def METHOD_NAME():
    global vertexNormals
    vertexNormals = []
    _faces = facesFromFacesIndex()
    for vertex in vertices:
        normal = [0,0,0]
        for face in _faces:
            if vertex in face:
                normal = V3.add(normal, calcSurfaceNormals(*face) )
        vertexNormals.append(V3.normalize(normal))