[Mesa-dev] Extension help

[Fritz Koenig]

On Fri, Aug 2, 2019 at 3:03 PM Ian Romanick <idr at freedesktop.org> wrote:
>
> On 8/2/19 1:13 PM, Fritz Koenig wrote:
> > Hi,
> >
> > I would like to be able to use the MESA_framebuffer_flip_y extension
> > in GLES 3.0.  The blocker is that FramebufferParameteri is not part of
> > GLES 3.0.  I have explored a couple of ways of achieving this.
> >
> > 1.   FramebufferParameteri was first provided by the GL extension
> > ARB_framebuffer_no_attachments.  However,
> > ARB_framebuffer_no_attachments was never a GLES extension.  An option
> > would be to modify the ARB_framebuffer_no_attachments spec to make it
> > an extension for GLES.
> >
> > 2.  Change the MESA_framebuffer_flip_y spec to allow the extension to
> > implement FramebufferParameteri.
>
> GLES has more strict rules about what functions can be advertised than
> desktop OpenGL.  Since glFramebufferParameteri is part of the reserved
> namespace, I'm not 100% sure that it's legal to expose it in pre-3.1.  I
> would suggest making a PR to the registry first.
>
I have opened a pr with Khronos.
https://github.com/KhronosGroup/OpenGL-Registry/pull/289

> My gut tells me you're going to have to add a FramebufferParameteriMESA
> function that is an alias of FramebufferParameteri.
>
Thanks for the feedback.  I was hoping to be able to drop in
FramebufferParameteri, but I believe you are correct that I need
FramebufferParameteriMESA.

> Has this extension already shipped in a Mesa release?
>
Yes, it has was present in Mesa 19

> > I choose the 2nd option and put together a pr for it[1].
> >
> > I didn't get the implementation quite right, and I'm looking for some
> > help.  My change is failing the DispatchSanity_test.GLES3 test:
> >
> > [ RUN      ] DispatchSanity_test.GLES3
> > ../src/mesa/main/tests/dispatch_sanity.cpp:174: Failure
> >       Expected: nop_table[i]
> >       Which is: 0x563d50d6fa01
> > To be equal to: table[i]
> >       Which is: 0x563d50db158a
> > i = 888 (FramebufferParameteri)
> > ../src/mesa/main/tests/dispatch_sanity.cpp:174: Failure
> >       Expected: nop_table[i]
> >       Which is: 0x563d50d6fa01
> > To be equal to: table[i]
> >       Which is: 0x563d50db1add
> > i = 889 (GetFramebufferParameteriv)
> > [  FAILED  ] DispatchSanity_test.GLES3 (1 ms)
> >
> > It appears there is a problem with the way that I'm
> > defining/redefining FramebufferParameteri.  I've tried adding it to
> > src/mapi/glapi/gen/es_EXT.xml, but the only way I was able to achieve
> > that was to give it a different function name and an alias.
> >
> > Does anyone have experience with this sort of backporting of
> > extensions that could offer some insight on what I might be doing
> > wrong?
> >
> > Thanks.
> >
> > -Fritz
> >
> > [1]: https://gitlab.freedesktop.org/mesa/mesa/merge_requests/1560
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> >
>