I like the interactive processing canvas and penrose tiling is always cool. The interface / external html could use some more feedback about what is going on.

Site repo: https://github.com/etisab/etisab.github.io

Penrose repo: https://github.com/etisab/penrosetiler

Thanks for the feedback. What in particular did you find difficult or non-obvious about it?

Could anyone explain what's going on? (I.e. how my mouse position influences the shape?)

It's using Y position of the mouse to determine the size of the tiles.

http://etisab.github.io/penrose.js - see the processing.draw call.

This tiler uses an algorithm that recursively subdivides triangles according to certain rules. Moving the mouse lets you easily see each transformation from the previous. Try clicking anywhere on the page too.