def _normalize_vectors(rr):
 size = np.sqrt(np.sum((rr * rr), axis=1))
 size[(size == 0)] = 1.0
 rr /= size[:, np.newaxis]

def _normalize_vectors ( rr ) : size = np . sqrt ( np . sum ( ( rr * rr ) , axis = 1 ) ) size [ ( size == 0 ) ] = 1.0 rr /= size [ : , np . newaxis ]
normalize surface vertices .