[Piglit] [PATCH 2/4] arb_texture_view: Constrain accessible mip levels correctly

[Jon Ashburn]

Hey Chris:

I think the texture level used should be clamped when using immutable 
texture so if
the MAX_LEVEL is out of range it shouldn't matter.  Also an unset 
BASE_LEVEL should default to 0
which is relative to the view.

 From arb_texture_storage:
"

Redefine level_base, level_max to be clamped forms of
         TEXTURE_BASE_LEVEL/TEXTURE_MAX_LEVEL when using immutable
         textures
"

Which appears to be implemented here in Mesa code:
     /** From ARB_texture_storage:
        * However, if TEXTURE_IMMUTABLE_FORMAT is TRUE, then level_base is
        * clamped to the range [0, <levels> - 1] and level_max is then clamped to
        * the range [level_base, <levels> - 1], where <levels> is the parameter
        * passed the call to TexStorage* for the texture object.
        */
       if (texObj->Immutable)
           texObj->MaxLevel = CLAMP(params[0], texObj->BaseLevel,
                                    texObj->ImmutableLevels - 1);
       else
          texObj->MaxLevel = params[0];


Jon
On 01/11/2014 05:39 PM, Chris Forbes wrote:
> The test expects us to be sampling from the smallest miplevel accessible
> in the view, but the TEXTURE_MAX_LEVEL constraint was out of range,
> and TEXTURE_BASE_LEVEL wasn't set at all.
>
> This would have been masked previously because the test fell over due to
> use of legacy features in the core profile.
>
> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
> ---
>   tests/spec/arb_texture_view/rendering_levels.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tests/spec/arb_texture_view/rendering_levels.c b/tests/spec/arb_texture_view/rendering_levels.c
> index 7f02613..ef29f78 100644
> --- a/tests/spec/arb_texture_view/rendering_levels.c
> +++ b/tests/spec/arb_texture_view/rendering_levels.c
> @@ -94,7 +94,8 @@ test_render_levels(void)
>   		glTextureView(new_tex, GL_TEXTURE_2D, tex,  GL_RGBA8, l,
>   			      numLevels[l], 0, 1);
>   		glBindTexture(GL_TEXTURE_2D, new_tex);
> -		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, levels-1);
> +		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, numLevels[l] - 1);
> +		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, numLevels[l] - 1);
>   
>   		glClear(GL_COLOR_BUFFER_BIT);
>