[Mesa-dev] [PATCH 1/2] glsl: always enable OES_standard_derivatives features if supported

[Timothy Arceri]

On 16/05/18 22:09, Ilia Mirkin wrote:
> On Wed, May 16, 2018 at 8:04 AM, Timothy Arceri <tarceri at itsqueeze.com> wrote:
>>
>>
>> On 16/05/18 21:12, Ilia Mirkin wrote:
>>>
>>>   From the spec,
>>>
>>> """
>>>       The built-in derivative functions dFdx, dFdy, and fwidth are
>>> optional, and
>>>       must be enabled by
>>>
>>>       #extension GL_OES_standard_derivatives : enable
>>>
>>>       before being used.
>>> """
>>>
>>> Sounds like you need an application override?
>>
>>
>> The ES spec has no such wording is simply states:
>>
>> "dFdx(), dFdy(), and fwidth() are made optional."
> 
> That is under the heading of "Changes from Revision 59 of the OpenGL
> Shading Language specification:", i.e. desktop GLSL.
> 
> There isn't a single other reference to those functions anywhere else
> in https://www.khronos.org/files/opengles_shading_language.pdf . The
> "optional" is in reference to it being moved out to an extension
> rather than being part of the core language.

It also says noise is optional but there is no spec for it that I can see.

> 
>    -ilia
>