HalfEdge.face_vertex_ancestor

HalfEdge.face_vertex_ancestor(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.