[Mesa-dev] [PATCH 1/1] st/mesa: Set samplers views' first_level.

[Henri Verbeet]

On 14 January 2011 16:49, Brian Paul <brianp at vmware.com> wrote:
> This isn't fresh in my head any more, but the code as-is matches the
> behaviour of NVIDIA's driver (and fixed a mipmap failure in a test
> somewhere).  The mesa-demos/src/tests/mipmap_limits test is good for testing
> this.
>
> I applied your patch and now mipmap_limits no longer matches NVIDIA.
>
Is that on any specific hardware / driver? I'll have a look at that
demo to see what happens here.

> I don't have time right now to dig into this.  Does your patch fix something
> in particular?
>
The specific bug it fixes is image array selection for linear filtered
textures with Evergreen on r600g. (There's a Wine d3d9 test that ends
up failing because of this, but it can be reproduced with a trivial GL
program as well.) When mipmapping is disabled (i.e., with LINEAR or
NEAREST filtering) min_lod / max_lod should be ignored, and the
decision of what image to use should be based purely on the texture's
base level. R600g behaves according to the spec in that regard, but
because the state tracker currently always gives us 0 for first_level
this means we always use level 0 for non-mipmapped textures.

For what it's worth, the binary nvidia driver passes that test.