This was the first thing I did when I wrote a fluid sim as well - I’ve spent a ton of time and energy pursuing ways to get subtractive color effects (the richness and light-subjectivity of pigment) in digital artifacts and have mostly come up empty, but I take every chance I can get.

Have you checked out mixbox[0]? The outputs do feel intuitively "right" as someone who has dabbled in watercolor, and the paper/videos cover the thinking and Kubelka-Munk theory well.

[0] https://github.com/scrtwpns/mixbox

Spectral.js might also be interesting. It comes with a GLSL implementation of Kubelka-Munk and is MIT.

https://github.com/rvanwijnen/spectral.js

Wild! Just saw that at the top of the front page and thought ‘dang is HN reading my mind today??’

Thanks for the link!

oh wow, they have the fluid demo too!!! Thats so much better!

https://scrtwpns.com/mixbox/fluids/

How difficult would it be to prevent the ink from disappearing? Any tips would be appreciated, I'd love to integrate this into a drawing app.

very easy, its a free parameter in the simulation see the "Ink dissipation" slider, you can set it to > 1 for some weird effects.

No such slider on mine. (https://i.imgur.com/m1tODYK.png)

you are looking at the wrong app https://observablehq.com/@tomlarkworthy/ink

Ah, thanks.

You could consider changing your ink to CMYK colors: `mutable ink = [255, 0, 255]`.