[Mesa-dev] [PATCH 03/22] i965/meta: Use explicit uniform locations in fast clear shader

[Iago Toral]

On Wed, 2016-02-17 at 17:57 -0800, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_meta_fast_clear.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
> index 37dffb9..3917df1 100644
> --- a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
> +++ b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
> @@ -62,7 +62,6 @@ struct brw_fast_clear_state {
>     struct gl_vertex_array_object *array_obj;
>     GLuint vao;
>     GLuint shader_prog;
> -   GLint color_location;
>  };
>  
>  static bool
> @@ -118,7 +117,13 @@ brw_bind_rep_write_shader(struct brw_context *brw, float *color)
>        "   gl_Position = position;\n"
>        "}\n";
>     const char *fs_source =
> -      "uniform vec4 color;\n"
> +      /* GL_ARB_explicit_uniform_location requires either GLSL 3.30 or
> +       * GL_ARB_explicit_attrib_location, and only the later is universally
> +       * supported.
> +       */
> +      "#extension GL_ARB_explicit_attrib_location: require\n"
> +      "#extension GL_ARB_explicit_uniform_location: require\n"

We only use fast clears since gen6 so right now anything that goes
through this code  is going to meet this requirements. I wonder if it
would be worth it to assert on the supported GL version here, or at
least that the FS compile worked though.

> +      "layout(location=0) uniform vec4 color;\n"
>        "void main()\n"
>        "{\n"
>        "   gl_FragColor = color;\n"
> @@ -141,13 +146,10 @@ brw_bind_rep_write_shader(struct brw_context *brw, float *color)
>        _mesa_BindAttribLocation(clear->shader_prog, 0, "position");
>        _mesa_ObjectLabel(GL_PROGRAM, clear->shader_prog, -1, "meta repclear");
>        _mesa_LinkProgram(clear->shader_prog);
> -
> -      clear->color_location =
> -         _mesa_GetUniformLocation(clear->shader_prog, "color");
>     }
>  
>     _mesa_UseProgram(clear->shader_prog);
> -   _mesa_Uniform4fv(clear->color_location, 1, color);
> +   _mesa_Uniform4fv(0, 1, color);
>  }
>  
>  void