今天在网上看到一个国外写的CSS3 3D Bouncing Ball(3D反弹球)，很有意思，并且实现起来也不难，于是忍不住自己也试写一遍。

好玩的东西当然要大家一起分享，所以接下来我就简单讲解一下如何实现跳动的效果

首先讲解一下结构，wrap是用来控制小球跳动的区域，ball就是小球啦，ballshadow是用来制作小球的投影，因为小球的运动和投影部分的运动(动画)效果是分开的，所以小球和投影部分要两个div来组成，而wrap设置的高度即为小球运动的高度，此时我们就可以通过top属性来很好的控制小球的位置变化。

小球运动区域CSS

.wrap {

width: 150px;

height: 300px;

position: absolute;

left: 50%;

top: 50%;

margin: -150px 0 0 -75px;

}

小球的CSS

通过渐变和投影来制作小球的立体感

.ball {

width: 100px;

height: 100px;

border-radius: 50%;

background: rgb(187,187,187);

background: url(data:image/svg+xml;base64,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);

background: -moz-linear-gradient(top, rgba(187,187,187,1) 0%, rgba(119,119,119,1) 99%);

background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(187,187,187,1)), color-stop(99%,rgba(119,119,119,1)));

background: -webkit-linear-gradient(top, rgba(187,187,187,1) 0%,rgba(119,119,119,1) 99%);

background: -o-linear-gradient(top, rgba(187,187,187,1) 0%,rgba(119,119,119,1) 99%);

background: -ms-linear-gradient(top, rgba(187,187,187,1) 0%,rgba(119,119,119,1) 99%);

background: linear-gradient(top, rgba(187,187,187,1) 0%,rgba(119,119,119,1) 99%);

filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#bbbbbb', endColorstr='#777777',GradientType=0 );

box-shadow: inset 0 -5px 15px rgba(255,255,255,0.4),

inset -2px -1px 40px rgba(0,0,0,0.4),

0 0 1px #000;

position: absolute;

z-index: 99;

}

小球反光面的CSS

利用after伪类来实现，通过渐变和圆角属性来实现半透明椭圆形遮罩

.ball::after {

content: "";

width: 60px;

height: 30px;

position: absolute;

left: 20px;

top: 10px;

z-index: 10;

background: url(data:image/svg+xml;base64,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);

background: -moz-linear-gradient(top, rgba(232,232,232,1) 0%, rgba(232,232,232,1) 1%, rgba(255,255,255,0) 100%);

background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(232,232,232,1)), color-stop(1%,rgba(232,232,232,1)), color-stop(100%,rgba(255,255,255,0)));

background: -webkit-linear-gradient(top, rgba(232,232,232,1) 0%,rgba(232,232,232,1) 1%,rgba(255,255,255,0) 100%);

background: -o-linear-gradient(top, rgba(232,232,232,1) 0%,rgba(232,232,232,1) 1%,rgba(255,255,255,0) 100%);

background: -ms-linear-gradient(top, rgba(232,232,232,1) 0%,rgba(232,232,232,1) 1%,rgba(255,255,255,0) 100%);

background: linear-gradient(top, rgba(232,232,232,1) 0%,rgba(232,232,232,1) 1%,rgba(255,255,255,0) 100%);

filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#e8e8e8', endColorstr='#00ffffff',GradientType=0 );

border-radius: 40px / 20px;

}

投影部分的CSS

利用半透明的背景和模糊滤镜来制作投影效果

.ballshadow {

width: 100px;

height: 50px;

border-radius: 50%;

background: rgba(0,0,0,0.3);

position: absolute;

filter: url(blur.svg#blur); /* FireFox, Chrome, Opera */

-webkit-filter: blur(10px); /* Chrome, Opera */

-moz-filter: blur(10px);

-ms-filter: blur(10px);

filter: blur(10px);

filter: progid:DXImageTransform.Microsoft.Blur(PixelRadius=10, MakeShadow=false); /* IE6~IE9 */

bottom: 0;

}

这样就完成了整个画布的布局，接下来我们要为他增加动画效果，首先是小球的运动

这里只贴出一个兼容-webkit-的写法，通过scale(缩放)来使当小球产生一种反弹挤压的效果，原作中是通过控制border-radius的变化来产生挤压效果，感觉不太好计算，倒不如缩放来的爽快。

同时有一点要注意，当小球的top等于wrap的高度减去小球自身的高度时就是小球碰撞到底部的位置了。

@-webkit-keyframes bounce {

0% {top: 0;

-webkit-animation-timing-function: ease-in;

}

40% {}

50% {

top: 180px;

-webkit-animation-timing-function: ease-out;

-webkit-transform:scale(1);

}

55% {

top: 200px;

-webkit-transform:scale(1, 0.65);

-webkit-animation-timing-function: ease-in;

}

65% {

top: 160px;

-webkit-transform:scale(1);

-webkit-animation-timing-function: ease-out;}

95% {

top: 0;

-webkit-animation-timing-function: ease-in;

}

100% {

top: 0;

-webkit-animation-timing-function: ease-in;

}

}

投影部分的动画：

投影部分的动画再简单不过了，原作中同样是使用border-radius来控制一个缩放的效果，这里我们直接使用scale，并且配合动画的速度曲线属性来迎合跳动小球变化

@-webkit-keyframes shrink {

0% {

-webkit-transform:scale(1);

-webkit-animation-timing-function: ease-in;

}

50% {

-webkit-transform:scale(0.7);

-webkit-animation-timing-function: ease-out;

}

100% {

-webkit-transform:(1);

-webkit-animation-timing-function: ease-in;

}

}

接着我们为元素添加上相应的动画就OK了

.ball {

animation: bounce 1s infinite linear;

-webkit-animation: bounce 1s infinite linear;

-moz-animation: bounce 1s infinite linear;

-o-animation: bounce 1s infinite linear;

}

.ballshadow {

-webkit-animation: shrink 1s infinite linear;

-moz-animation: shrink 1s infinite linear;

animation: shrink 1s infinite linear;

-o-animation: shrink 1s infinite linear;

}

那么该如何实现点击hold住的时候让小球越跳越远？其实这只是利用了一个视觉效果，让整个wrap缩放，由1至0就会产生这样的效果，这里的实现方式就不说了，有兴趣的话大家自己尝试一下，利用active伪类就可以实现按下hold出现的状态。