var ie = (document.attachEvent ? true : false);

function init_stars(){
	stars = byClassName('img', 'star');
	for(var i=0; i<stars.length; i++){
		star = stars[i];
		var opacity = Math.random()*100;
		star.style.opacity = (opacity/100);
		star.style.filter = 'alpha(opacity='+opacity+')';
		star.id = 'star'+i;
		var timer = Math.floor((150-80)*Math.random())+80;
		if(ie) timer = timer/2;
		sparkle(star.id, opacity, timer);
	}
	
	if(!ie){
		var timer = Math.floor((1000*60*3)*Math.random());
		setTimeout('movingstar('+1000+')', timer);
	}
}

function byClassName(tag, className){
	var list = new Array();
	var elements = document.getElementsByTagName(tag);
	for(var i=0; i<elements.length; i++){
		if(elements[i].className == className){
			list[list.length] = elements[i];
		}
	}
	return list;
}

function sparkle(star, opacity, timer, reverse){
	star = document.getElementById(star);
	reverse = (opacity > 100 || opacity < 0 ? !reverse : reverse);
	opacity = opacity+(reverse ? -10 : +10);
	star.style.opacity = (opacity/100);
	star.style.filter = 'alpha(opacity='+opacity+')';
	
	setTimeout('sparkle(\''+(star.id)+'\', '+opacity+', '+timer+', '+reverse+')', timer);
}

function movingstar(x){
	document.getElementById('movingstar').style.display = '';

	x = x-15;
	var x_param = x/40;
	var y_param = Math.log(2*x_param);
	var y = 130-(y_param*35);
	document.getElementById('movingstar').style.marginLeft = (x-480)+'px';
	document.getElementById('movingstar').style.top = y+'px';
	
	if(y<80){
		setTimeout('movingstar('+x+')', 20);
	}
	else{
		document.getElementById('movingstar').style.display = 'none';
		var timer = Math.floor((1000*60*3)*Math.random());
		setTimeout('movingstar('+1000+')', timer);
	}
}