Mac OS X layer structure:
1. User interface;
2. Application framework—including Cocoa,carbon.classic
3. Picture and media—including Quartz.OpenGL.Quicktime.
4. Basics—BSD(a variation of UNIX)

OpenGL
1. What’s OpenGL?
OpenGL is a set of 2D&3D interface programming criterion dependent from hardware. It is cross-platform. Later we’ll introduce in detail how to code OpenGL on Mac and simply introduce how to create OpenGL environment on Windows. And later you could try it on your own PC.
2. Mac OS X supports many different kinds of display cards, OpenGL could directly control many different kinds of graphic cards.
OpenGL controls graphic memory:
It’s known to all that malloc used C language or the “New” in C++ or alloc in Object-C all use common physical memory, which has nothing to do with your graphic memory. All space created in OpenGL API is graphic memory space. e.g. if your OpenGL application is a 3D animation, generally you will create dual caches to guarantee the continuity of the animation when switching. All the graphic memory is created directly by OpenGL application. Even when you are playing OpenGL game, the bigger your graphic memory is, the better your display effect would be. This is the answer. Therefore, later during the process writing OpenGL application, save the data to display with graphic memory as much as possible.
3. The layer of OpenGL in Mac OS X system.

The first layer: Windows system layer, controlling the display of