实现了均匀B样条曲线,准均匀B样条曲线,非均匀B样条曲线绘制

非均匀有理B样条曲线程序，输入若干个（大于四个）坐标点，拟合出NURBS曲线-fitting NURBS curves input points

用户交互输入若干控制点后，自动生成由这些控制点决定的准均匀三次B样条曲线。要求同时显示每段Bezier曲线的控制多边形。-The user interactive input after a certain number of control points, automatically generated is decided by the control points of quasi uniform B spline curve three times. Also show the Bezi