1.绘制三维四边形网格曲面。

2.调整网格曲面显示状态：填充或不填充。

3.改变窗口背景颜色。

4.左键旋转图形，右键缩放图形。-1. Draw three-dimensional quadrilateral mesh surface.

2. Adjustment of the grid surface display status: fill or not fill.

3. To change the window background color.

4. Left rotating graphics, right zoom.