SGI open sources OpenGL Sample Implementation

Linux gets free access to closest thing to 'official' OpenGL implementation

SGI has released its OpenGL Sample Implementation (SI) under an open source licence. Of course, this isn't the same thing as releasing OpenGL itself as open source. The SI appears to be technology that supports the OpenGL API, much as Mesa, the open source alternative to OpenGL, does. SI and Mesa do what OpenGL does, but not 'officially'. However, applications talk to them just as they would to 'official', licensed implentations of OpenGL. Still, short of releasing OpenGL itself to the open source community this is probably as good as it gets. Open sourcing OpenGL would eliminate SGI's licensing revenue strand, so it's unlikely to happen for the time being. In any case, there may well be patent issues that prevent OpenGL being released under the GNU Public Licence or something similar. However, the opening of SI should enable hardware driver writers to produce better code. Drivers written to the SI should, according to SGI, be as near to OpenGL compliant as they can be without going through SGI's official compliance testing procedures. SGI last year released source code for GLX, which hooks the X Window windowing system, itself the basis for Linux's key GUIs, into OpenGL. The arrival of SI should also encourage the development of professional 3D graphics applications on Linux. Where this leaves Mesa is, however, another matter. Providing the same features as Mesa, SI is likely to arrive in a more complete form than Mesa, which remains a work in progress and, perhaps more to the point, not fully OpenGL compliant (though it's damn close). Interestingly, SGI is playing it very cautious here. Its SI FAQ suggests that Mesa will continue to have a role, primarily in the development of software renderers, which are likely to be too slow to be practical under the existing SI. Of course, as hardware acceleration becomes ever more commonplace, software rendering -- and, by extension, Mesa itself -- will become less relevant. SGI clearly appreciates this and its FAQ holds out the possibility of merging the two development programmes. That's not going to happen yet, and SGI reckons drivers for both OpenGL API implementations will exist side-by-side for some time. Of course, today's announcement also suggests that the proposed Linux version of OpenGL 1.2, to be developed by Nvidia, SGI and VA Linux Systems won't be quite as open as you might expect. ® Related Story id Software's Carmack calls for OpenGL watchdog

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