jQuery 图片跟随鼠标浮动

不知你有没注意到我的网站首页，上面浮动着一层雪花的背景，并且随着鼠标的移动也在移动着。

本文主要讲述了如何判断鼠标的位置，从而实现图片跟随鼠标进行浮动。为了方便查看和理解，在Demo的左下角把各个参数都打印了出来。

CSS CODE:

<style type="text/css">
*{ margin:0; padding:0;}
body{ font-family:Arial; font-size:12px; background:url(bg.png) no-repeat; background-position:center center; background-attachment:fixed;}
input{ width:100px;}
span{ display:inline-block; width:120px;}
#window{ color:white; position:absolute; bottom:10px; left:10px;}
#coordinate{ color:white; position:absolute; bottom:35px; left:10px;}
#location{ color:white; position:absolute; bottom:60px; left:10px;}
#float_bg{ width:2496px; height:1060px; background:url(float_bg.png) no-repeat; position:fixed;}
</style>

HTML CODE:

<div id="float_bg"></div>
<div id="window">
	<span id="window_x"></span>
	<span id="window_y"></span>
</div>
<div id="location">
	<span id="location_x"></span>
	<span id="location_y"></span>
</div>
<div id="coordinate">
	<span id="mouse_x"></span>
	<span id="mouse_y"></span>
</div>
<div id="test">
	<span id="test_a"></span>
	<span id="test_b"></span>
</div>

JAVASCRIPT CODE:

$(function(){
	var my=0,mx=0;
	$(document).mousemove(function(e){
		var x=e.pageX,y=e.pageY;
		if(mx==0) mx=x;
		if(my==0) my=y;
		ml = x-mx;
		ml = Math.ceil(ml/150); //将小数部分一律向整数部分进位。如：Math.ceil(10.0) 返回10 / Math.ceil(10.1) 返回11 
		$('#float_bg').css('left',ml);
		mt = y-my;
		mt = Math.ceil(mt/100);
		$('#float_bg').css('top',mt);

		var doc_width 	= $(document).width();
		var doc_height	= $(document).height();
		var half_height	= doc_width/2;
		var half_width	= doc_height/2;
		$("#window_x").text( "Width: " + doc_width );
		$("#window_y").text( "Height: " + doc_height);
		$("#mouse_x").text( "Abscissa: " + x );
		$("#mouse_y").text( "Ordinate: " + y );
		if( half_height > x){ //鼠标的x位置
			$("#location_x").text( "Location: Left" );
		}else{
			$("#location_x").text( "Location: Right" );
		}
		if( half_width > y){ //鼠标的y位置
			$("#location_y").text( "Location: Up" );
		}else{
			$("#location_y").text( "Location: Down" );
		}
	});
});

DemoDownload