What are the advantages or disadvantages of using NV_register_combiners over ARB_texture_env_combine? What are the situations where one would decide to use one over the other? Is it that register combiners allow you to do the combining before it is bound to a texture unit? I’m confused about which to use. Thanks.
And of course, NV_xyz only works on NVIDIA hardware. Otherwise I think it’s more general than texture environments (though in most cases you can do the same thing with both).
I think stuff like bumpmapping is not possible with texture combiners.
Well, at least i never tried it (and i am quite sure the reason was, that it´s not possible).
However, if you understand the one, than you also will understand the other extension. And then you will know, what is possible with each one.