<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
*{margin:0;padding:0;}
div{
position: absolute;
width: 100px;
height: 100px;
font-size: 25px;
line-height: 100px;
text-align: center;
border-radius:50%;
}
#move_box{
background: red;
cursor: pointer;
}
#hit_box{
left: 200px;
top: 200px;
background: blue;
}
#hit_box2{
left: 350px;
top: 200px;
background: blue;
/*height: 150px;*/
border-radius:50%;
}
</style>
</head>
<body>
<div id="move_box">移动</div>
<div id="hit_box">被撞</div>
<div id="hit_box2">被撞</div>
</body>
<script>
// 获取元素对象
var moveBox = document.getElementById("move_box");
// var hitBoxes = document.querySeletorAll("#hit_box #hit_box2");
var hitBox = document.getElementById("hit_box");
var hitBox2 = document.getElementById("hit_box2");
var hitBoxes = [hitBox,hitBox2];
// 碰撞函数
function circleHit(circle1,circle2){
// 移动对象园的偏移量
var r1 = circle1.offsetWidth / 2;
var l1 = circle1.offsetLeft;
var t1 = circle1.offsetTop;
// 被撞对象的圆偏移量
var r2 = circle2.offsetWidth / 2; //园2的半径
var l2 = circle2.offsetLeft;
var t2 = circle2.offsetTop;
//用圆1的偏离量+园1的半径 - 园2的偏移量 + 园2的半径
var a = (l1 + r1) - (l2 + r2); // 左偏移量
var b = (t1 + r1) - (t2 + r2); //上偏移量
//勾股定理求两个圆的圆心距离
var c = Math.sqrt(a * a + b * b);
if (c>=(r1+r2)) {
return true;
}else{
return false;
}
}
// 为移动元素添加鼠标按下的事件
moveBox.onmousedown = function(event){
var event = event || window.event;
// 获取鼠标在移动元素内的坐标点
var disX = event.clientX - moveBox.offsetLeft;
var disY = event.clientY - moveBox.offsetTop;
// 为doc文档添加移动事件
document.onmousemove = function(event){
var event = event || window.event;
// 获取移动距离的偏移量
var x = event.clientX - disX;
var y = event.clientY - disY;
// 循环每一个被撞的对象
for (var i = 0; i < hitBoxes.length; i++) {
// 调用被撞函数
var bool = circleHit(moveBox,hitBoxes[i]);
// 判断
if (bool) {
hitBoxes[i].style.backgroundColor = "blue";
hitBoxes[i].innerHTML = "被撞";
}else{
hitBoxes[i].style.backgroundColor = "green";
hitBoxes[i].innerHTML = "撞上";
}
}
moveBox.style.left = x + "px";
moveBox.style.top = y + "px";
}
}
// 鼠标抬起
moveBox.onmouseup = function(){
document.onmousemove = null;
}
</script>
</html>
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