh/PolyConnectivity.cc

@@ -304,6 +304,14 @@ PolyConnectivity::add_face(const VertexHandle* _vertex_handles, size_t _vhs_size
 
 SmartFaceHandle PolyConnectivity::add_face(VertexHandle _vh0, VertexHandle _vh1, VertexHandle _vh2, VertexHandle _vh3)
 {
+  // Check if we have been given a degenerate configuration (2 vertices are identical)
+  assert(_vh0!=_vh1);
+  assert(_vh0!=_vh2);
+  assert(_vh1!=_vh2); 
+  assert(_vh0!=_vh3);
+  assert(_vh1!=_vh3);
+  assert(_vh2!=_vh3); 
+  
   VertexHandle vhs[4] = { _vh0, _vh1, _vh2, _vh3 };
   return add_face(vhs, 4);
 }
@@ -312,6 +320,11 @@ SmartFaceHandle PolyConnectivity::add_face(VertexHandle _vh0, VertexHandle _vh1,
 
 SmartFaceHandle PolyConnectivity::add_face(VertexHandle _vh0, VertexHandle _vh1, VertexHandle _vh2)
 {
+  // Check if we have been given a degenerate configuration (2 vertices are identical)
+  assert(_vh0!=_vh1);
+  assert(_vh0!=_vh2);
+  assert(_vh1!=_vh2);
+
   VertexHandle vhs[3] = { _vh0, _vh1, _vh2 };
   return add_face(vhs, 3);
 }

src/Unittests/unittests_convert_meshes.cc

@@ -201,8 +201,12 @@ TEST_F(OpenMeshConvertPolyMeshToTriangle, VertexFaceCheck) {
   EXPECT_EQ(4u, p.n_vertices() ) << "Wrong number of vertices in TriMesh";
 
   Mesh::VertexIter it = mesh_.vertices_begin();
+
+
   //add face to original mesh
-  mesh_.add_face(vhand,(*it),(*++it));
+  Mesh::VertexHandle vhand1 = *it;
+  Mesh::VertexHandle vhand2 = (*++it);
+  mesh_.add_face(vhand,vhand1,vhand2);
 
   EXPECT_EQ(2u, mesh_.n_faces() ) << "Wrong number of faces in PolyMesh";
   EXPECT_EQ(2u, p.n_faces() ) << "Wrong number of faces in TriMesh";