[Mesa-dev] [PATCH] mesa: default DepthMode to GL_RED on ES 3.0

[Ian Romanick]

On 02/16/2016 11:14 PM, Kenneth Graunke wrote:
> On Tuesday, February 16, 2016 6:29:39 PM PST Ilia Mirkin wrote:
>> See commit 9db2098d which did it internally to the i965 driver. No
>> reason not to have this more globally set though.
>>
>> This fixes depth in a bunch of dEQP EXT_texture_border_clamp tests. And
>> probably other items as well.
>>
>> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
>> Cc: Ian Romanick <idr at freedesktop.org>
>> Cc: mesa-stable at lists.freedesktop.org
>> ---
>>  src/mesa/main/texobj.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/mesa/main/texobj.c b/src/mesa/main/texobj.c
>> index d8407f0..2b9c80a 100644
>> --- a/src/mesa/main/texobj.c
>> +++ b/src/mesa/main/texobj.c
>> @@ -320,7 +320,8 @@ _mesa_initialize_texture_object( struct gl_context *ctx,
>>     obj->Sampler.MaxAnisotropy = 1.0;
>>     obj->Sampler.CompareMode = GL_NONE;         /* ARB_shadow */
>>     obj->Sampler.CompareFunc = GL_LEQUAL;       /* ARB_shadow */
>> -   obj->DepthMode = ctx->API == API_OPENGL_CORE ? GL_RED : GL_LUMINANCE;
>> +   obj->DepthMode = (ctx->API == API_OPENGL_CORE || _mesa_is_gles3(ctx)) ?
>> +      GL_RED : GL_LUMINANCE;
>>     obj->StencilSampling = false;
>>     obj->Sampler.CubeMapSeamless = GL_FALSE;
>>     obj->Swizzle[0] = GL_RED;
>>
> 
> Now I'm a bit weirded out - three years later I can't recall why I wrote
> an i965 specific patch for this.  Fixing it in core Mesa seems way
> better.  I wonder why I didn't do that in the first place.
> 
> I don't think this is quite right, though...won't this default depth
> mode to GL_RED for *all* formats?  The commit you and Ian cited explains
> that we should default to GL_RED (X, 0, 0, 1) for *sized* formats, but
> leave it as GL_LUMINANCE (X, X, X, 1) for the *unsized* ones.

I think we need to change DepthMode in GLES when the texture image is
set (by glTexImage or glTexStorage).  I think doing the mode swizzle in
the driver means glGetTexParameteriv(GL_DEPTH_MODE) will return the
wrong thing.

Defaulting to GL_LUMINANCE and possibly changing to GL_RED based on
whether or not a sized format is used for image creation should be the
right answer.

> We were sort of painted into a corner here...GLES 2 can be silently
> promoted to GLES 3...and GLES 2 already specified this as GL_LUMINANCE,
> but GLES 3 specified things as GL_RED...so there was a compromise.
> 
> Incidentally, we should figure out the GL 4.2 interaction I decided to
> put off in 2013, since we're finally there :)

Do you remember what that interaction was?

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