效果图:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>流星雨</title>
<style>
canvas {
width: 100%;
height: 100%;
position: absolute;
top: 0;
left: 0;
z-index: -1;
background-image: url("img/12.png");
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
const width = canvas.width = window