把特定格式的3D模型显示出来，并且能用键盘和鼠标控制。3D文件已包含在压缩包里（abc.obj。-The specific format of 3D model is displayed, and can use the keyboard and mouse control. 3D document has been included in the compression bag (abc.obj.

实现L系统树模型，可通过参数控制，树的生长。-L-system