[Mesa-dev] [PATCH] softpipe: Take all lods into account when texture sampling.

[Olivier Galibert]

On Tue, Jun 19, 2012 at 02:46:35PM -0700, Jose Fonseca wrote:
> Could you give more background on why is this necessary?
> 
> This will make software renderering slower, so I'd really like to avoid it on llvmpipe if at all possible.

Well, given the existence of textureLod and textureGrad every texture
sample can easily hit a different mipmap or even, by switching between
minification and magnification, a different filter entirely.  Even a
simple texture() is hit, if your polygon is horizontal enough.

And this goes double for vertex shaders, where texture fetches there
have less reason to be close in texture space.

textureSize and textureFetch, with their explicit lod, have of course
the same problem. only worse.

  OG.