/**
*
* Class Name  : ParticleEmitter
* Created     : 28/08/2012
* Require     : Three.js
*
**/

GAME_ENGINE.ParticleEmitter = function(scene, picture, psize, max) {
	this.scene = scene;
        this.psize = (psize) ? psize : 20;
	this.maxParticleCount = (max) ? max : 20;
	this.emitting = false;
	this.timer = 0;
	this.delay = 0; //60 fps -> 1 particle per second
	this.particleAnimation = null;
	this.particleInitializer = null;
        this.particles = [];
	this.Material = { color: 0xFFFFFF, size: psize, map: THREE.ImageUtils.loadTexture(picture), blending: THREE.AdditiveBlending, transparent: true };
	this.position = new THREE.Vector3(0, 0, 0);
}

GAME_ENGINE.ParticleEmitter.prototype.setParticleAnimation = function(animation) {
	this.particleAnimation = animation;
};

GAME_ENGINE.ParticleEmitter.prototype.setParticleInitializer = function(initializer) {
	this.particleInitializer = initializer;
};

GAME_ENGINE.ParticleEmitter.prototype.start = function() {
	this.emitting = true;
};

GAME_ENGINE.ParticleEmitter.prototype.stop = function() {
	this.emitting = false;
};

GAME_ENGINE.ParticleEmitter.prototype.destroyParticle = function (index) {
	this.scene.remove( this.particles[index] );
	this.particles.splice(index, 1);
}

GAME_ENGINE.ParticleEmitter.prototype.update = function( delta ) {
	if (this.emitting) {
		if (this.timer >= this.delay) {
			if(this.particles.length < this.maxParticleCount) {
				var particle = new THREE.Sprite( this.Material );
				particle.useScreenCoordinates = false;
				particle.mergeWith3D  = true;
				particle.affectedByDistance  = true;
				particle.scaleByViewport   = true;
				particle.position = new THREE.Vector3(this.position.x, this.position.y, this.position.z);
				particle.scale.x = particle.scale.y = this.psize;
				if (this.particleInitializer != null)
					this.particleInitializer(particle);
				this.particles.push( particle );
				this.scene.add( particle );
			}
			this.timer = 0;
		}
		this.timer += 1;
	}
	
	if (this.particleAnimation != null) {
		for (var i=0; i<this.particles.length; i++) {
			this.particleAnimation(this.particles[i], i);
		}
	}
};

// Usage :
// scene : THREE.Scene

var particlesEmitter = new GAME_ENGINE.ParticleEmitter(scene, "./textures/particles/01.png", 600, 35);

particlesEmitter.setParticleInitializer(function(particle){
        // Setup each particle at creation
	particle.initPos = this.position;
});
		
particlesEmitter.setParticleAnimation( function(particle, index) {
        // update each particle on loop
	particle.scale.x = particle.scale.y = 0.98*particle.scale.x;
	particle.opacity = 0.90*particle.opacity;
        particle.position.y += 1;
	if (particle.position > 100)
		this.destroyParticle(index);
});
		
particlesEmitter.start();