A 2D Physics Simulator in JavaScript
Learning and science
physics simulation
SHOW HN2017
126points
62comments
#333of 2,242 in 2017
Top 15%of 2017 by points
How HN took it
DebatedReal support and real criticism
6 positive, 5 neutral or asking, 1 mixed, 11 critical, out of 23 comments about the project. Thread score -0.26.
Idea: 1 for, 5 againstPerformance: 1 for, 5 againstDocs: 2 for, 0 againstExecution: 0 for, 1 against
The thread, comment by comment
Each row is a top-level comment and its replies, in HN's order. Select a cell to open that comment on HN.
positive neutral or mixed critical about another commenter or something else the maker
What HN said
What people liked
Code fits on one page and is easy to understand
From 1 comment
What's special about this simulation is that the entire code fits on one page, including linear algebra library:…
ivan_ah on HN
Good for learning and teaching physics simulation
From 2 comments
What's special about this simulation is that the entire code fits on one page, including linear algebra library:…
ivan_ah on HNThanks, good show. Another one I like is http://physics.weber.edu/schroeder/html5/. See Newton's cannon etc.
pdm55 on HN
Objections
No friction, so motion looks unrealistic
From 3 comments
In Firefox Developer Edition everything happens faster than in regular Firefox, though they seem to end at the same result. I wonder why that is. Animation doesn't seem much…
SketchySeaBeast on HNThe only part missing? Physics... Somehow boxes slide along a flat floor with no deceleration until they fall off the screen
dmitrygr on HNI think the word you were looking for was "friction". This certainly looks like a simulation that a physics professor would propose on a chalk board: "Ignoring friction for the…
eric_h on HN
Not interactive; cannot modify objects
From 2 comments
Is this really a simulation if you can't modify any of the objects? For all we know, this could all be pre-calculated or pre-animated. Everything moves exactly the same way every…
dkonofalski on HNErm, no offense but: a) physics programs are supposed to offer interactivity. Else whats the point? b) the physics look unearthly
laythea on HN
Non-deterministic or varies across browsers
From 2 comments
It moves differently in different browsers for me. And neither instance seems to actually make physical sense. In Chrome, the fourth box from the top starts sliding when it hits…
FroshKiller on HNI don't mean to be rude, but if you don't know the term I'd put money on it not being deterministic. Especially if you're running in JavaScript on multiple browsers. A single…
reificator on HN
High CPU usage due to no broad phase collision detection
From 2 comments
Out of curiosity: The chrome tab running the engine is using 55% of my CPU, an i7-4770K running at 3.5Ghz... Box2D with many more objects consumes 22%. Oimo, with a 3D rendering…
danilocesar on HNPhysics engines are like magic and it is pretty hard understand how the work even if you read the paper many times. Also physics engines are interesting not only because four the…
xchip on HN
Requests
Add friction
From 3 comments
Is there friction or non-zero restitution?
santaclaus on HNIt doesn't take into account surface friction? Those boxes seem covered in soap to me.
Aeolun on HNIn Firefox Developer Edition everything happens faster than in regular Firefox, though they seem to end at the same result. I wonder why that is. Animation doesn't seem much…
SketchySeaBeast on HN
Add user interaction such as mouse control
From 2 comments
:D you are welcome to add objects, make the chain longer or change gravity... Having always the same animation helps debugging. But yeah I should have added the option to add a…
xchip on HNHey, again no offense meant. I just think the whole point of something like this is to mimic the real world. And after a couple of seconds my illusion is broken. Ps. It is cool,…
laythea on HN
Questions
Is the simulation deterministic?
From 1 comment
Cool! Is it deterministic? Does it do destructive updates?
mobiletelephone on HN
Does it conserve energy?
From 1 comment
This is where I show that I know nothing about physics engines: ... does it have conservation of energy? Can you track total energy somehow? ... does it obey approximately some…
thanatropism on HN
Alternatives named
Matter.js
From 2 comments
Why is this upvoted so much? In what way is it better than any of the existing JS physics engines? Matter.js: http://brm.io/matter-js/ Cannon.js: http://www.cannonjs.org/…
olegkikin on HNIf you want to look at precedence or what other people have done successfully in this space check out http://brm.io/matter-js/ matter JS. It's pretty sweet.
ell0ell0 on HN
Box2D
From 2 comments
Why is this upvoted so much? In what way is it better than any of the existing JS physics engines? Matter.js: http://brm.io/matter-js/ Cannon.js: http://www.cannonjs.org/…
olegkikin on HNOut of curiosity: The chrome tab running the engine is using 55% of my CPU, an i7-4770K running at 3.5Ghz... Box2D with many more objects consumes 22%. Oimo, with a 3D rendering…
danilocesar on HN
Cannon.js
From 1 comment
Why is this upvoted so much? In what way is it better than any of the existing JS physics engines? Matter.js: http://brm.io/matter-js/ Cannon.js: http://www.cannonjs.org/…
olegkikin on HN
PhysicsJS
From 1 comment
Why is this upvoted so much? In what way is it better than any of the existing JS physics engines? Matter.js: http://brm.io/matter-js/ Cannon.js: http://www.cannonjs.org/…
olegkikin on HN
myphysicslab
From 1 comment
To add to the list, the best physics engine I've seen (not for js games, for actual physics simulations to teach people physics) is this one: https://www.myphysicslab.com/ PheT…
ivan_ah on HN