[vtkusers] OpenGL questions about Register combiners for NVIDIA board

[Jianlong Zhou]

Hi,

I am using OpenGL and the register combiners approach for programming volume 
rendering. My graphics card is Geforce 4. I hope someone who use this kind of board and 
OpenGL can answer my questions.

I have a question about register combiners and pixel transfers / dependent 
textures.
I calculate a specific value using register combiners and store it in texture2. 
Now I do not want to use this value directly but use it as an index for pixel 
transfer. Is it possible to specify a pixel transfer mapping during register 
combiner operations? I think about the following scenario: The register 
combiners calculate value X and while storing it in texture2 the pixel mapping 
takes place and the mapped values (using glPixelMapfv
(GL_PIXEL_MAP_I_TO_G,...) ) are stored. Is this possible?
If not - can I combine register combiners and dependent texures? So I compute X 
and store it in texture2 - and use texture 3 afterwards in a way that texture2 
is the index for texture3... Is this realistic or is it impossible?
I hope I could describe my problem! Thanks for the answers,

Best regards,

Jianlong