Linked by Thom Holwerda on Sat 19th Aug 2006 22:32 UTC
X11, Window Managers "In the last few months, there has been a lot of talk about Xgl, compiz, AIGLX et cetera. It seems that 'Xgl' has become a synonym for fancy desktop on Linux - but no one seems to talk about the alternatives or how it all works. I have had a little look into this and am going to summarize it for y'all. I will explain where the following come from and how they work: Xglx, Xegl, Luminocity, and AIGLX."
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Wrong
by subterrific on Mon 21st Aug 2006 18:10 UTC
subterrific
Member since:
2005-07-10

The article's comments on Xegl are almost all wrong.

"Xegl uses EGL (embedded openGL), a kernel-level OpenGL API."

EGL (aka OpenGL ES) is no more kernel-level than OpenGL. It is simply an API specification. From the Khronos Group: "OpenGLŪ ES is a royalty-free, cross-platform API for full-function 2D and 3D graphics on embedded systems"

"Xegl shares much the same problems as Xglx: by relying fully on OpenGL, it neglects special features a graphics card might have (e.g.: Multihead support, special shader APIs)."

This is wrong again. OpenGL and EGL both allow for vender extensions to support special hardware features. At runtime you can test for extensions before using them. Quake3 does this, for example. There is also nothing preventing Multihead support in the EGL API.

EGL is designed to support implementing a windowing system on top of it. This means it has APIs for mode switching: eglChooseConfig, multihead: eglGetDisplay. It has the advantage of being built on top of OpenGL, so there are existing full software implementations (Mesa) from which hardware developers can slowly add hardware acceleration.

It is not some unknown, unsupported API:

http://www.khronos.org/opengles/adopters/adopterslist/

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