eenScale	= (function(){
		var tweenMidi	= createTweenMidi(maxAge, 0.2*maxAge, 0.2*maxAge);
		return function(age){
			return (1 + 1 * tweenMidi(age)) * 0.2
		}
	})();
	var lastEmit	= 0;
	var prevPosition= new THREE.Vector3().copy(position);
	loop.hook(function(delta, now){
		// rate limiter emittion
		var rate = 70;
		if( rate === 0 || now - lastEmit < 1/rate )	return;
		lastEmit	= now;

		// init sprite material
		var material	= new THREE.SpriteMaterial({
			map			: texture,
			useScreenCoordinates	: false