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Re: Bug#881333: Qt with GLES on arm64 maintainer's decision - Was:: Upcoming Qt switch to OpenGL ES on arm64

On Mon, Nov 26, 2018 at 03:39:03PM -0800, Keith Packard wrote:
> Steve Langasek <vorlon@xxxxxxxxxx> writes:

> > Long ago I heard rumors of development work on mesa that would allow it to
> > function as a proxy library, so that apps would link against libGL as needed
> > and the GL implementation would use a hardware-accelerated GLES driver where
> > possible, falling back to software GL where necessary.

> This seems unlikely -- I believe GLES and GL have different semantics in
> a few places which makes implementing GL on GLES inefficient; mostly
> that GLES is missing stuff that GL applications often use, but I think
> there are places where GLES is just different, including in how GLSL
> works.

Perhaps that explains why no one ever actually succeeded in implementing it,

Thanks for the context.

> I haven't tried, but I would expect that applications could use both GL
> and GLES APIs at the same time, even to the same window. If this does
> work with Mesa, then linking Qt against GLES wouldn't restrict
> applications using free drivers at least?

My recollection is that this becomes a practical problem of applications
that want to use both Qt and GL being unbuildable due to namespace
collisions at build time.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek@xxxxxxxxxx                                     vorlon@xxxxxxxxxx

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