10-10-2019, 10:19 PM
After going through other shaders and doing some experiments in Blender I think I have some partial answers:
- Interpolating from black to texture based on lighting is actually the same thing as interpolating from black to lighting based on texture. You shine a white light on a red thing and get red; you shine a red light on a white thing and get red. I don't understand the math behind it but the logic checks out. So basically, the b and c terms can be reversed to whatever makes more sense.
- Constant3_8 is probably "constant 3/8", or 0.375. There are other constants in the order Constant1_8, Constant1_4, Constant3_8, Constant1_2... it looks suspiciously like eighth fractions, and it goes up to Constant1_1.