[Mesa-dev] OpenGL ES only configuration (without "desktop" OpenGL support)

[Siarhei Siamashka]

On Tue, 6 Aug 2013 15:54:57 -0700
Matt Turner <mattst88 at gmail.com> wrote:

> On Tue, Aug 6, 2013 at 2:13 PM, Siarhei Siamashka
> <siarhei.siamashka at gmail.com> wrote:
> > Hello,
> >
> > Some months ago, the commit "configure.ac: Allow OpenGL ES1 and ES2 only
> > with enabled OpenGL" dropped support for the OpenGL-free configuration.
> >
> >     http://lists.freedesktop.org/archives/mesa-dev/2013-February/033909.html
> >     http://lists.freedesktop.org/archives/mesa-commit/2013-February/041708.html
> >
> > Could this be possibly reverted to allow me to continue "shooting
> > myself in the foot"? The support for OpenGL ES is pretty horrible
> > in the open source software. One nice exception is Qt5 which is doing
> > pretty well. But the rest of the software does not generally work out
> > of the box without patches or tweaks. You can also hardly find a
> > problem-free OpenGL ES compatible open source game (other than Quake3).
> >
> > I have an open feature request for Gentoo, which is a very configurable
> > Linux distribution and should not have any troubles working either with
> > or without OpenGL (the choice is up to the user):
> >
> >     https://bugs.gentoo.org/show_bug.cgi?id=476524
> >
> > But if upstream Mesa treats this configuration as unsupported, then I
> > also don't see it progressing anywhere in Gentoo. So could you please
> > re-consider this decision?
> 
> As far as I'm aware, ES without Desktop GL is disallowed only because
> it was discovered to be broken

The commit message did not mention any real problems that had to be
solved. Not sure about the other hardware, but I have been using Mesa
9.1.x with nouveau on NV86 hardware configured with "--enable-gles1
--enable-gles2 --disable-opengl" among other options. And it worked.

Based on a quick test, the current Mesa git master also can work in
ES-only mode if the following commits are reverted:

http://cgit.freedesktop.org/mesa/mesa/commit/?id=afa33a001a39c44238ba8fd76f8eeabad041459e
http://cgit.freedesktop.org/mesa/mesa/commit/?id=3479fdef2f0fe4f98828a84d0b44df5fd66e702c

> which is because no one working on Mesa appears to test it.

I have not done any really serious testing. I'm just playing around
with an old x86 laptop, where Mesa is configured without Desktop GL.
And using it for trying various software, which is supposed to be
OpenGL ES compatible. I'm also testing the same OpenGL ES software on
an ARM board with Mali400 GPU and a proprietary binary driver. Just
using the x86 laptop is a lot faster and more convenient for debugging.

If more 3D application developers could test their applications
for basic OpenGL ES compatibility using the commonly available
desktop hardware, the quality could have been much better compared
to what we have now.

That said, seems like the "embedded" hardware is also going to
eventually get full OpenGL support. It may be a bit too late to
even worry about OpenGL ES.

> If you can test it (and provide patches when you notice that it's
> broken) I don't have a problem with allowing ES-only builds.

Thanks. That's fair enough.

-- 
Best regards,
Siarhei Siamashka