三次Bezier曲线法的扫描转换程序：可以通过四个控制点来确定P(t)取不同的t时对应的二维坐标。用三次Bezier曲线绘制的一片花瓣和一根曲线。-Three Bezier curve scan conversion process: the four control points can be determined by P (t) at t different from the corresponding two-dimensional coordinates. Bezier curve w