An MDI view class supporting OpenGL.

(一个opengl程序框架，里面有一个三维坐标球，支持鼠标拖拽调整视图)

a function to get various information about the OpenGL implementation which is currently being used (separate information for the OPENGL and GLU libraries).

manages internally the creation of display lists and offers a primitive interface for display lists execution.

defines mouse cursor to be used inside the views.

offers an object oriented encapsulation of quadric objects for drawing of spheres, cylinders and disks.

offers an object oriented encapsulation of glu tessellator routines for translating non simple polygons (concave, self-intersecting and with holes) in groups of simple ones (triangle strips and fans).

presents a simple interface to draw text strings as 2D bitmaps or complete 3D glyphs.