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Matter.js – A 2D rigid body physics engine for the web

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Re: Matter.js – A 2D rigid body physics engine for the web

#22

Post by tlarkworthy »

TheSisb2 wrote: post #16
dyarosla wrote: post #5

Pros: The samples play well, look fun, and it looks like a great solution to small physics demos in JS. Great job! Cons: Playing with the Stress demos (especially #2) really shows the slowdowns and downsides to using a JS based engine. At 450 boxes (+ 4 bounding walls), it runs at 20fps on my Macbook and thats with a lot of jitter and overlap. Not as fun. Edit: Significantly better w/ WebGL render, @32fps, and with s…

Have you seen PixiJS? http://www.pixijs.com/ It's used by PhaserJS, a very promising JS Game Framework

Pixi is the rendering engine used by Phaser. More relevant is the different physics engine Phaser supports (Box2D, P2 and its own lightweight arcade physics engine). Also Phaser is Typescript but distributed as JS. You can link it directly with Typescript too though which is why I like it a lot.

Re: Matter.js – A 2D rigid body physics engine for the web

#25

Post by hamburglar »

There are some bugs with "enable sleeping" turned on. Occasionally an object that is sleeping seems to fail to have external forces act upon it. For example, you can end up with a sleeping object sitting on top of another object, and when the object falls out from under it, the sleeping object stays stuck in midair. I can reliably make this happen by toggling "enable sleeping" on and off (example: load up "wrecking ball", stop the wrecking ball before it hits the pile, turn on "enable sleeping", wait for all the blocks in the pile to go to sleep, then turn "enable sleeping" back off and you now have a stack of immovable blocks which the wrecking ball bounces off of, and which will hover if you remove the bricks below them), but I saw the bug occur even when I wasn't flipping this setting back and forth.

Re: Matter.js – A 2D rigid body physics engine for the web

#26

Post by hngiszmo »

demo request:

I want a demo where the user can control a soft body ball such that the ball is comprised of chain segments, connected with string constant k. The pressure of the ball would be calculated depending on the area enclosed by the chain's polygon and would be applied to each segment equally, to the outwards side. Controls would be left/right as a simple added force to all segments of the ball. Jump would be increased air amount (target surface area) and crouch would be decreased k. In my imagination, the ball would be low friction and would grow throughout the game, to take on bigger adversaries.

(Sharing it here cause I didn't get to code it in years but I would really love to see if the control would work.)

Re: Matter.js – A 2D rigid body physics engine for the web

#28

Post by maccard »

dyarosla wrote: post #18
jsheard wrote: post #8

Earlier quoted context omitted.

GPU acceleration isn't going to be practical until >WebGL2, when we get access to compute shaders. You can technically do compute now by expressing your data as textures and performing rendering passes over it, but trying to do anything non-trivial that way will quickly lead to madness.

I mean, this is what I'm looking for. Sure it would be madness, but if you have 450 bodies represented by, say, 10 floats each (random number), that comes to about 4500 pixels of values- something a GPU is fine at.

in 3d you normally represent by a 4x4 matrix, which can be easily reduced to 6 floats (x y z translation, and x y z rotations). The problem with doing that little work is you'll very quickly be bottlenecked by copying memory to/from the GPU. If you want to do any raycasts for instance, or query for occlusion/bounds testing, you need to upload data to the GPU, run a (potentialy very slow, serial) query, then copy the result back. The results normally aren't worth it.

Re: Matter.js – A 2D rigid body physics engine for the web

#29

Post by maccard »

hamburglar wrote: post #25

There are some bugs with "enable sleeping" turned on. Occasionally an object that is sleeping seems to fail to have external forces act upon it. For example, you can end up with a sleeping object sitting on top of another object, and when the object falls out from under it, the sleeping object stays stuck in midair. I can reliably make this happen by toggling "enable sleeping" on and off (example: load up "wrecking b…

Enabling sleeping is a difficult thing to actually do, especially in a stack of bodies. You have to enforce a minimum movement threshold over a series of frames usually, and group bodies together to go to sleep, and also wake the same group up when there's motion. It's not always easy to do

Re: Matter.js – A 2D rigid body physics engine for the web

#30

Post by chromakode »

hngiszmo wrote: post #26

demo request: I want a demo where the user can control a soft body ball such that the ball is comprised of chain segments, connected with string constant k. The pressure of the ball would be calculated depending on the area enclosed by the chain's polygon and would be applied to each segment equally, to the outwards side. Controls would be left/right as a simple added force to all segments of the ball. Jump would be…

Sounds like Gish! http://www.chroniclogic.com/gish.htm
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