i'm just starting to get a grip on exposing HLSL properties to unity and then bringing those into the SubShader section for me to do the funny math with.

these introductory parts apply stuff about adding and multiplying colors which i'm already a little familiar with, but it pays special attention to what the common effects of those operations are: artistically, we should be thinking about what Additive does to dark parts and what Multiply does to light parts...

this connection between the shader math and the layer filters i've used in art programs for so long is growing a lot stronger in my mind. it wasn't so obvious to think about both together until i started reading this, honestly!