JavaScript particle simulator

[DanielRibeiro]

If you liked this, Chrome Experiments is filled with particle examples: http://www.chromeexperiments.com/search/results.html?q=parti...

Three.js also has some pretty nice to follow particles samples:

http://threejs.org/examples/#webgl_particles_random

http://threejs.org/examples/#webgl_particles_sprites

http://threejs.org/examples/#webgl_buffergeometry_particles

[theGimp]

The frame rate is incredible given the number of particles. JavaScript interpreters really have come a long way. The frame rate for JS particle simulation beats the frame rate you get when you tell a browser to append content, which is usually native C/C++ optimized to death.

To the author: great work. It looked very much alive on my screen when I first loaded the page.

[EpicEng]

JS is just the glue code. Try it out in raw JS and enjoy your .001 fps.

[ye]

It's not really JS, shaders are doing all the heavy lifting.

[arturventura]

Does anyone have the theoretical description of what is happening? I'm curious about the fractal patterns being generated and the increasing in entropy and the that results in a catastrophic failure of the stable system. Is this some kind of chaotic system or is just an force field being applied on the particules.

[Flexi23]

half a million particles are rendered to a texture, which is then blurred, and the gradients are used to update the velocity of the particles in a feedback loop. There's no direct interaction between individual particles. There are two words to describe the haphazard in the behavior. Use Google or Wikipedia to learn about "dissipative systems" and "stigmergy".

[technotony]

This is beautiful, after watching I feel like I finally understand how the universe developed structure after the big bang.

[clarkmoody]

I would love to see a choice of initial conditions, one of which being a couple 'galaxies' of particles on a collision course.

Also, a way to reset the simulation without reloading the page would be nice.

[ep103]

I moved the mouse very slightly at the edge, which caused all the particles to eventually settle in two separate spinning groups. Then I started making fast circles around one of the groups, and once the group started following the pattern, added a slowly moving center of rotation towards the other undisturbed group. This caused it to slowly move towards the stationary one, until they collided, each ripping from the other, until they merged.

[acadien]

Galaxies would require coupling of the particles, interactions through gravity... this would kill the efficiency of the solver. N-Particle simulations are always O(N^2) (or more).

[joshu]

The presentation this is from is at http://www.cake23.de/fmx/ - there's a lot more good stuff inside than just this.

[DanBC]

Y U NO SUPPORT OES_texture_float_linear?

Using Version 31.0.1650.57 m Google Chrome is up to date

[gilgoomesh]

It's not a friend of Safari 7 with WebGL enabled, either.

[d23]

I find this infinitely more interesting than the recent "X in 2.3 lines of JS" trend lately.

[girvo]

Oh come on, the ray tracer was really neat.

[iLoch]

So how long do I have to wait to see it go back to it's initial position? (Theoretically...)

[Flexi23]

I'm the original author of this little WebGL experiment and i want to try to answer some questions that came up here.

1) implementation there's quite some boilerplate in JS to set up all the textures and the main animation loop, but if you look closely the CPU is mostly idle and the "heavy lifting" is all done on the GPU by several shader programs. There are no libraries used and you can take a copy of the html file and simply start by breaking things apart. For the massive speed I'm updating the particle data with a clever fragment shader trick that i've learned from https://twitter.com/BlurSpline/status/161806273602519040 And in a DIY fashion, I've mashed this up with my own texture feedback loop. The main idea is that the particle positions (and the velocity vectors too, each 2D only) are stored in a texture's rgba values (float32). So updating the particles data is in fact a render process of a quad in one draw call. Then I had also rendered the particles to another texture to sum up the "density" of the primitive 1 pixel point projections.

2) complexity when it comes to the mere particle count, the complexity really is O(n), but there's a wee bit more to it. The projection of the particles to the framebufferobject or the screen is the most costly in this setup and it's fillrate-limited by the graphics card. There's a noticeable difference when the particles are evenly distributed or when they overlap, but it must stay in the O(n) realm i suppose. Then there's another texture feedback loop system that is also directly dependent on the pixel count. The particles are stored in a 1024x512 pixels wide texture and the hidden texture feedback layer is also of that size, but it could differ too. There is absolutely no direct interaction between any two particles here. I project the particles to a density texture that is then diffused with an optimized two-pass Gaussian blur calculation and several resolution reduction steps. All the textures from the different steps are available as in put sampler to the shader programs, in particular "fs-advance" for the Turing patterns and the density projection (hey there, the blue channel is unused ^^) and "fs-move-particles" where i simply grab the gradient from the diffused density to update the particle's velocity vector and do the verlet integration.

The concepts used here also have names - just ask google or wikipedia for "dissipative systems/structures" and "stigmergy".

3) the fluid simulation code is not by me! Evgeny Demidov is the original author of the WebGL shaders for that: http://www.ibiblio.org/e-notes/webgl/gpu/fluid.htm I'm only adding to the current advection matrix

4) code size this could possibly fit into a 4k demo but i have no interest in that kind of challenge. i rather like to share something that is easily readable by others.

cheers!

[pointernil]

This is really very impressive and thanks for sharing!

How many single particles are visible at every moment? Would it be possible to control the movement of the particles by the fluid field to form predefined shapes? to make them cluster into predefined (even moving) areas?

For some time now, i wonder if it would be possible to visualize some population statistics (think the percentile wealth distribution f.e. ;) by using some thing like this and make every single person "visible" within the statistic.

I believe it would make many "distributions" more intuitively understandable. Imagine some several thousand single "very wealthy" entities contrasted by several thousands or millions of "average" entities ;)

Obviously such interactive diagrams easily hit (hardware/software) limits, but even if displayed with some mapping like 1 point equals several (hundreds/thousands) real world entities, i think such display of magnitude in the real world would be very engaging.

Thanks again.

[darsham]

It's nice to see this up here, I've been a fan of your work since the milkdrop days. Is that when you started making shaders ? I gotta say MD2 was one of the best shader playgrounds i've ever used and it's how i was introduced to shader programming. You should do cinematic special effects :)

[pwnna]

How is this made?

It's pretty slow on my computer. Would ASM.js work better?

[fekberg]

I'm getting 15 FPS in Chrome on my Surface Pro.

It uses OpenGL ES it seems, doesn't work in IE 11.

Edit: It would be interesting to know if this would perform better using WebGL and running it in IE 11, anyone has any thoughts on that?

[mistercow]

It looks like most of the heavy lifting is done in shaders, so asm.js probably wouldn't improve it much.

[tumes]

Yes, but how many lines of javascript? It seems that's the metric above all metrics lately.

[spectre256]

but is it done in 30 lines of javascript? (i checked, no)

[vjoel]

Took me a long time to notice that my cursor movements were injecting disturbances into the fluid. What physical laws govern these points, and how is the cursor perturbing them?

[vjoel]

Also, why is there a bias towards clockwise orbits in the first few seconds? Is there some asymmetry in the physics?

[ffrryuu]

I don't think that's how particles work?

[mistercow]

Yeah, it's pretty, but I'd like to see some explanation of what exactly is being simulated here.

[crashandburn4]

is there anything detailing the maths/programming techniques behind this? can anyone confirm whether this is Barnes-Hut?

I've had a look here: http://creativejs.com/2013/11/coupled-turing-pattern-and-219...

but there's no details on the specifics

[Flexi23]

it's not Barnes-Hut, but good tip!

[stuartd]

Meh. U no support my 6 year old MacBook with crappy integrated graphics? Nothing on Safari 6.1, Firefox 25, Chrome 31..

[Bhel]

Cute, although not the best performance.

It'd be nice if the color gradually changed.

[lectric]

It looked fine to me, and the performance is a factor of your hardware. Get a faster computer.

[adcuz]

How do you even begin to write something like this?

[nni]

Maybe we're written in 30 lines of javascript, too. You can get - to us - surprisingly and beautiful complexity from simple rules.