Collaborative painting on a shared canvas with p5.js and node.js.
As seen on The Coding Train by Dan Shiffman. Video: https://youtu.be/i6eP1Lw4gZk from 13 Apr 2016. Code: https://github.com/CodingTrain/website/tree/master/Node/sockets
Extras: scaling, colour picker, pen size, clear, save. TODO: group parts of the drawing by ClientID, selectively clear.