CSS3效果：5种预载动画效果
实现如图所示的动画效果：
预载动画一：双旋圈
在两个不同方向旋转的圆圈。我们对内圈的转速定义了一个CSS代码，即内圈比外圈的速率快2倍。
实现如图所示：
html代码：
<body style="background: #ffb83c;"> <div id="preloader-1"> <span></span> <span></span> </div> </body>
css代码：
#preloader-1{ position: relative; } #preloader-1 span{ position: absolute; border:8px solid #fff; border-top:8px solid transparent; border-radius: 999px; } #preloader-1 span:nth-child(1){ width:80px; height: 80px; animation: spin-1 2s infinite linear; } #preloader-1 span:nth-child(2){ top:20px; left:20px; width:40px; height: 40px; animation: spin-2 1s infinite linear; } @keyframes spin-1{ 0%{transform: rotate(360deg); opacity: 1.0;} 50%{transform: rotate(180deg); opacity: 0.5;} 100%{transform: rotate(0deg);opacity: 0;} } @keyframes spin-2{ 0%{transform: rotate(0deg); opacity: 0.5;} 50%{transform: rotate(180deg); opacity: 1;} 100%{transform: rotate(360deg);opacity: 0.5;} }
预载动画二：交错圈
两个圆圈进行横向交错来回移动。每个圆圈都设置了单独的反向移动动画参数。
效果：
html代码：
<body style="background: #4ad3b4;"> <div id="preloader-2"> <span></span> <span></span> </div> </body>
css代码：
#preloader-2{ position: relative; } #preloader-2 span{ position: absolute; width:30px; height: 30px; background: #fff; border-radius: 999px; } #preloader-2 span:nth-child(1){ animation: cross-1 1.5s infinite linear; } #preloader-2 span:nth-child(2){ animation: cross-2 1.5s infinite linear; } @keyframes cross-1{ 0%{transform: translateX(0); opacity: 0.5;} 50%{transform: translateX(80px); opacity: 1;} 100%{transform: translateX(0);opacity: 0.5;} } @keyframes cross-2{ 0%{transform: translateX(80px); opacity: 0.5;} 50%{transform: translateX(0); opacity: 1;} 100%{transform: translateX(80px);opacity: 0.5;} }
预载动画三：旋转圈
效果：
html代码：
<body style="background: #ab69d9;"> <div id="preloader-3"> <span></span> </div> </body>
css代码：
#preloader-3{ position: relative; width:80px; height: 80px; border:4px solid rgba(255,255,255,.25); border-radius: 999px; } #preloader-3 span{ position: absolute; width:80px; height:80px; border:4px solid transparent; border-top:4px solid #fff; border-radius: 999px; top:-4px; left:-4px; animation: rotate 1s infinite linear; } @keyframes rotate{ 0%{transform: rotate(0deg);} 100%{transform: rotate(360deg);} }
预载动画四：跳动圈
这是一种墨西哥波浪纹的动画效果，通过设置不同圆圈之间的延迟参数来实现。
效果：
html代码：
<body style="background: #c1d64a;"> <div id="preloader-4"> <span></span> <span></span> <span></span> <span></span> <span></span> </div> </body>
css代码：
#preloader-4{ position: relative; } #preloader-4 span{ position:absolute; width:16px; height: 16px; border-radius: 999px; background: #fff; animation: bounce 1s infinite linear; } #preloader-4 span:nth-child(1){ left:0; animation-delay: 0s; } #preloader-4 span:nth-child(2){ left:20px; animation-delay: 0.25s; } #preloader-4 span:nth-child(3){ left:40px; animation-delay: 0.5s; } #preloader-4 span:nth-child(4){ left:60px; animation-delay: 0.75s; } #preloader-4 span:nth-child(5){ left:80px; animation-delay: 1.0s; } @keyframes bounce{ 0%{transform: translateY(0px);opacity: 0.5;} 50%{transform: translateY(-30px);opacity: 1.0;} 100%{transform: translateY(0px);opacity: 0.5;} }
预载动画五：雷达圈
一种雷达辐射效果，给3个span elements设置相同的淡入淡出效果，再予每个稍微延迟下即可实现。
效果：
html代码：
<body style="background: #f9553f;"> <div id="preloader-5"> <span></span> <span></span> <span></span> </div> </body>
css代码：
#preloader-5{ position: relative; } #preloader-5 span{ position:absolute; width:50px; height: 50px; border:5px solid #fff; border-radius: 999px; opacity: 0; animation: radar 2s infinite linear; } #preloader-5 span:nth-child(1){ animation-delay: 0s; } #preloader-5 span:nth-child(2){ animation-delay: 0.66s; } #preloader-5 span:nth-child(3){ animation-delay: 1.33s; } @keyframes radar{ 0%{transform: scale(0);opacity: 0;} 25%{transform: scale(0);opacity: 0.5;} 50%{transform: scale(1);opacity: 1.0;} 75%{transform: scale(1.5);opacity: 0.5;} 100%{transform: scale(2);opacity: 0;} }
