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OpenGL
Windows NT supports the industry-standard graphics language known as OpenGL. OpenGL provides a software interface for creating two-dimensional and three-dimensional graphics. The only difference between OpenGL in Windows NT and Unix and other Windows implementations is that Windows NT supports VGA 16-color mode graphics.

Several OpenGL screen savers ship with Windows NT. Although these savers are good examples of the OpenGL capabilities, they are also quite resource intensive. You should not implement them on production file, print, or application servers.


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The OpenGL screen savers contain several “Easter eggs.” Two of the better-known Easter eggs are as follows:
  1. The OpenGL 3D Text screen saver has several hidden message text strings over the versions of Windows NT. Windows NT 4 includes an Easter egg that displays all the volcanoes located in Washington. To view these volcano names, set the text field to “volcano” as shown in Figure 5.8. This causes the screen saver to display a random list of volcanoes.
  2. The OpenGL Mixed Pipes screen saver has another Easter egg hidden within its settings. If you set the joint type to Mixed in the 3D Pipe screen saver settings, the screen saver periodically draws a teapot as an elbow joint. Figure 5.9 shows the settings for this.
Windows NT supports the following three graphics modes for OpenGL:
Software rendering mode enables OpenGL to work with any Windows NT-supported video adapter. All OpenGL calls are executed using the Windows NT GDI. This mode does not take advantage of accelerated video cards.

3D accelerated mode is required when the user need to do serious graphics work such as animation or computer aided design (CAD). In this mode, graphic card vendors provide device drivers optimized for performance of OpenGL applications. The 3D drivers convert OpenGL calls to functions supported on the video card. This removes the execution from software calls to the actual hardware, resulting in a performance gain.

OpenGL accelerated mode is used by Windows NT Workstation when the workstation has workstation-class 3D graphics hardware. These adapters contain 3D OpenGL functionality, and any OpenGL calls are passed straight to the hardware. This is the best performing mode for OpenGL support because it removes all execution from software to hardware.