quote:Original post by JonnyQuest
Nit-picking here, but you said one only has register combiners in GeForce 3/4Ti, etc. which isn''t true.

Actually, for perpixel operation, it is true. All perpixel manipulations a GF3/4 can do, are either based on register combiners, or on texture shaders. The later ones can be seen as an extension to regcoms, that operate on texel fetch operations. You do not have fragment programmability (as with the FX), only fragment routing and combining, selecting from a set of predefined operations. OpenGL directly exposes this part of the hardware, while DirectX kind of disguises it into pseudo-programs, that are actually state-programs for the regcom/texshader pipeline.

That''s why, for example, you cannot feed a texel addressing operation with the results of a texel lookup on a GF3/4: the fixed regcom pipeline makes that impossible. It is however possible on an FX or Radeon 9x00.

As for vertex shaders, the GF3 is fully programmable (although more limited than newer cards, obviously).