GLX (initialism for "OpenGL Extension to the X Window System") provides the binding 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.
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.
On Sept. 19, 2008, SGI created a new SGI FreeB License Version 2.0, which "now mirrors the free X11 license used by X.Org" and now "meets the free and open source software community's widely accepted definition of "free"".[2]
GLX consists of three parts:
If client and server are running on the same computer and an accelerated 3D graphics card using a suitable driver is available, the former 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 -info switch to glxgears to see the speed. Although often used as such, glxgears is not a benchmark tool. It can, however, be used to verify that hardware-accelerated libraries are installed correctly.