js原生碰撞检测

时间：2022-04-21 18:21:14
<!doctype html>

<html>

<head>

<meta charset="utf-8">

<title>无标题文档</title>

<style>

div{width:100px;

    height:100px;

}

#box{background:red; position:absolute; }

#box1{background:green;position:absolute;top:300px; left:300px;}

</style>

<script>

//两个碰撞的盒子。是建立在一个不动的基础上。所以可以根据不动的盒子求出四个方向的left和top值。然后再判断其是否碰撞，且碰撞的过程随时改变其层级，（原需 var 8个变量，现在只需4个变量）

function collText(obj,left,top,obj1){

            var l1=obj.offsetLeft-obj.offsetWidth;

            var t1=obj.offsetTop-obj.offsetHeight;

            var r1=obj.offsetLeft+obj.offsetWidth;

            var b1=obj.offsetTop+obj.offsetHeight;

            if(left<l1||top<t1||left>r1||top>b1){

                obj.style.zIndex=;

                obj1.style.zIndex=;

                return true;

            }else{

                obj.style.zIndex=;

                obj1.style.zIndex=;

                return false;

            }

};

window.onload=function(){

    var oBox=document.getElementById('box');

    var oBox1=document.getElementById('box1');

    oBox.onmousedown=function(ev){

        var oEvent= ev   ||    event;

        var disX=oEvent.clientX-oBox.offsetLeft;

        var disY=oEvent.clientY-oBox.offsetTop;

        document.onmousemove=function(ev){

            var oEvent= ev  ||    event;

            var l=oEvent.clientX-disX;

            var t=oEvent.clientY-disY;

            oBox.style.left=l+'px'    ;

            oBox.style.top=t+'px'    ;

            if(collText(oBox1,l,t,oBox)){

                oBox1.style.background='green';

            }else{

                oBox1.style.background='yellow';

            }

        };

        document.onmouseup=function(){

            document.onmousemove=null;

            document.onmouseup=null;

            oBox.reseaseCapture&&oBox.reseaseCapture();

        };

        oBox.setCapture&&oBox.setCapture();

        return false;

    }

    oBox1.onmousedown=function(ev){

        var oEvent= ev ||    event;

        var disX1=oEvent.clientX-oBox1.offsetLeft;

        var disY1=oEvent.clientY-oBox1.offsetTop;

        document.onmousemove=function(ev){

            var oEvent= ev ||    event;

            var le=oEvent.clientX-disX1;

            var to=oEvent.clientY-disY1;

            oBox1.style.left=le+'px'    ;

            oBox1.style.top=to+'px'    ;

            if(collText(oBox,le,to,oBox1)){

                oBox.style.background='red';

            }else{

                oBox.style.background='#000';

            }

        };

        document.onmouseup=function(){

            document.onmousemove=null;

            document.onmouseup=null;

            oBox1.reseaseCapture&&oBox1.reseaseCapture();

        }

        oBox1.setCapture&&oBox1.setCapture();

        return false;

    }

}

</script>

</head>

<body>

<div id="box"></div>

<div id="box1"></div>

</body>

</html>

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