GLX

GLX (initialism for "OpenGL Extension to the X Window System") provides the 'glue' connecting OpenGL and the X Window System: it enables programs wishing to use OpenGL to do so within a window provided by the X Window System.

History

GLX was created by Silicon Graphics and is currently at version 1.4. GLX, with both DRI and Mesa, is included in the X.Org Foundation's version of the X Window System since X11R6.7.0, and in The XFree86 Project's version since version 4.0.

Features

GLX consists of three parts:

• An API that provides OpenGL functions to an X Window System application.
• An extension of the X protocol, which allows the client (the OpenGL application) to send 3D rendering commands to the X server (the software responsible for the display). The client and server software may run on different computers.
• An extension of the X server that receives the rendering commands from the client and either passes them on to a hardware-accelerated 3D graphics card or renders them in software, usually using the Mesa library (which is much slower).

If client and server are running on the same computer and an accelerated 3D graphics card using a suitable driver is available, the latter two components can be bypassed by DRI. In this case, the client program is then allowed to directly access the graphics hardware.

A great deal of diagnostic information about GLX, including the GLX visuals the server supports, can be found using the glxinfo command. The demo utility glxgears provides a rough estimate of the speed of the 3D rendering setup. In newer versions of glxgears you have to use the -printfps switch to glxgears to see the speed.

See Also

• WGL: the equivalent Microsoft Windows interface to OpenGL
• CGL: the equivalent Mac OS X interface to OpenGL
• AIGLX
• GLUT

External links

• OpenGL Graphics with the X Window System (pdf)
• SGI's GLX Project Homepage