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List:       freedesktop-xorg
Subject:    Re: Xegl lives!
From:       Matthias Hopf <mhopf () suse ! de>
Date:       2005-05-25 11:11:15
Message-ID: 20050525111115.GC28717 () suse ! de
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On May 24, 05 20:39:29 -0700, Allen Akin wrote:
> On Tue, May 24, 2005 at 05:15:04PM -0400, Jim Gettys wrote:
> | Believe it or not, GL doesn't do everything needed for 2D graphics....
> | Subpixel text, for one, though Allen Akin was scratching his head to see
> | if he could figure out how.
> 
> Text is plenty doable, but the crux of the matter is what rendering
> model you choose to expose.

Actually, in order to get subpixel rendering right even with compositing
(which could arbitrarily scale intermediate output) only multisampling
approaches will work. That will kill a lot of bandwith and GPU memory,
so a less-than-perfect but usable alternative solution would be good.

BTW - this has nothing to do with OpenGL, it is just that subpixel
rendering and compositing doesn't mix well.

Using multisampling or higher resolution intermediate images and
rendering them subpixel correct in the composition step should be doable
with fragment programs, though not easy, as you cannot transfer state
from one pixel to the next. This sound something like what Zack
explained for Avalon, but to do it right it should be performed as the
very last step in the rendering pipeline.

Antialiasing is less an issue, filtering again already filtered
intermediate images will increase blur a bit, but results will remain
essentially correct.

And before I forget: Nice work, Jon :)

Matthias

-- 
Matthias Hopf <mhopf@suse.de>       __        __   __
Maxfeldstr. 5 / 90409 Nuernberg    (_   | |  (_   |__         mat@mshopf.de
Phone +49-911-74053-715            __)  |_|  __)  |__  labs   www.mshopf.de

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