制作下雨效果实例代码
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>标题页</title>
</head>
<body>
<script language="JavaScript">
var no = 50;
var speed = 1;
var ns4up = (document.layers) ? 1 : 0; //针对netscape时，使用的对象-document.layers
var ie4up = (document.all) ? 1 : 0; //针对ie时，使用的对象-document.all
var s, x, y, sn, cs;
var a, r, cx, cy;
var i, doc_width = 800, doc_height = 600; //设置窗体的初始高度和宽度
if (ns4up) { //netscape时，获取窗体的高度和宽度
doc_width = self.innerWidth;
doc_height = self.innerHeight;
}
else
if (ie4up) { //ie时，获取窗体的高度和宽度
doc_width = document.body.clientWidth;
doc_height = document.body.clientHeight;
}
x = new Array();
y = new Array();
r = new Array();
cx = new Array();
cy = new Array();
s = 8;
for (i = 0; i < no; ++ i) {
initRain(); //
if (ns4up) { //netscape时，使用layer设置一些动态雨点
if (i == 0) {
document.write("<layer name=\"dot"+ i +"\" left=\"1\" ");
document.write("top=\"1\" visibility=\"show\"><font color=\"blue\">");
document.write(",</font></layer>");
}
else {
document.write("<layer name=\"dot"+ i +"\" left=\"1\" ");
document.write("top=\"1\" visibility=\"show\"><font color=\"blue\">");
document.write(",</font></layer>");
}
}
else
if (ie4up) { //IE时，使用div设置一些动态雨点
if (i == 0) {
document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
document.write("visible; TOP: 15px; LEFT: 15px;\"><font color=\"blue\">");
document.write(",</font></div>");
}
else {
document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
document.write("visible; TOP: 15px; LEFT: 15px;\"><font color=\"blue\">");
document.write(",</font></div>");
}
}
}
function initRain() { //初始化坐标值-动态
a = 6;
r[i] = 1;
sn = Math.sin(a);
cs = Math.cos(a);
cx[i] = Math.random() * doc_width + 1;
cy[i] = Math.random() * doc_height + 1;
x[i] = r[i] * sn + cx[i];
y[i] = cy[i];
}
function makeRain() { //设置动态的x,y坐标
r[i] = 1;
cx[i] = Math.random() * doc_width + 1;
cy[i] = 1;
x[i] = r[i] * sn + cx[i];
y[i] = r[i] * cs + cy[i];
}
function setRain() { //重新生成x,y坐标
r[i] += s;
x[i] = r[i] * sn + cx[i];
y[i] = r[i] * cs + cy[i];
}
function raindropNS() { //在netscape中的下雨效果
for (i = 0; i < no; ++ i) {
setRain();
if ((x[i] <= 1) || (x[i] >= (doc_width - 20)) || (y[i] >= (doc_height - 20))) {
makeRain();
doc_width = self.innerWidth;
doc_height = self.innerHeight;
}
document.layers["dot"+i].top = y[i];
document.layers["dot"+i].left = x[i];
}
setTimeout("raindropNS()", speed);
}
function raindropIE() { //在IE中的下雨效果
for (i = 0; i < no; ++ i) {
setRain();
if ((x[i] <= 1) || (x[i] >= (doc_width - 20)) || (y[i] >= (doc_height - 20))) {
makeRain();
}
document.all["dot"+i].style.pixelTop = y[i]; //循环改变雨点的x和y坐标
document.all["dot"+i].style.pixelLeft = x[i];
}
setTimeout("raindropIE()", speed); //实现定时器，实现不断下雨的效果
}
if (ns4up) {
raindropNS();
}
else
if (ie4up) {
raindropIE();
}
</script>
</body>
</html>
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