Nice examples, I think I landed on that page quite a while ago. I love Processing and Perlin noise. One thing I enjoyed was using Perlin noise values to compute a "region" on the canvas and making the behavior of a particle depend on which region it was in. Examples:

https://020406.org/processing/PerlinNoiseBounds1.png

https://020406.org/processing/PerlinNoiseBounds2.png

https://020406.org/processing/PerlinNoiseBounds3.png

The Processing code I wrote to make them is here: https://github.com/Brian-Fearn/Processing/blob/main/PerlinNo...