[Piglit] [PATCH 3/4] arb_texture_view: Pass correct layer index to shader

[Chris Forbes]

Could do that, but one side or the other *must* account for the view
having a nonzero MinLayer.

Colors[] is indexed based on the layer index relative to the
underlying texture; expectedLayer is currently relative to the
underlying texture; the value used in the shader needs to be relative
to the view [so expectedLayer - view's MinLayer]

Did this actually work on nvidia on master?


On Wed, Jan 15, 2014 at 5:36 AM, Jon Ashburn <jon at lunarg.com> wrote:
> see inline
>
> On 01/11/2014 05:39 PM, Chris Forbes wrote:
>>
>> We want to sample from the last layer in the view, but we were actually
>> trying to sample from a layer beyond that [by the texture's minimum
>> layer].
>>
>> This might have worked on hardware where the sampler clamps the layer
>> index before sampling [NV?], but that relies on undefined behavior.
>>
>> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
>> ---
>>   tests/spec/arb_texture_view/rendering_levels.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tests/spec/arb_texture_view/rendering_levels.c
>> b/tests/spec/arb_texture_view/rendering_levels.c
>> index ef29f78..86bf055 100644
>> --- a/tests/spec/arb_texture_view/rendering_levels.c
>> +++ b/tests/spec/arb_texture_view/rendering_levels.c
>> @@ -205,7 +205,7 @@ test_render_layers(void)
>>                 glClear(GL_COLOR_BUFFER_BIT);
>>                 expectedLayer = l + numLayers[l] - 1;
>> -               draw_3d_depth(-1.0, -1.0, 2.0, 2.0, expectedLayer);
>> +               draw_3d_depth(-1.0, -1.0, 2.0, 2.0, numLayers[l] - 1);
>>
>
> with this change  then the draw depth is inconsistent with the indexing into
> the Colors array
> how about this:
> expectedLayer = numLayers[l] - 1;
>
>
>>                 expected[0] = Colors[expectedLayer][0] / 255.0;
>>                 expected[1] = Colors[expectedLayer][1] / 255.0;
>
>
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