I did some, what amounts to, pigment-level color mixing, with RGB and CYM “pigments”
Everything within the triangle has individual pigment levels between 0 and 1. All three together always sum to 1. Outside, stuff will no longer make sense, as it may involve negative amounts of at least one of the base colors, making things go out of gamut.
You’re looking at a diffuse plane lit by a uniform white background.
I also provided the exrs in case they are of any use what so ever.
RGB:
https://www.dropbox.com/s/86i1bw7d8qooft3/rgb%20color%20mixing.exr?dl=0
CYM:
https://www.dropbox.com/s/k7umjimmyowwtsf/cmy%20color%20mixing.exr?dl=0
The material looks like this:
And the “Triangle Basis” node does this:
