图型学的一个演示，包括：坐标系的建立，正平行投影，斜等侧投影，斜二侧投影，长方体的建立，旋转轴的建立，长方体绕轴的旋转。-map-a demonstration of the school, including : the establishment of the coordinate system is parallel to the projection, such as lateral oblique projection, the two lateral oblique projecti

实现一个背景画图，其中用到了双缓冲画图和View画图，画了椭圆和长方体-The realization of a background drawing, which uses a double buffer drawing and View drawing, painting of the elliptic and rectangular parallelepiped