Normally, the client and server run on the same system. OpenGL supports both an immediate mode and a retained mode for graphics operations. In the immediate mode, an application sends graphics commands to OpenGL, which promptly executes them. This provides a quick response to any changes to an image, a critical feature for interactive graphics applications. In the retained mode, sequences of graphics commands are stored in data structures known as display lists .
Display lists have two important advantages.
First, if you must display a complex object frequently, you only have to reference its display list. Second, they let object information be shipped quickly through a network. A disadvantage is that frequent modifications to an object require generating new object desc riptions. It is available on workstations and Windows. OpenGL supports a wide range of graphics environments that cover the spectrum in terms of cost and performance.