boids/demo.js

ERROR: No README.md file found!

var fps = require('fps')
  , ticker = require('ticker')
  , debounce = require('debounce')
  , Boids = require('./')

var attractors = [[
    Infinity // x
  , Infinity // y
  , 150 // dist
  , 0.25 // spd
]]

var canvas = document.createElement('canvas')
  , ctx = canvas.getContext('2d')
  , boids = Boids({
      boids: 150
    , speedLimit: 2
    , accelerationLimit: 0.5
    , attractors: attractors
  })

document.body.onmousemove = function(e) {
  var halfHeight = canvas.height/2
    , halfWidth = canvas.width/2

  attractors[0][0] = e.x - halfWidth
  attractors[0][1] = e.y - halfHeight
}

window.onresize = debounce(function() {
  canvas.width = window.innerWidth
  canvas.height = window.innerHeight
}, 100)
window.onresize()

document.body.style.margin = '0'
document.body.style.padding = '0'
document.body.appendChild(canvas)

ticker(window, 60).on('tick', function() {
  frames.tick()
  boids.tick()
}).on('draw', function() {
  var boidData = boids.boids
    , halfHeight = canvas.height/2
    , halfWidth = canvas.width/2

  ctx.fillStyle = 'rgba(255,241,235,0.25)' // '#FFF1EB'
  ctx.fillRect(0, 0, canvas.width, canvas.height)

  ctx.fillStyle = '#543D5E'
  for (var i = 0, l = boidData.length, x, y; i < l; i += 1) {
    x = boidData[i][0]; y = boidData[i][1]
    // wrap around the screen
    boidData[i][0] = x > halfWidth ? -halfWidth : -x > halfWidth ? halfWidth : x
    boidData[i][1] = y > halfHeight ? -halfHeight : -y > halfHeight ? halfHeight : y
    ctx.fillRect(x + halfWidth, y + halfHeight, 2, 2)
  }
})

var frameText = document.querySelector('[data-fps]')
var countText = document.querySelector('[data-count]')
var frames = fps({ every: 10, decay: 0.04 }).on('data', function(rate) {
  for (var i = 0; i < 3; i += 1) {
    if (rate <= 56 && boids.boids.length > 10) boids.boids.pop()
    if (rate >= 60 && boids.boids.length < 500) boids.boids.push([0,0,Math.random()*6-3,Math.random()*6-3,0,0])
  }
  frameText.innerHTML = String(Math.round(rate))
  countText.innerHTML = String(boids.boids.length)
})