<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title>飞机大战</title>
<style>
#did{
width:500px;height:500px;
background:url("./images/bg2.png") no-repeat 0px -1036px;
position:relative;overflow:hidden;}
#gid{position:absolute;top:350px;left:100px;}
#p0,#p1,#p2,#p3,#p4,#e1,#e2,#e3,#boom{position:absolute;}
</style>
</head>
<body>
<h2>JavaScript实例:飞机大战</h2>
<div id="did">
<img id="p0" src="./images/eshot.png" style="display:none;"/>
<img id="p1" src="./images/eshot.png" style="display:none;"/>
<img id="p2" src="./images/eshot.png" style="display:none;"/>
<img id="p3" src="./images/eshot.png" style="display:none;"/>
<img id="p4" src="./images/eshot.png" style="display:none;"/>
<img id="e1" src="./images/e1.png" style="display:none;"/>
<img id="e2" src="./images/e2.png" style="display:none;"/>
<img id="e3" src="./images/e3.png" style="display:none;"/>
<img id="boom" src="./images/boom.gif" style="display:none;"/>
<img id="gid" src="./images/me.png"/>
</div>
<script type="text/javascript">
var btop=-1036;
var m=0,b=0;
var did = document.getElementById("did");
var gid = document.getElementById("gid");
var boom = document.getElementById("boom");
window.document.onkeydown = function(ent){
//获取兼容的事件对象
var event = ent || window.event;
//alert(event.keyCode);
//根据键盘值执行对应操作
switch(event.keyCode){
case 37: //左方向键
gid.style.left = Math.max(0,gid.offsetLeft-5)+"px";
break;
case 38: //上方向键
gid.style.top = Math.max(0,gid.offsetTop-5)+"px";
break;
case 39: //右方向键
gid.style.left = Math.min(450,gid.offsetLeft+5)+"px";
break;
case 40: //下方向键
gid.style.top = Math.min(440,gid.offsetTop+5)+"px";
break;
case 32: //空格键
shoot(gid.offsetLeft+51,gid.offsetTop); //发射炮弹
break;
}
}
//发射炮弹方法
function shoot(x,y){
//遍历所有炮弹
for(var i=0;i<5;i++){
var p = document.getElementById("p"+i);
//判断炮弹是否可用
if(p.style.display=="none"){
p.style.top = y+"px";
p.style.left = x+"px";
p.style.display = "block";
return;
}
}
}
//碰撞检测函数
function doCheckP(p,e){
//获取检测坐标
var x1 = e.offsetLeft+3;
var x2 = e.offsetLeft+93;
var y1 = e.offsetTop+35;
var y2 = e.offsetTop+59;
var x = p.offsetLeft+1;
var y = p.offsetTop;
//判断是否有像素重叠
if(x>x1 && x<x2 && y>y1 && y<y2){
return true;
}
return false;
}
//游戏主线程
function running(){
//负责移动可见炮弹
for(var i=0;i<5;i++){
var p = document.getElementById("p"+i);
//判断炮弹是否可用
if(p.style.display=="block"){
p.style.top = p.offsetTop-5+"px";
//回收出了屏幕的炮弹
if(p.offsetTop<-10){
p.style.display = "none";
}
//碰撞检测
//遍历所有敌机
for(var j=1;j<=3;j++){
var e = document.getElementById("e"+j);
//判断是否可见
if(e.style.display=="block"){
if(doCheckP(p,e)){
//设置爆炸位置
boom.style.top = p.offsetTop-170+"px";
boom.style.left = p.offsetLeft-200+"px";
boom.style.display ="block";
b=0;
//隐藏敌机和炮弹
p.style.display = "none";
e.style.display = "none";
}
}
}
}
}
//随机设置出现敌机
var n = Math.ceil(Math.random()*10000)%20;
if(n==5){
for(var i=1;i<=3;i++){
var e = document.getElementById("e"+i);
//判断而是否可用
if(e.style.display=="none"){
e.style.display="block";
e.style.top=-85+"px";
e.style.left=Math.ceil(Math.random()*10000)%400+"px";
break;
}
}
}
//负责移动可见飞机
for(var i=1;i<=3;i++){
var e = document.getElementById("e"+i);
//判断而是否可用
if(e.style.display=="block"){
e.style.top = e.offsetTop+4+"px";
//判断是否出界
if(e.offsetTop>500){
e.style.display = "none";
}
}
}
//控制爆炸时间
if(b>=0){
b++;
}
if(b>10){
boom.style.display ="none";
b=-1;
}
//负责无缝滚动背景图片
m+=2;
did.style.backgroundPosition="0px "+(btop+m)+"px";
if(m>768){
m=0;
}
setTimeout("running()",33);
}
running();
</script>
</body>
</html>
时间： 2024-12-15 06:37:26