Dissolve the World with Slime Magic

This is a post about some animations I made, such as these:

• The algorithm is simple; this diagram, discussed further here, is pretty much the whole thing. The simulation relies on a large number (~5 million) particles following the given rules. It’s inspired by a computational model for the process that some slime molds (Physarum polycephalum) use to explore space.

• The magic is the programming language we use for implementing it, Futhark. Futhark allows you to write ML/Haskell style programs that are highly optimized for GPU execution. It comes with a great blog, surprisingly good documentation, and an attentive maintainer.

• My code is here (it’s all rather hacked together). Run pip install -r requirements.txt and follow the Futhark installation instructions. Then run make slime2.py and run using python run.py (you’ll need to modify this script to choose an image). My laptop GPU is able to render in the ballpark of a few million particles and one million pixels at real time.

• I have a few ideas for extension:

  • Add more control over brightness and color (the normalization done does not look great).
  • Implement a proper “food” resource that initially attracts slime but fades over time. It should probably have a higher attractiveness coefficient than signal.
  • Implement different species of slime; for instance, each color channel might repulse the others.
  • Make the simulation more physically realistic; for instance, implement a basic fluid simulation to simulate advection
  • Try driving the simulation with a video instead of an image. I’m not sure how this would work, but maybe the simulation would run for a fixed number of steps per frame, using the next frame as a source of attraction

  Dear reader, if you make anything inspired by this code, I’d love to see it 😁.

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