Screenshake plugin for PhaserJS

Screenshake.plugin.js

function Screenshake (game, parent) {
  Phaser.Plugin.call(this, game, parent);
  
  this.timer = this.game.time.create(false);
  this.timer.start();
  
  this.shakeCount = 0;
  this.shakeAmount = 1;
  
  this._initialBounds = this.game.camera.bounds;
  this.game.camera.bounds = null;
  
  this._cameraPosCache = [this.game.camera.x, this.game.camera.y];
}

Screenshake.prototype = Object.create(Phaser.Plugin.prototype);
Screenshake.prototype.constructor = Screenshake;

Screenshake.prototype.update = function () {
  if (this.shakeCount > 0) {
    var t = 2 * Math.PI * this.game.rnd.frac();
    var u = this.game.rnd.frac() + this.game.rnd.frac();
    var r = (u > 1 ? 2 - u : u) * this.shakeAmount;
    
    this.game.camera.x = r * Math.cos(t);
    this.game.camera.y = r * Math.sin(t);
  }
};

Screenshake.prototype.shake = function (duration, amount) {
  if (this.shakeCount === 0) {
    this._cameraPosCache[0] = this.game.camera.x;
    this._cameraPosCache[1] = this.game.camera.y;
  }
  
  this.shakeCount++;
  this.shakeAmount = amount || 1;
  this.timer.add(duration || 100, this.shakedown, this);
};

Screenshake.prototype.shakedown = function () {
  this.shakeCount--;
  
  if (this.shakeCount === 0) {
    this.game.camera.setPosition(this._cameraPosCache[0], this._cameraPosCache[1]);
  }
};

Phaser.Plugin.Screenshake = Screenshake;