Multi Pass Rendering

Hi!

I am trying to do Bump Mapping using NVIDIA’s register combiners. I only have 2 Texture units and 2 Combiners and I want to implement the equation “[DecalRGB x (N.L)] + [Gloss x (N.H)4]”
What is the best and efficient way to do it ?

Also how to do:

Say in the first pass I rendered DecalRGB to the FrameBuffer or Accumulation buffer and now if I go about to render (N.L), how do I achieve the multiplication operation below:
DestinationRGB = DestinationRGB x SourceRGB;

Thanks!
Arun.

glEnable(GL_BLEND);
glBlendFunc(GL_DEST_COLOR, GL_ZERO); // ??

For the first part of your question read this, it’s really an advanced topic:

http://developer.nvidia.com/object/bumpmappingwithregistercombiners.html