I'm a little confused, and I'm having trouble googling my troubles away. I'm getting into some of OpenGLs blendy abilities, so glBlendFunc has become of interest to me.
There is no shortage of the manual out there, but I don't quite get something.
I think what I'm not understanding is what color scaling is all about. At least, why there would be two of them. In my brain, I see blending as having a function that takes the new and the old colors, does stuff to them, returns the output color. Functions are like 'add', 'screen', etc... Yet, glBlendFunc asks for two parameters, and I can't seem to understand it.
Could somebody please explain to me (or maybe link to something with a good explanation) glBlendFunc's two parameters and how they affect the blending?