夜空中飞舞的星星

下面为效果显示

点击这里下载本特效相关图片

脚本说明:
把如下代码加入<body>区域中：
<script language="JavaScript1.2">
grphcs=new Array(5)

//PRELOAD the involved images (extend or contract variables according to # of images used)
Image0=new Image();
Image0.src=grphcs[0]="Star0.gif"
Image1=new Image();
Image1.src=grphcs[1]="Star1.gif"
Image2=new Image();
Image2.src=grphcs[2]="Star2.gif"
Image3=new Image();
Image3.src=grphcs[3]="Star3.gif"
Image4=new Image();
Image4.src=grphcs[4]="Star4.gif"

//SPECIFY number of images to randomly display concurrently from list above. Less the more efficient
Amount=20; 
Ypos=new Array();
Xpos=new Array();
Zpos=new Array();
//SpeedX=new Array();
//SpeedY=new Array();
ScrXpos=new Array();
ScrYpos=new Array();
Speed=new Array();
Size=new Array();
Step=new Array();
ns=(document.layers)?1:0;
ie=document.all&&navigator.userAgent.indexOf("Opera")==-1

if (ns){
for (i = 0; i < Amount; i++){
var P=Math.floor(Math.random()*grphcs.length);
rndPic=grphcs[P];
document.write("<LAYER NAME='sn"+i+"' LEFT=0 TOP=0><img src="+rndPic+"></LAYER>");
} //end for
} //end if
else if (ie){ //IE
document.write('<div style="position:absolute;top:0px;left:0px"><div style="position:relative">');
for (i = 0; i < Amount; i++){
document.write('<img id="si'+i+'" src="'+grphcs[Math.round((i+1)*(grphcs.length-1)/Amount)]+'"style="position:absolute;top:0px;left:0px">');
}
document.write('</div></div>');
}

//initialize star properties
if (ie||ns){
WinHeight=(ns)?window.innerHeight-20:window.document.body.clientHeight;
WinWidth=(ns)?window.innerWidth-70:window.document.body.clientWidth;
for (i=0; i < Amount; i++){
Speed[i]=(i+1)*6/Amount+4; //speed range from 4 to 10
Xpos[i] = (Math.random()*WinWidth-WinWidth/2)*(Amount-i/3)/Amount;
Ypos[i] = (Math.random()*WinHeight-WinHeight/2)*(Amount-i/3)/Amount;
Zpos[i] = Math.random()*900*(Amount-i/3)/Amount+100;
}
}

function fly(){
var WinHeight=(ns)?window.innerHeight-20:window.document.body.clientHeight;
var WinWidth=(ns)?window.innerWidth-70:window.document.body.clientWidth;
var hscrll=(ns)?window.pageYOffset:document.body.scrollTop;

for (i=0; i < Amount; i++){
Zpos[i]-=Speed[i];
if (ScrXpos[i]>WinWidth || ScrXpos[i]<0 || ScrYpos[i]>WinHeight || ScrYpos[i]<0 || Zpos[i]<=0) { //generate new stars
Speed[i]=(i+1)*6/Amount+4; //speed range from 4 to 10
Xpos[i] = (Math.random()*WinWidth-WinWidth/2)*(Amount-i/3)/Amount;
Ypos[i] = (Math.random()*WinHeight-WinHeight/2)*(Amount-i/3)/Amount;
Zpos[i] = Math.random()*900*(Amount-i/3)/Amount+100;
}
ScrXpos[i]=Xpos[i]/Zpos[i]*100 + WinWidth/2;
ScrYpos[i]=Ypos[i]/Zpos[i]*100 + WinHeight/2;

if (ns){
document.layers['sn'+i].left=ScrXpos[i];
document.layers['sn'+i].top=ScrYpos[i]+hscrll;
}
else{ //IE
eval("document.all.si"+i).style.left=ScrXpos[i];
eval("document.all.si"+i).style.top=ScrYpos[i]+hscrll;
}
} //end for
setTimeout('fly()',20);
} //end fly

if (ie||ns)
window.onload=fly
//-->
</SCRIPT>