I use many indirections in my fragment programs.
Most of the time, I use textures as Look-Up-Tables and I simply use bilinear interpolation.
But, sometimes, I use the contents of a first texture to offset/rescale the coordinates of a second texture.
In such a case, I need to use Mipmap and/or anisotropic filtering to avoid texture-fragment-program-aliasing.
I just cannot figure out how the Mipmap levels are calculated by the GPUs in such cases.
The link between the "tex coordinate generator" and the "tex sampler" is indirect. And so, their link is no more explicit.
So, how the compiler/GPU links the MipMap level (or more precisely, the texture coord gradient, calculated by the "tex coord unit" along with tex coords afaik) to the "tex sampler" ?
Is there an implicit mechanism ?
I read somewhere that DX PS3.0 allowed to access gradient information...
Maybe it is possible to use TXB in some way, but how ?
Arrrg, I have got an headache.
I tried to find documents or part of documents about this topic but I did not find any.
So I will be gratefull if anybody had a clue on this topic.