[Mesa-dev] [PATCH] mesa: enable tessellation on GL 4.0 and above

[Timothy Arceri]

On Sun, 2015-12-06 at 22:26 -0500, Ilia Mirkin wrote:
> On Sun, Dec 6, 2015 at 10:19 PM, Timothy Arceri
> <timothy.arceri at collabora.com> wrote:
> > On Sun, 2015-12-06 at 22:07 -0500, Ilia Mirkin wrote:
> > > On Sun, Dec 6, 2015 at 10:05 PM, Timothy Arceri
> > > <timothy.arceri at collabora.com> wrote:
> > > > ---
> > > >  src/mesa/main/context.h | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/src/mesa/main/context.h b/src/mesa/main/context.h
> > > > index 8b64f45..f3d42cb 100644
> > > > --- a/src/mesa/main/context.h
> > > > +++ b/src/mesa/main/context.h
> > > > @@ -361,7 +361,7 @@ static inline GLboolean
> > > >  _mesa_has_tessellation(const struct gl_context *ctx)
> > > >  {
> > > >     return ctx->API == API_OPENGL_CORE &&
> > > > -          ctx->Extensions.ARB_tessellation_shader;
> > > > +          (ctx->Version >= 40 || ctx
> > > > ->Extensions.ARB_tessellation_shader);
> > > 
> > > Under what circumstances would this matter? If you're faking a GL
> > > version, probably better not to pass in unexpected shader types
> > > to
> > > the
> > > driver, no?
> > > 
> > 
> > Well the GL CTS expects to access glPatchParameter* or else it
> > won't
> > run any tests for 4.0 or above.
> > 
> > Is there any difference in passing the driver unexpected shader
> > types
> > verse unexpected shader language/features?
> 
> Well, people routinely do things like force-enable higher GL versions
> because certain software incorrectly requires them despite only
> needing a handful of the extensions. Couldn't you get around this by
> doing MESA_EXTENSION_OVERRIDE=GL_ARB_tessellation_shader ?

Sure I was just trying to avoid typing

MESA_GL_VERSION_OVERRIDE=4.40 MESA_GLSL_VERSION_OVERRIDE=440
 MESA_EXTENSION_OVERRIDE=GL_ARB_tessellation_shader

Anyway I don't really care to much I have it locally now, so if it
doesn't save anyone else some trouble then I'm not worried about
pushing this.

> 
> I guess I'm not too against this, but it seems to be designed for
> partially papering over some issue that exists with just one driver.
> I
> think most places we don't have the explicit version check.
> 
>   -ilia
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