Re: Why run xserver on the OpenGL API?

On Tue, 2003-11-25 at 15:21, Jon Smirl wrote:
> --- Keith Packard <[email protected]> wrote:
> > The latter is a much stronger statement that encourages/forces application
> > developers to migrate to a strange and possibly inappropriate graphics
> > model.  Far better is to provide appropriate glue between the API they want
> > to use and the graphics hardware, let them use GL where appropriate, and
> > also provide support for cairo and xlib.  Cairo is a clean 2D API that can
> > live atop either xlib, Render or GL, and exposes a full PDF 1.4 rendering
> > model which is as close to 'complete' as we've seen in a 2D API.
> 
> My understanding is that Cairo is a retained mode interface and OpenGL is an
> immediate mode one. So we are comparing apples and oranges.  Maybe someone can
> elighten me, why is Cario being designed instead of just using the SVG API? Is
> Cairo going to be integrated with stylesheets like SVG? If not, what good is
> this to the browser developers?

it's good the same way OpenGL is good to 3D programmers, even tho models
aren't stored as a stream of OpenGL commands.  cairo provides a
powerful, flexible rendering API that could potentially allow much
easier and more efficient rendering of web-pages, even if the browser
still has to interpreter SVG/CSS/HTML/etc like they always had to.

i'm also not sure on the retained mode bit - i think it depends on the
backend.  you *could* render to a pixmap then send that to X, or you
have each individual operation work on the final (perhaps hidden)
server-side pixmap, using accelerated architecture.  just like OpenGL.

> 
> > Let the application developer select their API, and just make sure that
> > reasonable APIs map as directly to the hardware as feasible.
> 
> My goal is to ensure that OpenGL is available on every Linux desktop as soon as
> possible. A big reason we don't have Linux games is that the status of OpenGL
> support under Linux is pretty chaotic. A pervasive OpenGL API is the key to
> getting mainstream apps to use it, but it will take years of deployments before
> this happens. This says nothing about using the Cairo API, Cairo is retained
> mode which is a different beast,

This is a bit of a side-discussion, but I'd have to heartily disagree. 
Every problem I've had with Linux gaming has had nothign to do with
graphics drivers, and everything to do with that Linux/UNIX is a pain in
the ass for a non-technical.  Just try to get any recent game installed
without opening a terminal, hacking a shell script, or manually
replacing a .so file.  Good luck.  Probably the only thing most users
*will* have working easily is the graphics driver (assuming their OS
installed it).

-- 
Sean Middleditch <[email protected]>
AwesomePlay Productions, Inc.