三次Bezier曲线虽然原理跟二次Bezier曲线的类似，但是具体编程时还是有很多地方需要注意，因实际应用中三次Bezier曲线的作用越来越大，所以编了此程序以供参考-cubic Bezier curve Although the Second Principle Bezier curve with a similar, but specific programming when there are still many areas that need attention, according to the actual application of cubic Bezier curves bigger role, so part of this program for reference