io_export_paper_model.py 文件源码

def z_up_matrix(n):
    """Get a rotation matrix that aligns given vector upwards."""
    b = n.xy.length
    l = n.length
    if b > 0:
        return M.Matrix((
            (n.x*n.z/(b*l), n.y*n.z/(b*l), -b/l),
            (-n.y/b, n.x/b, 0),
            (0, 0, 0)
        ))
    else:
        # no need for rotation
        return M.Matrix((
            (1, 0, 0),
            (0, (-1 if n.z < 0 else 1), 0),
            (0, 0, 0)
        ))