画出了一条3阶贝塞尔曲线，是一条点虚线，使用的是opengl库。-Draw up a third-order Bezier curve is a dotted line, using opengl library.

绘制Bezier与Bspline曲线,以及相应的曲面绘制，最后实现绘制茶壶等高级物件(Bezier&Bspline,take me a lot of time to finish it, you will konw how to Paint Bspline & Bezier with OpenGL)