var Backdrop = {
  init: function(num,image,speed,container) {
    container = document.getElementById(container);
    var images = {}; 
    	for (var i = 0;i < num; i++) {
 			images[i] = document.createElement('img');
 			images[i].src = image;
 			images[i].style.top = Math.floor(Math.random()*201) + 'px';
 			images[i].style.left = Math.floor(Math.random()*1001) + 'px';
 			container.appendChild(images[i]);
 			Backdrop.animate(images[i],speed);
  		}	
  },
  animate: function(img,speed) {
  currentPos = parseInt(img.style.left);
  if (currentPos >= 0) {
		newPos = currentPos - speed;
		img.style.left = newPos + 'px';
        } else {
        	img.style.left = '1000px';
        	img.style.top = Math.floor(Math.random()*201) + 'px';
        	}
  setTimeout(function(){Backdrop.animate(img,speed)},50);
  }
};

window.onload = function () {
	Backdrop.init(80,'images/starbright.png',1,'header');
	Backdrop.init(30,'images/starmed.png',3,'header');
    Backdrop.init(20,'images/stardark.png',5,'header');
    /*Scroll.init(5,'images/cloud.png',1,'header');*/
   	}