一个方便绘出贝塞尔曲线的程序，选好点之后就能画出相应的贝塞尔函数，同时可以调整点的位置来调整曲线。-A convenient procedure for drawing Bezier curves, after the selected point will be able to draw the corresponding Bessel function, while the location of the point can be adjusted to adjust the curve.