[Mesa-dev] [PATCH 01/10] mesa: add infra for ARB_shader_texture_image_samples

[Ian Romanick]

On 09/08/2015 08:10 PM, Ilia Mirkin wrote:
> On Tue, Sep 8, 2015 at 11:05 PM, Ian Romanick <idr at freedesktop.org> wrote:
>> On 08/27/2015 08:48 PM, Ilia Mirkin wrote:
>>> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
>>> ---
>>>  src/mesa/main/extensions.c | 1 +
>>>  src/mesa/main/mtypes.h     | 1 +
>>>  2 files changed, 2 insertions(+)
>>>
>>> diff --git a/src/mesa/main/extensions.c b/src/mesa/main/extensions.c
>>> index a57d5ba..1f7d542 100644
>>> --- a/src/mesa/main/extensions.c
>>> +++ b/src/mesa/main/extensions.c
>>> @@ -159,6 +159,7 @@ static const struct extension extension_table[] = {
>>>     { "GL_ARB_shader_stencil_export",               o(ARB_shader_stencil_export),               GL,             2009 },
>>>     { "GL_ARB_shader_storage_buffer_object",        o(ARB_shader_storage_buffer_object),        GL,             2012 },
>>>     { "GL_ARB_shader_subroutine",                   o(ARB_shader_subroutine),                   GLC,            2010 },
>>> +   { "GL_ARB_shader_texture_image_samples",        o(ARB_shader_texture_image_samples),        GL,             2014 },
>>
>> I'm not sure we can expose this yet.  The spec says:
>>
>>     "Dependencies
>>
>>         OpenGL 4.3 is required.
>>
>>         OpenGL Shading Language 4.30 is required"
>>
>> I wasn't involved with the development of this spec at all, so I don't
>> know why the requirement is so high.  Images were added in 4.2.
>> Certainly every other implementation that has this extension will also
>> have 4.3 or higher.
>>
>> It seems weird since the related extensions only require 4.2
>> (GL_ARB_shader_image_size) or 3.1 (GL_ARB_texture_multisample).
>>
>> Since you have tests... do you know what other implementations do if you
>> only have #version 130?  If nobody enforces the #version 430 requirement
>> from the spec, I'll propose some changes to the spec.
> 
> FWIW we ignore these (IMHO silly) version requirements on almost every
> extension that has them. I know I've personally added support for
> EXT_polygon_offset_clamp into compat contexts, whereas the ext
> specifies GL 3.3 minimum.

Sometimes the dependencies are real, but this one does seem spurious.

> I'll give it a shot on NVIDIA and see what happens... my tests might
> require GL 3.2 because I didn't want to deal with the various
> differences that happen otherwise.

That should be good enough.  Perhaps someone else can try on AMD
closed-source drivers.  If they both ignore the spec, then I feel pretty
comfortable ignoring it too... while I work on getting it changed.

>   -ilia