,
			color			: 0xAA4488,
			transparent		: true,
			blending		: THREE.AdditiveBlending
		})
		// init sprite
		var sprite	= new THREE.Sprite(material)
		//sprite.rotation	= Math.random() * Math.PI*2
		sprite.position.copy( position )
		container.add( sprite )

		// compute velocity
		var velocity	= position.clone().sub(prevPosition).normalize();
		prevPosition.copy( position )

		// start a little bit behind the container
		sprite.position.add( velocity.clone().multiplyScalar(-0.1) )
		// init pattern
		spr