下雪js代码

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>下雪效果</title>
<style>
  body {
    margin: 0;
    overflow: hidden;
  }
  canvas {
    display: block;
  }
</style>
</head>
<body>
<canvas id="snowCanvas"></canvas>
<script src="snow.js"></script>
</body>
</html>

// 获取canvas元素和绘图上下文
const canvas = document.getElementById('snowCanvas');
const ctx = canvas.getContext('2d');

// 设置canvas尺寸为窗口大小
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

// 定义雪花对象
class Snowflake {
  constructor() {
    this.x = Math.random() * canvas.width;
    this.y = Math.random() * canvas.height;
    this.size = Math.random() * 3 + 1;
    this.speedX = Math.random() * 3 - 1.5;
    this.speedY = Math.random() * 2 + 1;
  }

  update() {
    this.x += this.speedX;
    this.y += this.speedY;
    if (this.y > canvas.height) {
      this.y = -10;
      this.x = Math.random() * canvas.width;
    }
  }

  draw() {
    ctx.beginPath();
    ctx.arc(this.x, this.y, this.size, 0, Math.PI * 2);
    ctx.fillStyle = '#fff';
    ctx.fill();
  }
}

// 创建雪花数组
const snowflakes = [];
for (let i = 0; i < 500; i++) {
  snowflakes.push(new Snowflake());
}

// 动画循环
function animate() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  for (const snowflake of snowflakes) {
    snowflake.update();
    snowflake.draw();
  }
  requestAnimationFrame(animate);
}

// 开始动画
animate();

// 窗口大小改变时更新canvas尺寸
window.addEventListener('resize', () => {
  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;
});