Run the attached java program.

Press "3" to modify the triMesh's points and faces with the points and faces of a smaller mesh. You should see that MeshView displays a bad mesh. This problem doesn't happen when the triMesh's points and faces are modified with the points and faces of a bigger mesh (press "4").

There is a workaround for this, although non ideal if the triangle mesh is modified frequently. The workaround to this problem is to create a new TriangleMesh and fill it with the desired points and faces (press "1" or "2").