This is a bit of an old topic now, but I came across a file I made a couple years ago to create the reaction diffusion effect such as was demonstrated here:
entagma.com/houdini-true-3d- … diffusion/
In any case, I’ve cleaned up my file and attached it here if anyone wants to take a look. And there’s a demo of it working here:
vimeo.com/275773035
Diffusion.toe (20.2 KB)