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

[Jon Ashburn]

Okay I understand what you were doing. Perhaps if want to simplify and 
focus the test then just remove the setting of BASE_LEVEL  and MAX_LEVEL 
altogether.

I just threw that setting of MAX_LEVEL in since it would potentially 
interact with
the texture_view driver code.

Jon
On 01/13/2014 06:28 PM, Chris Forbes wrote:
> 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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