本文主要是介绍使用js和canvas实现下雪效果，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
需求:
实现较为逼真的下雪效果
实现:
<!-- snow 样式 -->
<style>
body {
display: flex;
justify-content: center;
align-items: center;
gap: 1em;
min-height: 100vh;
background-image: radial-gradient(circle at 50% 100%, #1b1b35, #121225);
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
"Helvetica Neue", "Open Sans", system-ui, sans-serif,
"Apple Color Emoji", "Segoe UI Emoji";
}
.canvas {
position: absolute;
inset: 0;
pointer-events: none;
}
.rotate-container {
display: inline-block;
position: absolute;
z-index: 17;
width: 10rem;
height: 10rem;
left: 50%;
top: 5.8rem;
animation: rotate-container 17s linear infinite;
transform: translateX(-50%);
}
.ball-img {
width: 100%;
height: 100%;
}
.title-img{
display: inline-block;
position: absolute;
z-index: 17;
width: 6rem;
/* height: 2rem; */
left: 50%;
top: 10rem;
transform: translateX(-50%);
}
/* @keyframes rotate-container {
0% {
transform: translateX(-50%) rotate(0deg) scale(1);
}
25% {
transform: translateX(-50%) rotate(90deg) scale(0.8);
}
50% {
transform: translateX(-50%) rotate(180deg) scale(1);
}
75% {
transform: translateX(-50%) rotate(270deg) scale(0.8);
}
100% {
transform: translateX(-50%) rotate(360deg) scale(1);
}
} */
@keyframes rotate-container {
0% {
transform: translateX(-50%) rotate(0deg) scale(1);
}
25% {
transform: translateX(-50%) rotate(90deg) scale(1);
}
50% {
transform: translateX(-50%) rotate(180deg) scale(1);
}
75% {
transform: translateX(-50%) rotate(270deg) scale(1);
}
100% {
transform: translateX(-50%) rotate(360deg) scale(1);
}
}
.T9TB07{
z-index: 17;
}
.zlfwHK{
z-index: 17;
}
<body style="background: #fff;">
<div id="app" id="app" style="background-color: #333;
overflow: hidden;">
<!-- canvas 雪花 -->
<canvas class="canvas" style="display: flex;
z-index: 18;
position: fixed;
"></canvas>
</div>
<!-- 雪花 代码 -->
<script>
const canvas = document.querySelector(".canvas");
const ctx = canvas.getContext("2d");
const pixelRatio = window.devicePixelRatio || 1;
const snowflakes = [];
class Snowflake {
constructor() {
this.x = Math.random() * canvas.width;
this.y = Math.random() * canvas.height;
const maxSize = 3;
this.size = Math.random() * (maxSize - 1) + 1;
this.velocity = this.size * 0.35;
const opacity = this.size / maxSize;
this.fill = `rgb(255 255 255 / ${opacity})`;
this.windSpeed = (Math.random() - 0.5) * 0.1;
this.windAngle = Math.random() * Math.PI * 2;
}
isOutsideCanvas() {
return this.y > canvas.height + this.size;
}
reset() {
this.x = Math.random() * canvas.width;
this.y = -this.size;
}
update() {
this.windAngle += this.windSpeed;
this.wind = Math.cos(this.windAngle) * 0.5;
this.x += this.wind;
this.y += this.velocity;
if (this.isOutsideCanvas()) {
this.reset();
}
}
draw() {
ctx.beginPath();
ctx.arc(this.x, this.y, this.size, 0, Math.PI * 2);
ctx.fillStyle = this.fill;
ctx.fill();
ctx.closePath();
}
}
const createSnowflakes = () => {
// snowflakeCount = Math.floor(
// (window.innerWidth * window.innerHeight) / 1400
// );
snowflakeCount = Math.floor(
(1920*2000) / 1400
);
console.log(snowflakeCount,'snowflakeCount')
for (let i = 0; i < snowflakeCount; i++) {
snowflakes.push(new Snowflake());
}
};
console.log(window.innerWidth,'window.innerWidth-')
console.log(window.innerHeight,'window.innerHeight-')
// 调整canvas大小
const resizeCanvas = () => {
const width = window.innerWidth;
console.log(width,'window.innerWidth')
const height = window.innerHeight;
console.log(pixelRatio,'pixelRatio')
canvas.width = width * pixelRatio;
console.log(canvas.width,'canvas.width')
canvas.height = height * pixelRatio;
canvas.style.width = `${width}px`;
canvas.style.height = `${height}px`;
// 修改
// canvas.style.width = `100%`;
// canvas.style.height = `100%`;
ctx.scale(pixelRatio, pixelRatio);
snowflakes.length = 0;
createSnowflakes();
};
window.addEventListener("resize", resizeCanvas);
resizeCanvas();
const render = () => {
requestAnimationFrame(render);
ctx.clearRect(0, 0, canvas.width, canvas.height);
snowflakes.forEach((snowflake) => {
snowflake.update();
snowflake.draw();
});
};
render();
</script>
</body>
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8" /><meta http-equiv="X-UA-Compatible" content="IE=edge" /><meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" /><!-- snow 样式 --><style>body {display: flex;justify-content: center;align-items: center;gap: 1em;min-height: 100vh;background-image: radial-gradient(circle at 50% 100%, #1b1b35, #121225);font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,"Helvetica Neue", "Open Sans", system-ui, sans-serif,"Apple Color Emoji", "Segoe UI Emoji";}.canvas {position: absolute;inset: 0;pointer-events: none;}.rotate-container {display: inline-block;position: absolute;z-index: 17;width: 10rem;height: 10rem;left: 50%;top: 5.8rem;animation: rotate-container 17s linear infinite;transform: translateX(-50%);}.ball-img {width: 100%;height: 100%;}.title-img{display: inline-block;position: absolute;z-index: 17;width: 6rem;/* height: 2rem; */left: 50%;top: 10rem;transform: translateX(-50%);}@keyframes rotate-container {0% {transform: translateX(-50%) rotate(0deg) scale(1);}25% {transform: translateX(-50%) rotate(90deg) scale(1);}50% {transform: translateX(-50%) rotate(180deg) scale(1);}75% {transform: translateX(-50%) rotate(270deg) scale(1);}100% {transform: translateX(-50%) rotate(360deg) scale(1);}}.T9TB07{z-index: 17;}.zlfwHK{z-index: 17;}</style></head><body style="background: #fff;"><div id="app" id="app" style="background-color: #333;overflow: hidden;"><!-- canvas 雪花 --><canvas class="canvas" style="display: flex;z-index: 18;position: fixed;"></canvas></div><!-- 雪花 代码 --><script>const canvas = document.querySelector(".canvas");const ctx = canvas.getContext("2d");const pixelRatio = window.devicePixelRatio || 1;const snowflakes = [];class Snowflake {constructor() {this.x = Math.random() * canvas.width;this.y = Math.random() * canvas.height;const maxSize = 3;this.size = Math.random() * (maxSize - 1) + 1;this.velocity = this.size * 0.35;const opacity = this.size / maxSize;this.fill = `rgb(255 255 255 / ${opacity})`;this.windSpeed = (Math.random() - 0.5) * 0.1;this.windAngle = Math.random() * Math.PI * 2;}isOutsideCanvas() {return this.y > canvas.height + this.size;}reset() {this.x = Math.random() * canvas.width;this.y = -this.size;}update() {this.windAngle += this.windSpeed;this.wind = Math.cos(this.windAngle) * 0.5;this.x += this.wind;this.y += this.velocity;if (this.isOutsideCanvas()) {this.reset();}}draw() {ctx.beginPath();ctx.arc(this.x, this.y, this.size, 0, Math.PI * 2);ctx.fillStyle = this.fill;ctx.fill();ctx.closePath();}}const createSnowflakes = () => {// snowflakeCount = Math.floor(// (window.innerWidth * window.innerHeight) / 1400// );snowflakeCount = Math.floor((1920*2000) / 1400);console.log(snowflakeCount,'snowflakeCount')for (let i = 0; i < snowflakeCount; i++) {snowflakes.push(new Snowflake());}};console.log(window.innerWidth,'window.innerWidth-')console.log(window.innerHeight,'window.innerHeight-')// 调整canvas大小const resizeCanvas = () => {const width = window.innerWidth;console.log(width,'window.innerWidth')const height = window.innerHeight;console.log(pixelRatio,'pixelRatio')canvas.width = width * pixelRatio;console.log(canvas.width,'canvas.width')canvas.height = height * pixelRatio;canvas.style.width = `${width}px`;canvas.style.height = `${height}px`;// 修改// canvas.style.width = `100%`;// canvas.style.height = `100%`;ctx.scale(pixelRatio, pixelRatio);snowflakes.length = 0;createSnowflakes();};window.addEventListener("resize", resizeCanvas);resizeCanvas();const render = () => {requestAnimationFrame(render);ctx.clearRect(0, 0, canvas.width, canvas.height);snowflakes.forEach((snowflake) => {snowflake.update();snowflake.draw();});};render();</script></body></html>
实现效果:
录屏2023-12-21 11.26.28
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