This is a Poincaré map of the standard map. \(p_{n+1} = p_n + K\sin(\theta_n)\) and \(\theta_{n+1} = \theta_n + p_{n+1}\).
You can find this sketch on the p5.js website as well to play around with it.
Double click (tap) to reset the the map with a new (random) parameter \(K \in (0,4)\).