This example is not interactive. Of course it doesn't need state, it is essentially playback of an animation. John Carmack once pointed out, procedural generat

This example is not interactive. Of course it doesn't need state, it is essentially playback of an animation. John Carmack once pointed out, procedural generation is essentially just compression. Video playback only has time as state too. This is just pointing out that if you have data to play back, all you need is a time variable for state. If you want to make that data procedurally (or somewhere in between by embedding a curve) you can do that too. This does not have anything to do with programming in general.