说明：  计算机图形学的一个绘图程序，可以实现各种图形的绘制，例如雪花、五角星等，还可实现旋转、扩大、缩小图形等功能
(computer graphics of a mapping procedure, can achieve various graphics rendering, such as snowflakes, five-pointed star. but also achieve rotating, expanding and narrowing the graphics functions)