i’ve been through the forum history, and it seems like this should be possible, but there is no pseudo-code to guide me…
i am interested in doing a pre-filtered dependent texture lookup (8-bit -> RGBA), but still outputting filtered texels (exactly the behavior of EXT_paletted_texture, but using register combiners or other…). i also want to know if this is possible on NV2x hardware.
i can obviously bind the texture to one unit with NEAREST filtering, and do a dependent fetch, but then the texture is aliased and blocky, since it has not been smoothed with linear filtering. so is there a way, after the dependent fetch, to somehow filter the texture properly?
ultimately, what i am trying to do is masked multitexturing, with an arbitrary base texture in unit 0, and an 8-bit mask texture in unit 1. the result being that the mask is used to modulate on a per-pixel basis the color and opacity of the base texture.
one way to do this is to just bind an RGBA texture to unit1 and do a simple TexEnv modulate, but this is very expensive when the mask changes, and uses tons of memory unnecessarily for 3D textures.
actually, i seem to remember seeing somewhere in the docs or presentations on nvidia’s site an example where a texture was filtered nearest neighbor in one direction, and linear in the other (i can’t remember where i saw it! doh!). this is along the lines of what i want to do.