Hi
Fedora Rendering Project (http://fedoraproject.org/wiki/RenderingProject) hit slashdot today and osnews before that.
http://linux.slashdot.org/linux/06/02/22/1638228.shtml
http://osnews.com/comment.php?news_id=13734
Rahul Sundaram sundaram@fedoraproject.org wrote:
Hi Fedora Rendering Project (http://fedoraproject.org/wiki/RenderingProject) hit slashdot today and osnews before that. http://linux.slashdot.org/linux/06/02/22/1638228.shtml http://osnews.com/comment.php?news_id=13734
nVidia's Whitepaper arguing for Render/Composite atop of DDX instead of the Xgl server was enlightening. I always (and incorrectly) assumed nVidia would be for the latter. But then I quickly realized why that while they did give kudos to Xgl, they clearly prefer the former -- for a variety of reasons, and not just selfish ones either. Some are very sound, technically.
First there is the difficulty of Xgl not address hardware-specific details like multi-card/multi-display with the same driver/buffer. An entire new set of APIs would need to address that, which have not, and sometimes that's just not feasible with various hardware out there. Especially when new support is needed that was not previously thought of. In other words, the Xgl is "too generic" of a server between the hardware and the end-user, where the end-user knows what monitors and (possibly) cards are in use, but Xgl doesn't (at least not directly). I never, ever thought of that before, but now I totally understand why it's a major issue. It makes far more sense for X and server driver to be integrated whereas Xgl makes too much far too arbitrary.
Secondly, it does force OpenGL on everyone. Not only does not everyone have a capable accelerated OpenGL driver for X, but not all OpenGL is created equal (especially chipset-integrated) for that matter. I personally like their comment -- Xgl essentially makes the desktop the "lowest common denominator," and that's pretty low in the case of many vendors who are well behind even OpenGL 1.3 (let alone 2.0).
Lastly, and most interestingly coming from nVidia, sometimes you just don't want to use OpenGL at all. Most people forget that nVidia does provide a good amount of work into the MIT licensed 2D drivers that come with XF86/Xorg, and the new Xorg X11R7+ model will make updates much easier. nVidia is _not_ just thinking about their proprietary drivers here. They are considering that Render/Composite doesn't have to be OpenGL, and there might be many cases when you don't want it.
Given what was said in the whitepaper, I'm looking forward to both MIT licensed "nv" driver developments in Xorg X11R7+ was well as nVidia "nvidia" driver developments in ForceWare 85. The cool thing is that in _any_case_, nVidia is supporting _all_ developments -- AIGLX, Xgl, Looking Glass, etc... But it's clear that not only their preference is on the Render/Composite approach and working with AIGLX from their perspective, but that its more beneficial for even other drivers, including 2D-only hardware support.
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