Shaders are where this comes into play and render to texture.

The screenshots have been taken down, but this had something to do with it:

http://www.conitecserver.com/ubbthreads/showflat.php?Cat=&Number=349748&page=0&view=collapsed&sb=5&o=21&fpart=1

My User Contributions master list - my initial post links are down but scroll down page to find list to active links