3.3 OpenGL's Connection to the Windowing-System

OpenGL is specified as a 3D rendering machine. To view the rendering results, we need an visual output device, e.g. the monitor ;-). To simplify the monitor output OpenGL uses an existing operating system, which allows graphical output on the screen. The X-Window-System or MS-Windows is a well known an often distributed graphical interface, where the X-Window-System is avaiable on many platforms. The common tasks, means the minimum need, of a library which connects the OpenGL machine to the Windowing-System are:

• connect the OpenGL machine to a window
  • create a window
  • connect the window handel to the OpenGL handle/context
  • set up the window properties, e.g. colors
  • close the window
• re-rendering with OpenGL when the window must be refreshed

See the java class implementation in chapter 5.13 on page to find the platforms window handle.

3.3.1 X-Window-System

OpenGL's interface to the X-Window-System (X)[4] is the GLX library. The GLX library[2] can connect the OpenGL machine^c to X. GLX supports all criteria specified above.

3.3.2 MS-Windows

OpenGL's interface to MS-Windows (MSW) is the WGL library. The WGL library[3] can connect the OpenGL machine^d to MSW. MSW supports all criteria specified above.

Footnotes

... machine^c

a instance of the OpenGL machine, the OpenGL context - in detail

... machine^d

a instance of the OpenGL machine, the OpenGL context - in detail