I love Eschers works. A few years ago I watched an documentary about his in the cinema, but I can remember the name.

3Blue1Brown just released an amazing video explaining the geometric transformation for Eschers print gallery. This made me try to reimplement the effect as WebGL shader [1].

It was very much fun especially doing it fully on my own just based on the general idea without looking at actual existing implementations. It highlighted for me how in non-linear transformations even small mistakes on my side can have huge negative effects on the final image that are tricky to pin down due to the non-linearity.

[1]: https://static.laszlokorte.de/escher/