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

[Chris Forbes]

You're right, this one is a bit odd, and the commit message didn't
really explain what I was getting at...

Most of what I was trying to do here is eliminate the hardware lod
selection as a complicating factor -- since we're really testing that
levels are view-relative. It's possible that I've misunderstood what
you were trying to do though and destroyed the essence of it. What do
you think?

On Tue, Jan 14, 2014 at 1:58 PM, Jon Ashburn <jon at lunarg.com> wrote:
> 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);
>>
>
>
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