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PhysicsJS Examples: Newton's Revenge
- jbri 13y agoSomething 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.
- beloch 13y agoI noticed that angular momentum seems to be an unconserved quantity as well. I would not want to be an astronaut in the universe simulated here!
- raverbashing 13y agoYeah, this is almost a planetary cloud coming together. But I suppose the collisions are (too) elastic, also there's the issue with the spinning. But still you can see several concepts in action, and sometimes you get a big planet with a moon orbiting it.
- drakeandrews 13y agoThis is because each "atom" is of a considerable size to the larger clumps and imparts its excess momentum as angular momentum when it joins a clump. "Atoms" that are rotating around a clump in the opposite direction tend to skip off, and thus don't join and slow the rotation. I think.
- jbri 13y agoNo, that's not it. If you restart the simulation a few times, you should eventually get something where everything forms into one clump with low initial angular momentum. If you keep watching from that point, you'll see the clump's rotation accelerate entirely on its own. I'm not entirely sure on the cause, but it does seem to be a simulation flaw.
- drakeandrews 13y agoYou're right. At a guess, as collisions appear to be perfectly elastic particles inside a clump are trying to move and instead of their shifting being dampened, it's causing the whole structure to begin to rotate which causes more in-clump collisions causing... until it spins apart. Sound reasonable?
- est 13y agodrag "Fruitcake on wheels" like crazy -> get messed up
- japhyr 13y agoIt took me a while to realize I could play with the objects. It got even more interesting once I realized I could do that.
- joshvm 13y agoThe tearable cloth demo is impressive!
- nickthemagicman 13y agoThis is really cool. I'd like a 3d version to combine with three.js.
- pit 13y agoYou can really torture those poor trees...
- jheriko 13y agosmall 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. :)
- bsenftner 13y agoI had to run in Chrome, as FireFox reported 10 FSP while actually displaying less than 1 fps. Nice.
- chengsun 13y agoSome 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/ http://subprotocol.com/verlet-js/ [2] https://news.ycombinator.com/item?id=5580596 https://news.ycombinator.com/item?id=5580596
- toblender 13y agoMy 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.