GLX (initialism for "OpenGL Extension to the X Window System") provides the interface 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

Silicon Graphics developed GLX; as of 2011^[update] the software has reached version 1.4. GLX, with both DRI and Mesa, has been 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 September 19, 2008, SGI created a new SGI FreeB License Version 2.0, which "now mirrors the free X11 license used by X.Org" and "meets the free and open source software community's widely accepted definition of 'free'".^[2]

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 passes them on to the installed OpenGL library (typically either a vendor-specific hardware-accelerated library or the open-source Mesa library, which as a last resort may use software rendering).

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.

See also

• WGL: the equivalent Microsoft Windows interface to OpenGL
• CGL: the equivalent Mac OS X interface to OpenGL
• AIGLX
• GLUT
• EGL: a similar cross-platform interface between OpenGL ES or VG and the underlying native platform window system

References

1. ^ http://oss.sgi.com/projects/FreeB/
2. ^ SGI Further Opens Its OpenGL Contributions

External links

• OpenGL Graphics with the X Window System (pdf)
• SGI's GLX Project Homepage^{[dead link]}
• OpenGL.org GLX/GLU/DRI documentation website