Simple "Shake" plugin for Phaser 1.1.3 with postUpdate

Shake.js

/* Simple "Shake" plugin */

/* Use it like: */
var shake = new Phaser.Plugin.Shake(game);
game.plugins.add(shake);

shake.shake(40); // 40 pixels max displacement


/*
Plugin implementation 
*/
Phaser.Plugin.Shake = function(game, parent) {
    Phaser.Plugin.call(this, game, parent);

    this.offsetX = 0;
    this.offsetY = 0;

    this.size = 20;
    this.amt = 0.0;

    this.cache = 0;
};

Phaser.Plugin.Shake.prototype = Object.create(Phaser.Plugin.prototype);

Phaser.Plugin.Shake.prototype.postUpdate = function () {

    this.cache = this.amt * this.size;

    this.offsetX = ((Math.random() * 2 - 1) * this.cache)|0;
    this.offsetY = ((Math.random() * 2 - 1) * this.cache)|0;

    this.game.camera.displayObject.position.x += this.offsetX;
    this.game.camera.displayObject.position.y += this.offsetY;

    this.amt *= 0.95; // Todo: framerate independence!
    
};

Phaser.Plugin.Shake.prototype.postRender = function() {
    this.game.camera.displayObject.position.x -= this.offsetX;
    this.game.camera.displayObject.position.y -= this.offsetY;
}

Phaser.Plugin.Shake.prototype.shake = function (size) {

    if(typeof(size) !== 'undefined') {
        this.size = size;
    }

    this.amt = 1.0;
};