Xegl lives!

[Jon Smirl]

On 5/24/05, Allen Akin <akin at pobox.com> 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.
> 
> For example, "draw an outline glyph with subpixel positioning and
> antialiasing using a Porter-Duff composition operator" may cause
> problems, because very high quality antialiasing of arbitrary geometry
> requires multipass rendering (even with high-end accelerators), and the

Allen, I've always been suspicious that the Cairo imaging model wasn't
really compatible with the OpenGL one but I lack the background to
make a true comparison. Are the models really compatible?

One of the facts we have to live with is that we have accelerated
OpenGL/D3D hardware and thanks to Longhorn were going to get a whole
lot more of it. We're not likely to get Cario hardware so we're forced
to live in the OpenGL/D3D world. I hope that Cairo maps efficiently to
this hardware but I haven't seen convincing evidence proving this is
possible.

If we had started with OpenGL and worked backwards to produce a Cairo
like API, how would it be different? I've always been worried that
starting with software rendering and then porting to OpenGL could
easily produce something that wouldn't map efficiently onto the
available hardware. Software rendering lets you pick any algorithm
while very few algorthims work well in hardware.

BTW, I do support the Cairo effort. We obviously needed a 2D API that
could print.

-- 
Jon Smirl
jonsmirl at gmail.com