so p5art was having trouble replicating this gif by beesandbombs, or, rather looping it properly.
and I spend quite some time trying to figure it out. here is my code modified from p5art’s.
basically, the “size rotation takes happening while whole thing rotates by number of degrees equal to angle between two circles. the trick is to account for that angle.
that was fun! helped to shake some rust from my brain. getting back to making stuff.