var xPos = 400;//(screen.width-document.body.clientWidth)/2;
var yPos = 200; 
var step = 3;
var delay = 50; 
var height = 0;
var Hoffset = netease.offsetHeight;
var Woffset = netease.offsetWidth;
var yon = 0;
var xon = 0;
var pause = true;
var interval;

function changePos(){
	sHeight = document.documentElement.clientHeight;
	sTop = document.documentElement.scrollTop;
	width = document.body.clientWidth;
	height = sHeight + sTop;
	
	netease.style.left = xPos ;
	netease.style.top = yPos ;
	
	if (yon){
		yPos = yPos + step;
	}else{
		yPos = yPos - step;
	}
	if (yPos < sTop){
		yon = 1;
		yPos = sTop;
	}
	if (yPos >= (height - Hoffset)){
		yon = 0;
		yPos = (height - Hoffset);
	}
		
	if (xon){
		xPos = xPos + step;
	}else{
		xPos = xPos - step;
	}
	if (xPos < 0){
		xon = 1;
		xPos = 0;
	}
	if (xPos >= (width - Woffset)){
		xon = 0;
		xPos = (width - Woffset);   
	}
}	
function start(){
	netease.visibility = "visible";
	interval = setInterval('changePos()', delay);
}
function pause_resume(){
	if(pause){
		clearInterval(interval);
		pause = false;
	}else{
		interval = setInterval('changePos()',delay);
		pause = true; 
	}
}
start();