Show HN: HTML5 Bird Flocks Simulation in CoffeeScript

http://chrisp.gr/projects/boids/

by chris_p • 14 years ago

47 25 14 years ago

chrisp.gr

MatthewPhillips• 14 years ago

Link the github page 404s.

chris_p6• 14 years ago

Thanks, I fixed it!

Malcx2• 14 years ago

Smooth running, but the flocking behaviour just doesn't quite feel right. The boids overlap/collide and just don't feel to "flock" correctly.

Do they have awareness of the other boids around them?

chris_p6• 14 years ago

Yes, they do. They're not meant to completely avoid each other, theoretically there's a Z-axis that's not visible.

Try increasing the collision avoidance importance in the options and decreasing everything else. Generally, playing with the sliders can result in completely different behaviors.

Malcx2• 14 years ago

Ah OK - yes some better behaviour can be adjusted, maybe tweak the default values a bit?

jameshart• 14 years ago

The attraction to the center seems to produce very erratic pathing - cutting that to zero immediately makes the flocking effect more 'natural'. Then increasing the acceleration factor helps produce those instantaneous changes of direction that are characteristic of animal flocks. With the current defaults the behavior is more 'cloud of flies' than 'flock of starlings' - which is fine, but doesn't show off the large scale co-ordinated movement the boids algorithm can produce. The collision avoidance threshold seems a little high - a slider to reduce that would help make flocks more compact which would produce better behavior when the number of boids is high...

kushsolitary• 14 years ago

This is what I did a few months ago http://cssdeck.com/labs/ckosol2k/1

But yours feel much better.

Edmond2• 14 years ago

Please hack for education!

Here's my last appeal:

http://news.ycombinator.com/item?id=4534204

onehp2• 14 years ago

I really like yours, the direction changes and merging are a bit 'robotic' but I like the cohesion.

amirrajan• 14 years ago

Any similarities to the bird flocking algorithm when compared to a force directed graph? Here's a link to a force directed graph I did in HTML5: http://amirrajan.net/Home/FdgHtml5

chris_p6• 14 years ago

Bird flocks are actually much simpler. It's just three simple rules that define how each boid moves.

Edmond2• 14 years ago

Love it...Please hack for education!

Here's my last appeal:

http://news.ycombinator.com/item?id=4534204

onehp2• 14 years ago

I had a go at this too a little while ago.

It's not web based unfortunately so here's a short video of it running: http://www.youtube.com/watch?v=eY4DHcsuv1Y&feature=youtu...

And sourcecode: https://github.com/OneHP/murmuration

Also because I'm not great with my vector maths you'll spot that the boids have some odd behaviour where they favour vertical movement. Strange little bug.

iamwil• 14 years ago

Like others here, I had a run at this using lua love four years back.

https://github.com/iamwilhelm/frock

In my experience tweaking the variables, to make it look 'realistic', the settings need to change as the number of boids increase. So what might work for n boid, won't work for m boids, where m >> n.

In addition, you need to limit the turn angle for the boids. They don't look like they're flocking as much as they're orbiting. Just as birds can't turn on a dime (actually, they can. I've seen a sparrow change direction in mid-flight just as I was going to hit it with my car going 40 mph, but for the purpose of flocking it looks better when they can't.), you don't want your boids to, so you get a swooping effect and feel.

eyevariety• 14 years ago

Sage advice. It took me longer than it should have to learn this.

andrewfhart• 14 years ago

nice!

Another great take on an HTML5 flocking implementation is Alex Cruikshank's "birds on a line" demo, in which the birds also "land" on wires. I really like how Alex handles 3-dimensionality by adjusting the darkness of the birds so that the further "back" they are, the lighter they appear.

demo: http://carbonfive.github.com/html5-playground/birds-on-a-lin... source: https://github.com/acruikshank/html5-playground/blob/gh-page...

SeanDav• 14 years ago

Just had a look at this one - definitely one of the better flocking/swarming implementations I have seen.

Lockyy2• 14 years ago

My immediate reaction is that I really want this as a screensaver.

Absolutely beautiful. I will definitely take a crack at making the screensaver myself when I get around it it.

chris_p6• 14 years ago

Thank you! Do you think there's any way to not rewrite the entire thing?

Lockyy2• 14 years ago

I have absolutely no idea, I don't know a thing about making screensavers, but I'm willing to learn if I can set this up as one.

shuw• 14 years ago

I also use flocking algorithm for a visualization of words on my homepage http://shuw.github.com/. I ported the algorithm to D3 here https://github.com/shuw/flock if anyone wants to reuse it

hythloday2• 14 years ago

This is very attractive. What's the "flock size" slider? Is it the number of neighbours it keeps track of or the neighbour distance?

chris_p6• 14 years ago

It's the number of neighbors each boid considers to calculate its velocity. There's also an option that defines the maximum distance for collision detection, but it's not accessible through the UI.

hythloday2• 14 years ago

Thanks! The canonical data structure to avoid the O(n^2) lookup is a kdtree, which I think is reasonably easy to implement in coffeescript.

Show HN: HTML5 Bird Flocks Simulation in CoffeeScript

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