drag the control points
definetly not the best way to do this just a little experiment... https://ja.wikipedia.org/wiki/%E7%B7%9A%E5%BD%A2%E8%A3%9C%E9%96%93 https://ja.wikipedia.org/wiki/%E3%83%99%E3%82%B8%E3%82%A7%E6%9B%B2%E7%B7%9A
