I just wanted to point out my cool observation i had when watching the friday stream.
if you save to memory InverseAlpha:=(1-alpha) instead of alpha, you can get 2 things:
1. all of your alpha usage in the color section is done by InverseAlpha because of the premultiplied alpha, so it makes things nicer to read i think.
2. by following the mathematical derivetion casey did, the alpha section has the cool feature that (1-Abuffer)=(1-Asource)*(1-Adest),or:
InverseAlphaBuffer=InverseAlphaSource*InverseAlphaDest
and this is really nicer to see.
i know it does no good to try to optimize things now, but i think that it's cool enough to write on the forums.