This one continues the theme of “little dots that do things”. In this case it’s “simulate various materials and their interactions, in a literal sandbox.”
There’s very little that’s novel about this, there are dozens of simulators just like this one already online, but it was fun to think of new interactions for the various materials, and figuring out how to simulate turbulence was an interesting challenge. (I Navier’d. I even Stokes’d. Then I decided that was too slow and switched to a simple diffusion field with decay, which looks pretty ok.)
