surfacemesh.py 文件源码

def rotate_coord_sys(old_u, old_v, new_norm):
        """Rotate a coordinate system to be perpendicular to the given normal."""
        new_u = old_u
        new_v = old_v
        old_norm = np.cross(old_u, old_v)
        # Project old normal onto new normal
        ndot = np.dot(old_norm, new_norm)
        # If projection is leq to -1, simply reverse
        if ndot <= -1:
            new_u = -new_u
            new_v = -new_v
            return new_u, new_v
        # Otherwise, compute new normal
        perp_old = new_norm - ndot * old_norm
        dperp = (old_norm + new_norm) / (1 + ndot)
        new_u -= dperp * np.dot(new_u, perp_old)
        new_v -= dperp * np.dot(new_v, perp_old)
        return new_u, new_v