Xegl lives!

Adam Jackson ajax at nwnk.net
Wed May 25 19:43:55 PDT 2005


On Wednesday 25 May 2005 21:47, Dave Airlie wrote:
> > OpenGL-ES is designed to run on the ARM. That flavor of OpenGL
> > supports integer only operation. There are several OpenGL-ES stacks
> > for the ARM but none are free. Xgl should run on OpenGL-ES but it may
> > need some tweaks.
>
> What OpenGL interfaces does OpenGL have that OpenGL-ES doesn't?

Quads and quad strips, non-2D textures, etc.  I don't know of a comprehensive 
list of what got cut out though.  Also it depends which GLES profile you're 
using.

> is glitz targeted at OpenGL rather than OpenGL-ES

Yes.

> if I take a commerical OpenGL-ES implementation and add the screen setup
> stuff will it work? 

Not with glitz in its current form.

> it's just something that popped into my head, does OpenGL-ES provide
> full OpenGL interface and just add its own stuff like a glx/agl/wgl or
> is it a modified OpenGL interface?

OpenGL|ES is the project that spawned the EGL windowing API that we're 
stealing.  However nothing guarantees that you're running the embeddable 
subset just because you're using EGL.

The GLES spec seems to specifically allow running full OpenGL with the EGL 
bindings.  glGetString(GL_VERSION) normally returns "1.5" on full GL 
implementations, but will return "OpenGL ES-CM 1.1" or "OpenGL ES-CL 1.1" 
when running on the common or common-lite profiles of the embeddable subset, 
respectively.

> I'd hate to be calling our project egl when it is more egl-like than egl...

If it makes you feel better, you can read the "E" as "Extreme" instead of 
"Embedded". ;)  There's a reason this list has "egl" in the name, instead of 
"gles".  The hard part of bringing up X on GL is not the GL bit, likewise 
GLES is not especially difficult to acheive when you already have GL.  The 
glue between your GL and your X server - or arbitrary other native application 
- is the interesting bit.

The diatribe about how the only valid DDX for X is the GL-based one is wholly 
offtopic for dri-egl@ (so please stop); Jon mentioning GLES as though it were 
relevant to that discussion is a stunning bit of misdirection.

- ajax
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