HalfEdge.face_vertex_before
- HalfEdge.face_vertex_before(fkey, key, n=1)[source]
Return the n-th vertex before the specified vertex in a specific face.
- Parameters:
- fkeyint
Identifier of the face.
- keyint
The identifier of the vertex.
- nint, optional
The index of the vertex ancestor. Default is 1, meaning the previous vertex.
- Returns:
- int
The identifier of the vertex before the given vertex in the face cycle.
- Raises:
- ValueError
If the vertex is not part of the face.