demo1：
1.通过设置CSS样式的position属性，z-index属性等实现背景图，转盘图与指针图的层叠摆放；
2、通过设置元素style.transform = "rotate(0deg)"实现旋转效果；
代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>转盘抽奖</title>
<style>
#bg {
650px;
height: 600px;
margin: 0 auto;
background: url(turntable-bg.jpg) no-repeat;
position: relative;
}
img[src^="pointer"] {
position: absolute;
z-index: 10;
top: 155px;
left: 247px;
}
img[src^="turntable"] {
position: absolute;
z-index: 5;
top: 60px;
left: 116px;
transition: all 4s;
}
</style>
</head>
<body>
<div id="bg"><img src="pointer.png" alt="pointer"><img src="turntable.png" alt="turntable"></div>
<script>
var oPointer = document.getElementsByTagName("img")[0];
var oTurntable = document.getElementsByTagName("img")[1];
var cat = 360/7; //总共7个扇形区域，每个区域角度
var num = 0; //转圈结束后停留的度数
var offOn = true; //是否正在抽奖
oPointer.onclick = function () {
if (offOn) {//正在抽奖
oTurntable.style.transform = "rotate(0deg)";
offOn = !offOn;//转盘停止转动
ratating();//调用旋转函数
}
}
//旋转
function ratating() {
var timer = null;
var rdm = 0; //随机度数
clearInterval(timer);
timer = setInterval(function () {
if (Math.floor(rdm / 360) < 3) {
rdm = Math.floor(Math.random() * 3600);
//console.log("rdm:==="+rdm);
} else {
oTurntable.style.transform = oTurntable.style.webkitTransform= "rotate(" + rdm + "deg)";
clearInterval(timer);
setTimeout(function () {
offOn = !offOn;
num = rdm % 360;
if (num <= cat * 1) {
alert("4999元");
console.log("rdm=" + rdm + "，num=" + num + "，" + "4999元");
} else if (num <= cat * 2) {
alert("50元");
console.log("rdm=" + rdm + "，num=" + num + "，" + "50元");
} else if (num <= cat * 3) {
alert("10元");
console.log("rdm=" + rdm + "，num=" + num + "，" + "10元");
} else if (num <= cat * 4) {
alert("5元");
console.log("rdm=" + rdm + "，num=" + num + "，" + "5元");
}
else if (num <= cat * 5) {
alert("免息服务");
console.log("rdm=" + rdm + "，num=" + num + "，" + "免息服务");
}
else if (num <= cat * 6) {
alert("提交白金");
console.log("rdm=" + rdm + "，num=" + num + "，" + "提交白金");
}
else if (num <= cat * 7) {
alert("未中奖");
console.log("rdm=" + rdm + "，num=" + num + "，" + "未中奖");
}
}, 4000);
}
}, 30);
}
</script>
</body>
</html>
运行效果：点击抽奖转盘旋转
素材：
demo2：
涉及知识点：
贝塞尔曲线
cubic-bezier还是比较少用到，PC端中，有浏览器不兼容。但是手机端中，可以使用并带来炫酷的动画及体验。
- 缓动函数速查表： http://www.xuanfengge.com/easeing/easeing/
- Ceaser： http://xuanfengge.com/easeing/ceaser/
- cubic-bezier：http://cubic-bezier.com/
cubic-bezier即为贝塞尔曲线中的绘制方法。图上有四点，P0-3，其中P0、P3是默认的点，对应了[0,0], [1,1]。而剩下的P1、P2两点则是我们通过cubic-bezier()自定义的。cubic-bezier(x1, y1, x2, y2) 为自定义，x1,x2,y1,y2的值范围在[0, 1];
在CSS3中，常用的几个动画效果，用cubic-bezier表示分别为：
ease: cubic-bezier(0.25, 0.1, 0.25, 1.0) linear: cubic-bezier(0.0, 0.0, 1.0, 1.0) ease-in: cubic-bezier(0.42, 0, 1.0, 1.0) ease-out: cubic-bezier(0, 0, 0.58, 1.0) ease-in-out: cubic-bezier(0.42, 0, 0.58, 1.0)
CSS3中，动画属性为transition，常用动画如下：
.demo2{
top: 100px;
-webkit-transition: all 600ms cubic-bezier(0.47, 0, 0.745, 0.715);
transition: all 600ms cubic-bezier(0.47, 0, 0.745, 0.715);
}
代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>转盘抽奖</title>
<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="IE=edeg">
<!-- 浏览器兼容版本 -->
<style>
* {
margin: 0;
padding: 0;
}
div{
}
.rotate_con {
margin: 50px auto;
320px;
height: 320px;
}
.rotate_row {
display: flex;
display: -webkit-flex;
height: 33.3333333%;
}
.rotate_item {
flex: 0 0 33.3333333%;
-webkit-flex: 0 0 33.3333333%;
line-height: 106.666666px;
text-align: center;
background: yellow;
padding: 1px;
border: 1px solid #fff;
box-sizing: border-box;
}
.item_start {
position: relative;
background-color: #FF5E5E;
color: #FFFFFF;
font-weight: bold;
cursor: pointer;
border-radius: 50%;
}
.item_start:active {
background: #ED745B;
}
.rotate {
position: absolute;
5px;
height: 106px;
top: -53px;
left: 53px;
background: yellowgreen;
transform: rotateZ(0deg);
transform-origin: left bottom;
-webkit-transform-origin: left bottom;
transition: all 1.5s cubic-bezier(0.25, 0.1, 0.25, 1);
}
.item_active {
border-color: red;
}
</style>
</head>
<body>
<div class="rotate_con">
<div class="rotate_row">
<div class="rotate_item">
RMB100
</div>
<div class="rotate_item">
流量100M
</div>
<div class="rotate_item">
谢谢参与
</div>
</div>
<div class="rotate_row">
<div class="rotate_item">
再接再厉
</div>
<div class="rotate_item item_start" id="start">
开始
<div class="rotate" id="rotate_zhen">
</div>
</div>
<div class="rotate_item">
RMB2
</div>
</div>
<div class="rotate_row">
<div class="rotate_item">
RMB100
</div>
<div class="rotate_item">
谢谢参与
</div>
<div class="rotate_item">
流量100M
</div>
</div>
</div>
<script>
//获取对象
var getid = function(id) {
return document.getElementById(id);
};
//按照旋转顺序的数组
var context = ["流量100M", "谢谢参与", "RMB2", "流量100M", "谢谢参与", "RMB100", "再接再厉", "RMB100"];
var deg = 45, //旋转的默认角度360/8
numdeg = 0, //记录上次旋转停止时候的角度
num = 0, //记录旋转后数组的位置
isRotated = false; //判断是否在进行中
window.onload = function() {
var zhen = getid("rotate_zhen");
getid("start").addEventListener('click', function() {
if(isRotated) return; //如果正在旋转退出程序
isRotated = true;
var index = Math.floor(Math.random() * 8); //得到0-7随机数
num = index + num; //得到本次位置
numdeg += index * deg + Math.floor(Math.random() * 3 + 1) * 360;
zhen.style.webkitTransform = zhen.style.transform = "rotateZ(" + numdeg + "deg)";
setTimeout(function() {
if(num >= 8) { //如果数组位置大于7就重新开始
num = num % 8;
}
alert(context[num]);
isRotated = false; //旋转改为false说明没有旋转
}, 1700)
}, false)
}
</script>
</body>
</html>
素材链接： 链接：https://pan.baidu.com/s/1W_PVCQkZTWMx3M_KrrfPhQ 密码：1nwq