A lightweight JavaScript implementation of boids. Its "API" is a little limited, but it's reasonably performant - my MacBook ran the demo with 1,000 boids at 60 frames per second.
I used an earlier, hastier version for the flocks in grow.
For use with browserify:
npm install boidsvar boids = require('boids')
, raf = require('raf')
var flock = boids({
boids: 50, // The amount of boids to use
speedLimit: 0, // Max steps to take per tick
accelerationLimit: 1, // Max acceleration per tick
separationDistance: 60, // Radius at which boids avoid others
alignmentDistance: 180, // Radius at which boids align with others
choesionDistance: 180, // Radius at which boids approach others
separationForce: 0.15, // Speed to avoid at
alignmentForce: 0.25, // Speed to align with other boids
choesionForce: 0.1, // Speed to move towards other boids
attractors: []
})
raf(window).on('data', function() {
ctx.fillStyle = 'black'
ctx.fillRect(0, 0, canvas.width, canvas.height)
ctx.fillStyle = 'white'
ctx.save()
ctx.translate(-canvas.width/2, -canvas.height/2)
flock.tick()
flock.boids.forEach(function(boid) {
ctx.fillRect(boid[0], boid[1], 1, 1)
})
ctx.restore()
})flock = boids([options])
flock.tick()
Moves the boid simulation forward one tick - if you're running an animation, you should be calling this on each frame.
flock.boids
All of your boids are stored as an array of arrays, with each array containing the following variables for a single boid:
[xPosition, yPosition, xSpeed, ySpeed, xAcceleration, yAcceleration]Because the flock is just an array, it should be entirely safe for you to add and remove elements without any unintended side effects, provided all of the arrays are at least 6 elements long and contain numerical values. For example, you can add a new boid moving at a random speed to the origin like so:
flock.boids.push([0, 0, Math.random()*10-5, Math.random()*10-5, 0, 0])flock.attractors
You can use attractors to control the flow of the boids - essentially, providing them with goals and obstacles. Each attractor contains:
[xPosition, yPosition, radius, force]Note that you can use a negative value for force to repel boids instead of
attracting them. Again, it should be safe to modify, add and remove these
arrays without any surprises.
Running benchmark.js yielded the following results in Node:
50 boids: 34013 ticks/sec
100 boids: 10000 ticks/sec
150 boids: 4537 ticks/sec
200 boids: 2583 ticks/sec
250 boids: 1653 ticks/sec
300 boids: 1159 ticks/sec
350 boids: 835 ticks/sec
400 boids: 654 ticks/sec
450 boids: 518 ticks/sec
500 boids: 419 ticks/sec
550 boids: 347 ticks/sec
600 boids: 292 ticks/sec
650 boids: 249 ticks/sec
700 boids: 215 ticks/sec
750 boids: 187 ticks/sec
800 boids: 160 ticks/sec
850 boids: 130 ticks/sec
900 boids: 119 ticks/sec
950 boids: 107 ticks/sec
1000 boids: 95 ticks/sec
I'm very much open to pull requests that can help improve performance :)