[Mesa-dev] [PATCH] nir: Apply fragment color clamping to gl_FragData[] as well.

[Rob Clark]

On Thu, Jul 5, 2018 at 12:49 PM, Eric Anholt <eric at anholt.net> wrote:
> From the ARB_color_buffer_float spec:
>
>    35. Should the clamping of fragment shader output gl_FragData[n]
>        be controlled by the fragment color clamp.
>
>        RESOLVED: Since the destination of the FragData is a color
>        buffer, the fragment color clamp control should apply.
>
> Fixes arb_color_buffer_float-mrt mixed on v3d.

Reviewed-by: Rob Clark <robdclark at gmail.com>

*possibly* over thinking this, the comment in the gl_frag_result enum
implies that FRAG_RESULT_DATAn come at the end of the enum (ie. if
there was somehow ever a new value added it should come before
FRAG_RESULT_DATA0).. maybe that comment should be less subtle to avoid
accidentally breaking the logic below?

BR,
-R

> ---
>  src/compiler/nir/nir_lower_clamp_color_outputs.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/src/compiler/nir/nir_lower_clamp_color_outputs.c b/src/compiler/nir/nir_lower_clamp_color_outputs.c
> index b76a4d51aaca..32f855624276 100644
> --- a/src/compiler/nir/nir_lower_clamp_color_outputs.c
> +++ b/src/compiler/nir/nir_lower_clamp_color_outputs.c
> @@ -47,13 +47,8 @@ is_color_output(lower_state *state, nir_variable *out)
>        }
>        break;
>     case MESA_SHADER_FRAGMENT:
> -      switch (out->data.location) {
> -      case FRAG_RESULT_COLOR:
> -         return true;
> -      default:
> -         return false;
> -      }
> -      break;
> +      return (out->data.location == FRAG_RESULT_COLOR ||
> +              out->data.location >= FRAG_RESULT_DATA0);
>     default:
>        return false;
>     }
> --
> 2.18.0
>