js碰撞检测

yuan010101 2021-08-14 原文

这篇文章主要介绍了JS实现判断碰撞的方法,实例分析了通过js判断实体碰撞的技巧与相关应用,需要的朋友可以参考下

<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN” “http://www.w3.org/TR/html4/loose.dtd”>
<html>
<head>
<title> demo </title>
<style type=”text/css”>
body{margin:0px;}
    .main{position:relative;}
    #f1{position:absolute; background:#FF0000; top:100px; left:100px; width:200px; height:200px; z-index:999}
    #f2{position:absolute; background:#FFFF00; top:0px; left:0px; width:600px; height:150px;}
</style>
</head>
<body>
<div class=”main”>
    <div id=”f1″></div>
    <div id=”f2″></div>
</div>
<script type=”text/javascript”>
    var o = document.getElementById(“f1”);
    var d = document.getElementById(“f2”);
    alert(impact(o, d));

    function impact(obj, dobj) {
        var o = {
            x: getDefaultStyle(obj, \’left\’),
            y: getDefaultStyle(obj, \’top\’),
            w: getDefaultStyle(obj, \’width\’),
            h: getDefaultStyle(obj, \’height\’)
        }

        var d = {
            x: getDefaultStyle(dobj, \’left\’),
            y: getDefaultStyle(dobj, \’top\’),
            w: getDefaultStyle(dobj, \’width\’),
            h: getDefaultStyle(dobj, \’height\’)
        }

var px, py;

        px = o.x <= d.x ? d.x : o.x;
        py = o.y <= d.y ? d.y : o.y;

        // 判断点是否都在两个对象中
        if (px >= o.x && px <= o.x + o.w && py >= o.y && py <= o.y + o.h && px >= d.x && px <= d.x + d.w && py >= d.y && py <= d.y + d.h) {
            return true;
        } else {
            return false;
        }
    }

    function getDefaultStyle(obj, attribute) {
        return parseInt(obj.currentStyle ? obj.currentStyle[attribute] : document.defaultView.getComputedStyle(obj, false)[attribute]);
    }
</script>
</body>
</html>