GLX

GLX

Original author(s)	SGI
Stable release	1.4
Written in	C
License	SGI FreeB License
Website	http://dri.freedesktop.org/wiki/GLX

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 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'".

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

External links

• OpenGL Graphics with the X Window System (pdf)
• SGI's GLX Project Homepage
• OpenGL.org GLX/GLU/DRI documentation website