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    boidspublic

    boids

    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.

    check out the demo

    I used an earlier, hastier version for the flocks in grow.

    Installation

    For use with browserify:

    npm install boids

    Usage

    var 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.

    Benchmark

    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 :)

    install

    npm i boids

    Downloadslast 7 days

    6

    version

    2.0.0

    license

    MIT

    repository

    github.com

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