[Mesa-dev] [PATCH V3] glapi: add GL_OES_geometry_shader extension

[Tapani Pälli]

On 01/13/2016 10:29 AM, Lofstedt, Marta wrote:
>
>> -----Original Message-----
>> From: ibmirkin at gmail.com [mailto:ibmirkin at gmail.com] On Behalf Of Ilia
>> Mirkin
>> Sent: Tuesday, January 12, 2016 7:09 PM
>> To: Marta Lofstedt
>> Cc: mesa-dev at lists.freedesktop.org; Romanick, Ian D; Lofstedt, Marta
>> Subject: Re: [PATCH V3] glapi: add GL_OES_geometry_shader extension
>>
>> On Tue, Jan 12, 2016 at 9:13 AM, Marta Lofstedt
>> <marta.lofstedt at linux.intel.com> wrote:
>>> From: Marta Lofstedt <marta.lofstedt at intel.com>
>>>
>>> Add xml definitions for the GL_OES_geometry_shader extension and
>>> expose the extension for OpenGL ES 3.1.
>>>
>>> V3: Added dependency to OES_shader_io_blocks and updated to correct
>>> Khronos extension number.
>> May I ask why you did this? OES_shader_io_blocks is a purely shader
>> compiler/linker feature, I expect it will be enabled whenever GLES 3.1 is
>> enabled, no? Why would it be tied to geometry shaders? Sure, geometry
>> shaders require it to work, but just because you have OES_shader_io_blocks
>> doesn't necessarily mean you also have geometry shaders...
>>
> My intension was to address the co-dependency between oes_geometry_shader and oes_shader_io_block.
> But as always, you are right Ilia. The dependency issue need to be fixed in the driver.
>
> So, please disregard this V3, I will push the V2 with the changes suggested by Ilia in the comments.
>
> FYI here are quotes from the oes_geometry_shader specification:
> " OES_shader_io_blocks or EXT_shader_io_blocks is required."

IMO according to this it looks OES_shader_io_blocks is a valid 
requirement as that functionality is not part of OpenGL ES 3.1.

> " This extension relies on the OES_shader_io_blocks extension to provide
>      the required functionality for declaring input and output blocks and
>      interfacing between shaders."
>
> " If the OES_geometry_shader extension is enabled, the
>      OES_shader_io_blocks extension is also implicitly enabled.
>
>
>> In practical terms, there's a non-trivial chance that A4xx will get tessellation
>> before geometry shaders, which would also require OES_shader_io_blocks
>> to be exposed.
> Yes, but for desktop we already have the "shader_io_block" functionality.
> So, the dependency is a GLES issue, and tessellation is not yet exposed under GLES.
>
>>    -ilia