Combining pixels with arithmetic & logical operators

I’m interested in 2D work.

Quickdraw’s got a lot of esoteric penmodes that allow you to combine two pixels’ RGB values using a variety of arithmetic and logical operators (OR,AND,ADD,etc.). The only close equivalent I’ve been able to find in the OpenGL environment is for blending and transparency. Have I missed something? Is there any way of patching a primitive somewhere in OpenGL to add this capability?

Please reply via email to

Do not forget the accumulation buffer. You can do some pixels operations using that. But not many.