Flips the front and the back of parts of the surface as required to create a surface that is oriented. Refer to
isOriented()for the specification of what it means to be an oriented surface. If the surface is improperly noded or non-orientable, the behaviour of this function is undefined. All measures are changed as needed, including the vertex normal measures. Note: The vertex normals are not flipped (scaled by -1).
- Return type