from Hacker News

PhysicsJS Examples: Newton's Revenge

by 6ren on 10/30/13, 5:16 AM with 15 comments

• by chengsun on 10/30/13, 3:29 PM

  Some of the examples (the cloth and the tree) seem to be based off Sub Protocol's verlet-js demonstration [1], which were on Hacker News a while back (HN discussion [2]). There was a similar issue with angular momentum not being conserved on those examples too.

  [1] http://subprotocol.com/verlet-js/

  [2] https://news.ycombinator.com/item?id=5580596

• by jbri on 10/30/13, 7:10 AM

  Something seems off about the simulation - once you get a big clump, it starts spinning faster and faster until it tears itself apart again.

  Ignoring that, it's pretty neat - and runs decently fast as well.

• by jheriko on 10/30/13, 1:44 PM

  small niggle. what is a verlet constraint? (rhetorical)

  whilst its obvious that you have just discovered verlet integration and the relaxation method of applying constraints - because everyone goes off and writes a physics engine at this point - i only think i know what you mean because i have assumed this.

  are these length constraints, angle constraints etc?

  still... no matter how common and unexciting this is for me, its always cool to play with physics simulations for five minutes. thanks for sharing. :)

• by joshvm on 10/30/13, 12:53 PM

  The tearable cloth demo is impressive!

• by toblender on 10/30/13, 6:53 PM

  My favorite one was "Supermarket catastrophe".

  Been wondering about where I can get a physics engine to simulate wind. I want to create a wind turbine simulator.

• by bsenftner on 10/30/13, 2:50 PM

  I had to run in Chrome, as FireFox reported 10 FSP while actually displaying less than 1 fps. Nice.

• by nickthemagicman on 10/30/13, 12:55 PM

  This is really cool.

  I'd like a 3d version to combine with three.js.

• by est on 10/30/13, 7:28 AM

  drag "Fruitcake on wheels" like crazy -> get messed up

• by pit on 10/30/13, 1:19 PM

  You can really torture those poor trees...