It was made using Haskell. Actually, I'll list below how the animation evolved. Long story short, I decided in the final variants to cast the RGB cube surface on the big square, then animating it.

* https://gfycat.com/InsidiousPresentGoa

* https://gfycat.com/SpiffyFaithfulBanteng

* https://gfycat.com/PracticalFatKentrosaurus

* https://gfycat.com/CheapMisguidedBufflehead

* https://gfycat.com/InsidiousSphericalAzurewingedmagpie

* https://gfycat.com/HollowGlaringGraywolf

* https://gfycat.com/WillingBothGoose

* https://gfycat.com/PerfumedMediocreAndeancat

* https://gfycat.com/GeneralHandyLeonberger