<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<style>
* {
margin: 0;
padding: 0;
}
html,
body {
width: 100%;
height: 100%;
}
div {
width: 100%;
height: 100%;
background: #000;
}
.home_bg {
position: fixed;
left: 0;
right: 0;
top: 0;
bottom: 0;
z-index: 0;
}
</style>
<body>
<div>
<canvas id="canvas-bg"></canvas>
</div>
<script>
const drawBg = () => {
const canvas = document.getElementById('canvas-bg')
if (canvas === null) return
const ctx = canvas?.getContext('2d')
ctx.canvas.width = window.innerWidth
ctx.canvas.height = window.innerHeight
const cW = canvas.width
const cH = canvas.height
const stars = []
// add star with random position
function addStar() {
const x = Math.floor(Math.random() * cW) + -200
const y = Math.floor(Math.random() * cH) + 1
const s = Math.floor(Math.random() * 12) + 1
stars.push({ x: x, y: y, s: s })
}
function starField() {
addStar()
for (let i = 0; i < stars.length; i++) {
ctx.fillStyle = 'rgba(255, 255, 255, 1)'
ctx.fillRect(stars[i].x++, stars[i].y, stars[i].s * 0.15, stars[i].s * 0.15)
ctx.fill()
if (stars[i].x > cW) {
stars.splice(i, 1)
}
}
}
// animate
function animate() {
ctx.save()
ctx.clearRect(0, 0, cW, cH)
starField()
ctx.restore()
}
const animateInterval = setInterval(animate, 50)
}
window.onload = () => {
drawBg()
}
</script>
</body>
</html>
标签：canvas,const,random,ctx,stars,Math From： https://www.cnblogs.com/conlin/p/18025599