本文實例講述了jQuery模擬物體自由落體運動的方法。分享給大家參考，具體如下：
運作效果截圖如下：
點擊此處查看線上簡報效果。
完整實例程式碼點擊此處本站下載。
具體程式碼如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>自由落体</title>
<script src="jquery-1.7.1.min.js" type="text/javascript"></script>
<script type="text/javascript" >
$(document).ready(function () {
});
var all_Height = 500;
var a = 9.8; // 加速度
var v = 0;
var prev_Time = 0;
var prev_Speed = 0;
var prev_Height = 0;
var speed = 0;
// 获取当前的高度
var getHeight = function (obj) {
return obj.offset().top;
}
// 获取当前的速度
var getSpeed = function (time, a) {
return time * a;
}
// 向下走时获得当前物体所走的路径
var getCurrentHeight = function (time) {
return 1 / 2 * a * time * time;
}
// 向上走时获得当前物体所走的路径
var getCurrentHeight2 = function (speed, time) {
return speed * time - 1 / 2 * a * time * time;
}
// 向下跑
function down() {
prev_Time = 0;
var interval = setInterval(function () {
if (getHeight($(".obj")) < all_Height) {
prev_Time = prev_Time + 0.1;
var height = getCurrentHeight(prev_Time) + prev_Height;
$(".obj").css("top", height + "px");
$(".info").append("<div>" + height + "</div>");
} else {
speed = getSpeed(a, prev_Time);
prev_Speed = speed;
clearInterval(interval);
up();
}
}, 5);
}
// 向上跑
function up() {
prev_Time = 0;
prev_Speed -= 4; // 动能损耗
var interval = setInterval(function () {
if (speed > 0) {
speed = prev_Speed - getSpeed(a, prev_Time);
prev_Time = prev_Time + 0.1;
var height = all_Height - getCurrentHeight2(prev_Speed, prev_Time);
$(".obj").css("top", height + "px");
} else {
clearInterval(interval);
prev_Height = $(".obj").offset().top;
if (prev_Height < all_Height) {
down();
}
}
}, 5);
}
function play() {
alert('play');
down();
document.getElementById("obj").onclick = null;
}
</script>
<style type="text/css">
body{ margin:0 0 0 0 ; background:#FFFFFF;}
.title { text-align:center; color:#666666; border-bottom:2px solid gray; font-size:30px; line-height:100px; font-weight:bolder;}
.obj { background-image:url('a.jpg'); width:50px; height:50px; position:absolute; top:0; left:0; }
</style>
</head>
<body>
<div style="height:550px; border-bottom:2px solid gray;">
<div class="title" >自由落体大模拟<span style="font-size:12px;">(点击图片让它落下)</span></div>
</div>
<div class="obj" id="obj" onclick="play();" ></div>
</body>
</html>
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更多關於js運動相關內容有興趣的讀者可查看本站專題：《JavaScript運動效果與技巧匯總》
希望本文所述對大家jQuery程式設計有所幫助。
