I posted something similar enquiring about other blend modes but can't find it now.
I was looking at the old AmigaBlitz and found modes like AND, OR, XOR, INVERT. Not sure what OpenGL has to offer with regards to such render modes though.
I was looking at the old AmigaBlitz and found modes like AND, OR, XOR, INVERT. Not sure what OpenGL has to offer with regards to such render modes though.