Tear the cloth with your mouse.
Right click and drag to cut the cloth.
Reduce physics_accuracy if it's laggy, increase it for a better effect.
~2014 from http://codepen.io/stuffit/pen/KrAwx
seems to be original source: http://gamedevelopment.tutsplus.com/tutorials/simulate-fabric-and-ragdolls-with-simple-verlet-integration--gamedev-519
https://www.reddit.com/r/gamedev/comments/1b404w/tearable_cloth_in_javascript/