// <![CDATA[
var speed=20; // how fast - smaller is faster
var colours=new Array("#f00", "#f60", "#f93", "#fa5", "#fb6", "#fc7", "#fd8", "#fe9", "#ffa", "#ffb", "#ffc");
// above line lists colours for the comet and its tail (can be as long or short as you like)

/****************************
* Shooting Star/Comet Effect*
* (c) 2008 mf2fm web-design *
*  http://www.mf2fm.com/rv  *
* DON'T EDIT BELOW THIS BOX *
****************************/
var dx, dy;
var xpos=new Array();
var ypos=new Array();
var swide=800;
var shigh=600;
var tail=colours.length;

function write_comet() {
  var b, t, s;
  b=document.createElement("div");
  b.style.position="absolute";
  b.setAttribute("id", "bod");
  document.body.appendChild(b);
  set_scroll();
  set_width();
  for (i=0; i<tail; i++) {
    s=1+(i<tail/4)+(!i);
	t=div("comet"+i, s, s);
	b.appendChild(t);
  }
}

function div(id, w, h) {
  var d=document.createElement("div");
  d.style.position="absolute";
  d.style.overflow="hidden";
  d.style.width=w+"px";
  d.style.height=h+"px";
  d.setAttribute("id", id);
  return (d);
}

function stepthrough() {
  var i;
  if (Math.random()<0.008||ypos[0]+dy<4||xpos[0]+dx<4||xpos[0]+dx>=swide-4||ypos[0]+dy>=shigh-4) {
	for (i=0; i<tail; i++) setTimeout('document.getElementById("comet'+i+'").style.backgroundColor="transparent"', speed*(tail-i));
	setTimeout('launch()', 1000+Math.random()*9000);
  }
  else setTimeout('stepthrough()', speed);
  for (i=tail-1; i>=0; i--) {
	if (i) {
      xpos[i]=xpos[i-1];
      ypos[i]=ypos[i-1];
	}
	else {
	  xpos[i]+=dx;
      ypos[i]+=dy;
	}
    document.getElementById("comet"+i).style.left=xpos[i]+"px";
    document.getElementById("comet"+i).style.top=ypos[i]+"px";
  }
}

function launch() {
  var i;
  dx=(Math.random()>0.5?1:-1)*(2+Math.random()*3);
  dy=(Math.random()>0.5?1:-1)*(2+Math.random()*3);
  xpos[0]=2*tail*dx+Math.round(Math.random()*(swide-4*tail*dx));
  ypos[0]=2*tail*dy+Math.round(Math.random()*(shigh-4*tail*dy));
  for (i=0; i<tail; i++) {
    xpos[i]=xpos[0];
    ypos[i]=ypos[0];
	document.getElementById("comet"+i).style.backgroundColor=colours[i];
  }
  stepthrough();
}

window.onscroll=set_scroll;
function set_scroll() {
  var sleft, sdown;
  if (typeof(self.pageYOffset)=="number") {
    sdown=self.pageYOffset;
    sleft=self.pageXOffset;
  }
  else if (document.body.scrollTop || document.body.scrollLeft) {
    sdown=document.body.scrollTop;
    sleft=document.body.scrollLeft;
  }
  else if (document.documentElement && (document.documentElement.scrollTop || document.documentElement.scrollLeft)) {
    sleft=document.documentElement.scrollLeft;
	sdown=document.documentElement.scrollTop;
  }
  else {
    sdown=0;
    sleft=0;
  }
  var s=document.getElementById("bod").style;
  s.top=sdown+"px";
  s.left=sleft+"px";
}

window.onresize=set_width;
function set_width() {
  if (typeof(self.innerWidth)=="number") {
    swide=self.innerWidth;
    shigh=self.innerHeight;
  }
  else if (document.documentElement && document.documentElement.clientWidth) {
    swide=document.documentElement.clientWidth;
    shigh=document.documentElement.clientHeight;
  }
  else if (document.body.clientWidth) {
    swide=document.body.clientWidth;
    shigh=document.body.clientHeight;
  }
}

window.onload=function() { if (document.getElementById) {
  set_width();
  write_comet();
  launch();
}}
// ]]>