index.js

var MersenneTwister = require('mersenne-twister');
var paperGen = require('./paper')
var Color = require('color')
var colors = require('./colors')
var shapeCount = 4
var svgns = 'http://www.w3.org/2000/svg'

module.exports = generateIdenticon

var generator
function generateIdenticon(diameter, seed) {
  generator = new MersenneTwister(seed);
  var remainingColors = hueShift(colors.slice(), generator)

  var elements = paperGen(diameter, genColor(remainingColors))
  var container = elements.container

  var svg = document.createElementNS(svgns, 'svg')
  svg.setAttributeNS(null, 'x', '0')
  svg.setAttributeNS(null, 'y', '0')
  svg.setAttributeNS(null, 'width', diameter)
  svg.setAttributeNS(null, 'height', diameter)

  container.appendChild(svg)

  for(var i = 0; i < shapeCount - 1; i++) {
    genShape(remainingColors, diameter, i, shapeCount - 1, svg)
  }

  return container
}

function genShape(remainingColors, diameter, i, total, svg) {
  var center = diameter / 2

  var shape = document.createElementNS(svgns, 'rect')
  shape.setAttributeNS(null, 'x', '0')
  shape.setAttributeNS(null, 'y', '0')
  shape.setAttributeNS(null, 'width', diameter)
  shape.setAttributeNS(null, 'height', diameter)

  var firstRot = generator.random()
  var angle = Math.PI * 2 * firstRot
  var velocity = diameter / total * generator.random() + (i * diameter / total)

  var tx = (Math.cos(angle) * velocity)
  var ty = (Math.sin(angle) * velocity)

  var translate = 'translate(' + tx + ' ' +  ty + ')'

  // Third random is a shape rotation on top of all of that.
  var secondRot = generator.random()
  var rot = (firstRot * 360) + secondRot * 180
  var rotate = 'rotate(' + rot.toFixed(1) + ' ' + center + ' ' + center + ')'
  var transform = translate + ' ' + rotate
  shape.setAttributeNS(null, 'transform', transform)
  var fill = genColor(remainingColors)
  shape.setAttributeNS(null, 'fill', fill)

  svg.appendChild(shape)
}

function genColor(colors) {
  var rand = generator.random()
  var idx = Math.floor(colors.length * generator.random())
  var color = colors.splice(idx,1)[0]
  return color
}

var wobble = 30
function hueShift(colors, generator) {
  var amount = (generator.random() * 30) - (wobble / 2)
  return colors.map(function(hex) {
    var color = Color(hex)
    color.rotate(amount)
    return color.hexString()
  })
}