def get_bbox(self, points=None):
        """
        Get bounding box of this object.

        Returns
        -------
        (p1, p2, p3, p4): a 4-tuple of the points in data coordinates,
        beginning with the lower-left and proceeding counter-clockwise.
        """
        if points is None:
            x1, y1, x2, y2 = self.get_llur()
            return ((x1, y1), (x1, y2), (x2, y2), (x2, y1))
        else:
            return trcalc.strip_z(trcalc.get_bounds(points))