[Mesa-dev] [PATCH 1/2] mesa: Implement GL_ARB_texture_filter_anisotropic

[Adam Jackson]

On Thu, 2017-08-24 at 23:27 -0700, Kenneth Graunke wrote:

> > diff --git a/src/glx/glxextensions.h b/src/glx/glxextensions.h
> > index 21ad02a44b..2a595516ee 100644
> > --- a/src/glx/glxextensions.h
> > +++ b/src/glx/glxextensions.h
> > @@ -101,6 +101,7 @@ enum
> >     GL_ARB_texture_env_combine_bit,
> >     GL_ARB_texture_env_crossbar_bit,
> >     GL_ARB_texture_env_dot3_bit,
> > +   GL_ARB_texture_filter_anisotropic_bit,
> >     GL_ARB_texture_mirrored_repeat_bit,
> >     GL_ARB_texture_non_power_of_two_bit,
> >     GL_ARB_texture_rectangle_bit,
> 
> Hi Adam,
> 
> I've never seen new GL extensions added to the GLX code like this.  As
> far as I know, we haven't done that for any of the other extensions we've
> added over the last few years.  I guess this is something related to
> indirect GLX?  What does it do?  Should we drop it?

That I touched the GLX code with this change is kind of accidental, as
I was merely grepping for the EXT string. But since I did...

Yes, it's about indirect GLX. Early in GLX setup the client library
sends the server (among other things) the list of GL extension strings
it supports. glGetString(GL_EXTENSIONS) in an indirect context is then
the intersection of the client-support list and the list supported by
the indirect renderer. Since this extension's GLX support is trivial we
can just claim we support it and be done.

I suspect the reason we don't touch this list very often is that the
indirect code only implements through GL 1.4 at the moment, so the set
of extensions you can usefully enable is pretty limited. 

That said, that list has a convention for aliases that I'd missed on
first writing. I'll fix that up and merge.

- ajax