Basic 3D Understanding

[sir doris]

I'm finding much of the discussion on these boards at the moment fascinating. I understand most of what is being said to a certain extent, however I’m a bit confused as to the difference between "single pass" and "single cycle" in regard to multi texturing. I assume a "cycle" to mean a clock cycle of the GPU, but this is also what I assumed a pass to be. Could someone please clarify the difference for me?



Thx...

 

[KimB]

Basically doing it "in a single pass" means that only one framebuffer write is done.

That is, all the calculation is done internally, over however many clocks it takes, until the GPU is ready to output a color value for that pixel. That is one pass. Multipass rendering requries multiple color values to be outputted for each pixel.

 

[sir doris]

thanks a lot, all makes sense now

 

[RussSchultz]

Multipass rendering requries multiple color values to be outputted for each pixel....

....and read back in on the next pass for the rest of the caculations. Precision could be lost when writing to the frame buffer since the frame buffer is generally 32 bits max (8 red, 8 green, 8 blue, and 8 alpha/transparency).