自由落体和抛物线运动

自由落体是个加速的过程，让速度递加，再给速度个系数，减小速度即可

抛物线是在自由落体的前提下left也会变，速度，速度系数

 

js函数

//自由落体和抛物线运动
function fallMove(obj) {
    var speed = 0;
    var speedX = 10;
    clearInterval(obj.timer);
    obj.timer = setInterval(function() {
        speed += 3;
        var T = obj.offsetTop + speed;
        if(T > document.documentElement.clientHeight - obj.offsetHeight) {
            T = document.documentElement.clientHeight - obj.offsetHeight;
            speed *= -1;
            speed *= 0.75;
            speedX *= .75;
        }
        if(Math.abs(speed) <= 2 && Math.abs(T - (document.documentElement.clientHeight - obj.offsetHeight)) <= 1) {
            clearInterval(obj.timer);
        }
        obj.style.top = T + 'px';
        obj.style.left = obj.offsetLeft + speedX + 'px';
        //                        console.log(obj.offsetLeft);
    }, 30);
}

 

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
        <link rel="stylesheet" type="text/css" href="../css/public.css"/>
        <style type="text/css">
            #div1{width: 100px;height: 100px;background: red;position: absolute;top: 30px;left: 0;}
        </style>
        <script type="text/javascript" src="../js/rainbow.js"></script>
        <script type="text/javascript">
            window.onload=function(){
                var oDiv=document.getElementById("div1");
                var oBtn=document.getElementById("btn");
                oBtn.onclick=function(){
                    fallMove(oDiv);
                }
            }
        </script>
    </head>
    <body>
        <input type="button" name="btn" id="btn" value="自由落体" />
        <div id="div1"></div>
    </body>
</html>

 

posted @ 2016-11-27 21:46  rain92  阅读(1967)  评论(0)  编辑  收藏  举报