[Mesa-dev] [PATCH 01/11] i965: Fix ctx->Texture.CubeMapSeamless

[Ian Romanick]

On 02/10/2015 07:40 AM, Eduardo Lima Mitev wrote:
> From: Iago Toral Quiroga <itoral at igalia.com>
> 
> The intel driver code, and apparently all other Mesa drivers, call
> _mesa_initialize_context early in the CreateContext hook. That
> function will end up calling _mesa_init_texture which will do:
> 
> ctx->Texture.CubeMapSeamless = _mesa_is_gles3(ctx);
> 
> But this won't work at this point, since _mesa_is_gles3 requires
> ctx->Version to be set and that will not happen until late
> in the CreateContext hook, when _mesa_compute_version is called.
> 
> We can't just move the call to _mesa_compute_version before
> _mesa_initialize_context since it needs that available extensions
> have been computed, which again requires other things to be
> initialized, etc. Instead, we just re-compute
> ctx->Texture.CubeMapSeamless after the version is known.
> 
> As far as I can see, this should affect all Mesa drivers, as it
> seems that all call _mesa_initialize_context before _mesa_compute_version.
> Separate patches can fix the problem for other drivers.
> 
> Fixes the following 190 dEQP tests:
> dEQP-GLES3.functional.texture.filtering.cube.formats.*
> dEQP-GLES3.functional.texture.filtering.cube.sizes.*
> dEQP-GLES3.functional.texture.filtering.cube.combinations.*
> dEQP-GLES3.functional.texture.mipmap.cube.*
> dEQP-GLES3.functional.texture.vertex.cube.filtering.*
> dEQP-GLES3.functional.texture.vertex.cube.wrap.*
> ---
>  src/mesa/drivers/dri/i965/brw_context.c | 6 ++++++
>  src/mesa/main/texstate.c                | 8 ++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> index e20da0b..f5b0624 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -859,6 +859,12 @@ brwCreateContext(gl_api api,
>  
>     _mesa_compute_version(ctx);
>  
> +   /* This is done in _mesa_init_texture called from _mesa_initialize_context
> +    * above, but it won't work until we have computed the GL version, so
> +    * do it again here.
> +    */
> +   ctx->Texture.CubeMapSeamless = _mesa_is_gles3(ctx);
> +
>     _mesa_initialize_dispatch_tables(ctx);
>     _mesa_initialize_vbo_vtxfmt(ctx);
>  
> diff --git a/src/mesa/main/texstate.c b/src/mesa/main/texstate.c
> index 66fd718..f03862e 100644
> --- a/src/mesa/main/texstate.c
> +++ b/src/mesa/main/texstate.c
> @@ -882,6 +882,14 @@ _mesa_init_texture(struct gl_context *ctx)
>      *     "OpenGL ES 3.0 requires that all cube map filtering be
>      *     seamless. OpenGL ES 2.0 specified that a single cube map face be
>      *     selected and used for filtering."
> +    *
> +    * FIXME: the call to _mesa_is_gles3 below will only work as intended if
> +    * the driver has already computed and set ctx->Version, however drivers
> +    * seem to call _mesa_initialize_context (which calls this) early
> +    * in the CreateContext hook and _mesa_compute_version much later (since
> +    * it needs information about available extensions), which means that this
> +    * won't actually work unless we figure out a way to compute the GL version
> +    * before _mesa_initialize_context is called.
>      */
>     ctx->Texture.CubeMapSeamless = _mesa_is_gles3(ctx);

We at least know the API at this point, right?  My recollection is that
ES2 is a imprecise in the sort of cubemap filtering you get.  Further, I
believe that some implementations have always given seamless filtering
in ES2.  It might be better to change this to

   ctx->Texture.CubeMapSeamless = ctx->API == API_OPENGLES2;

This could cause problems for drivers that can't do seamless, I suppose...