时间：2021-07-01 10:21:17 帮助过：51人阅读
首先我们来看看效果：
动画的实现原理：
动画使用了两个关键帧（keyframes）：
一个是烟花筒上升的轨迹，另一个是烟花绽放中的火星碎片。在这里你可以看到正在进行的基本草图：
每个烟花筒沿着场地底部的线分配一个随机的起始位置。它还在标记的区域内分配了一个随机目标。当烟花筒接近其目标点时，它会缩小为不可见（0x0像素）。
此时，耀斑变得可见。这些实际上是一系列以径向方式向外指向的DIV，在向外的尖端有一种颜色 - 就像火柴棍一样。为了模拟爆炸，他们只是增加了长度，使灯光向外移动。
JavaScript用于：
1、将所有必需的元素添加到页面（DOM）;
2、为每个烟花筒创建和分配关键帧 ; 和
3、指定颜色并将每个光斑旋转到正确的位置。
代码示例：
html代码：
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>烟花绽放</title> <link rel="stylesheet" type="text/css" href="css-fireworks.css"> </head> <body> <div id="stage"><!-- 动画效果发生在这里 --></div> <script type="text/javascript" src="css-fireworks.js"></script> </body> </html>
css代码（css-fireworks.css）
@-webkit-keyframes explosion {
from {
width: 0;
opacity: 0;
}
33% {
width: 0;
opacity: 0;
}
34% {
width: 10px;
opacity: 1.0;
}
40% {
width: 80px;
opacity: 1.0;
}
to {
width: 90px;
opacity: 0;
}
}
@-moz-keyframes explosion {
from {
width: 0;
opacity: 0;
}
33% {
width: 0;
opacity: 0;
}
34% {
width: 10px;
opacity: 1.0;
}
40% {
width: 80px;
opacity: 1.0;
}
to {
width: 90px;
opacity: 0;
}
}
#stage {
position: relative;
width: 600px;
height: 400px;
margin: 100px auto;
background: #000 url(img/outerspace.jpg);
}
.launcher {
position: absolute;
-webkit-animation-duration: 4s;
-webkit-animation-iteration-count: infinite;
-moz-animation-duration: 4s;
-moz-animation-iteration-count: infinite;
background: red;
border-bottom: 3px solid yellow;
}
.launcher div {
position: absolute;
opacity: 0;
-webkit-animation-name: explosion;
-webkit-animation-duration: 4s;
-webkit-animation-iteration-count: infinite;
-moz-animation-name: explosion;
-moz-animation-duration: 4s;
-moz-animation-iteration-count: infinite;
left: 3px;
top: 3px;
width: 10px;
height: 4px;
border-right: 4px solid yellow;
border-radius: 2px;
-webkit-transform-origin: 0 0;
-moz-transform-origin: 0 0;
}js代码（css-fireworks.js）
document.addEventListener("DOMContentLoaded", function() {
var num_launchers = 12;
var num_flares = 20;
var flare_colours = ['red', 'aqua', 'violet', 'yellow', 'lightgreen', 'white', 'blue'];
var cssIdx = document.styleSheets.length - 1;
function myRandom(from, to)
{
return from + Math.floor(Math.random() * (to-from));
}
var keyframes_template = "from { left: LEFTFROM%; top: 380px; width: 6px; height: 12px; }\n"
+ "33% { left: LEFTTOP%; top: TOPTOPpx; width: 0; height: 0; }\n"
+ " to { left: LEFTEND%; top: BOTBOTpx; width: 0; height: 0; }";
for(var i=0; i < num_launchers; i++) {
leftfrom = myRandom(15, 85);
lefttop = myRandom(30, 70);
toptop = myRandom(20, 200);
leftend = lefttop + (lefttop-leftfrom)/2;
botbot = toptop + 100;
csscode = keyframes_template;
csscode = csscode.replace(/LEFTFROM/, leftfrom);
csscode = csscode.replace(/LEFTTOP/, lefttop);
csscode = csscode.replace(/TOPTOP/, toptop);
csscode = csscode.replace(/LEFTEND/, leftend);
csscode = csscode.replace(/BOTBOT/, botbot);
try { // WebKit browsers
csscode2 = "@-webkit-keyframes flight_" + i + " {\n" + csscode + "\n}";
document.styleSheets[cssIdx].insertRule(csscode2, 0);
} catch(e) { }
try { // Mozilla browsers
csscode2 = "@-moz-keyframes flight_" + i + " {\n" + csscode + "\n}";
document.styleSheets[cssIdx].insertRule(csscode2, 0);
} catch(e) { }
}
for(var i=0; i < num_launchers; i++) {
var rand = myRandom(0, flare_colours.length - 1);
var rand_colour = flare_colours[rand];
var launch_delay = myRandom(0,100) / 10;
csscode = ".launcher:nth-child(" + num_launchers + "n+" + i + ") {\n"
+ " -webkit-animation-name: flight_" + i + ";\n"
+ " -webkit-animation-delay: " + launch_delay + "s;\n"
+ " -moz-animation-name: flight_" + i + ";\n"
+ " -moz-animation-delay: " + launch_delay + "s;\n"
+ "}";
document.styleSheets[cssIdx].insertRule(csscode, 0);
csscode = ".launcher:nth-child(" + num_launchers + "n+" + i + ") div {"
+ " border-color: " + rand_colour + ";\n"
+ " -webkit-animation-delay: " + launch_delay + "s;\n"
+ " -moz-animation-delay: " + launch_delay + "s;\n"
+ "}";
document.styleSheets[cssIdx].insertRule(csscode, 0);
}
for(var i=0; i < num_flares; i++) {
csscode = ".launcher div:nth-child(" + num_flares + "n+" + i + ") {\n"
+ " -webkit-transform: rotate(" + (i * 360/num_flares) + "deg);\n"
+ " -moz-transform: rotate(" + (i * 360/num_flares) + "deg);\n"
+ "}";
document.styleSheets[cssIdx].insertRule(csscode, 0);
}
for(var i=0; i < num_launchers; i++) {
var newdiv = document.createElement("div");
newdiv.className = "launcher";
for(var j=0; j < num_flares; j++) {
newdiv.appendChild(document.createElement("div"));
}
document.getElementById("stage").appendChild(newdiv);
}
}, false);总结：以上就是本篇文的全部内容，大家可以自己动手试试，加深理解。希望能对大家的学习有所帮助，推荐视频学习：css3教程！
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