实现坐标系的变换，把原点定义在显示器的中心点，显示X,Y坐标轴；

2.绘制一个二维图形（可以使用语言库中的画多边形函数）；

3.实现二维图形的平移、比例、对称、选择、错切、复合变换。

-To achieve the coordinate system transformation, the origin define the center of the display shows X, Y axis　2. Draw a two-dimensional graphics (you can use the language library polygon drawing functions)　3. To achieve two-dimensional graphics translation, proportion, symmetry, selection, shear, composite transform.