canvas下雨打雷效果
废话不多说，代码走起
*html部分*
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<title>canvas下雨打雷效果</title>
<link rel="stylesheet" href="css/style.css">
</head>
<body onresize="_pexresize()">
<canvas id="dowebok" width="1280" height="720"></canvas>
<script src="js/script.js"></script>
</body>
</html>
body {
margin: 0;
background: #000;
}
canvas {
background: url("../images/img1.jpg");
background-size: cover;
background-repeat: no-repeat;
background-position: center center;
}
*javascript部分*
var canvas = document.getElementById('dowebok');
var ctx = canvas.getContext('2d');
var stgw = 1280;
var stgh = 720;
var loffset = 0;
var toffset = 0;
function _pexresize() {
var cw = window.innerWidth;
var ch = window.innerHeight;
if (cw <= ch * stgw / stgh) {
loffset = 0;
toffset = Math.floor(ch - (cw * stgh / stgw)) / 2;
canvas.style.width = cw + "px";
canvas.style.height = Math.floor(cw * stgh / stgw) + "px";
} else {
loffset = Math.floor(cw - (ch * stgw / stgh)) / 2;
toffset = 0;
canvas.style.height = ch + "px";
canvas.style.width = Math.floor(ch * stgw / stgh) + "px";
}
canvas.style.marginLeft = loffset + "px";
canvas.style.marginTop = toffset + "px";
}
_pexresize();
var count = 100;
var lcount = 6;
var layer = [];
var layery = [];
ctx.fillStyle = "rgba(255,255,255,0.5)";
for (var l = 0; l < lcount; l++) {
ctx.clearRect(0, 0, stgw, stgh);
for (var i = 0; i < count * (lcount - l) / 1.5; i++) {
var myx = Math.floor(Math.random() * stgw);
var myy = Math.floor(Math.random() * stgh);
var myh = l * 6 + 8;
var myw = myh / 10;
ctx.beginPath();
ctx.moveTo(myx, myy);
ctx.lineTo(myx + myw, myy + myh);
ctx.arc(myx, myy + myh, myw, 0, 1 * Math.PI);
ctx.lineTo(myx - myw, myy + myh);
ctx.closePath();
ctx.fill();
}
layer[l] = new Image();
layer[l].src = canvas.toDataURL("image/png");
layery[l] = 0;
}
var stt = 0;
var str = Date.now() + Math.random() * 4000;
var stact = false;
function animate() {
ctx.clearRect(0, 0, stgw, stgh);
for (var l = 0; l < lcount; l++) {
layery[l] += (l + 1.5) * 5;
if (layery[l] > stgh) {
layery[l] = layery[l] - stgh;
}
ctx.drawImage(layer[l], 0, layery[l]);
ctx.drawImage(layer[l], 0, layery[l] - stgh);
}
if (Date.now() > str) {
stact = true;
}
if (stact) {
stt++;
if (stt < 5 + Math.random() * 10) {
var ex = stt / 30;
} else {
var ex = (stt - 10) / 30;
}
if (stt > 20) {
stt = 0;
stact = false;
str = Date.now() + Math.random() * 8000 + 2000;
}
ctx.fillStyle = "rgba(255,255,255," + ex + ")";
ctx.fillRect(0, 0, stgw, stgh);
}
window.requestAnimationFrame(animate);
}
animate();
转载：https://blog.csdn.net/m0_46597790/article/details/106758021
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