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fireworks.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>烟花</title>
<style>
*{
margin: 0;
padding: 0;
}
html,body{
width: 100%;
height: 100%;
}
body{
position: relative;
margin: 0 auto;
}
canvas{
width: 100%;
height: 100%;
position: absolute;
left: 0;
top: 0;
}
#bg{
z-index: 5;
}
#firework{
z-index: 8;
}
</style>
</head>
<body>
<canvas id="bg" width="360" height="600"></canvas>
<canvas id="firework" width="360" height="600"></canvas>
<script>
// 全局配置
const config = {
width: 360,
height: 600,
canvases: ['bg','firework'],
skyColor: 'hsla({hue}, 60%, {lightness}%, 0.2)',
fireworkTime: {min: 30, max: 60},
fireworkOpt: {
x: undefined,
y: undefined,
xEnd: undefined,
yEnd: undefined,
count: 300,
wait: undefined
}
};
// 粒子
class Particle{
constructor({x,y,size = 1,radius = 1.2} = {}){
this.x = x;
this.y = y;
this.size = size;
this.rate = Math.random(); //速度
this.angle = Math.PI * 2 * Math.random(); // 角度
// 粒子横向和纵向的速度
this.vx = radius * Math.cos(this.angle) * this.rate;
this.vy = radius * Math.sin(this.angle) * this.rate;
}
go(){
this.x += this.vx;
this.y += this.vy;
this.vy += 0.02; // 重力加速度
// 空气阻力
this.vx *= 0.98;
this.vy *= 0.98;
}
// 渲染粒子
render(ctx){
this.go();
ctx.beginPath();
ctx.arc(this.x,this.y,this.size,0,Math.PI * 2, false);
ctx.fill();
}
}
// 烟花
class Fireworks{
constructor({x,y = config.height,xEnd,yEnd,count = 300,wait} = {}){
this.x = x || config.width / 8 + Math.random() * config.width * 3 / 4;
this.y = y;
this.xEnd = xEnd || this.x;
this.yEnd = yEnd || config.width / 8 + Math.random() * config.width * 3 / 8;
this.size = 2;
this.velocity = -3;
this.opacity = 0.8;
this.hue = 360 * Math.random() | 0;
this.color = `hsla(${this.hue},80%,60%,1)`;
this.wait = wait || 30 + Math.random() * 30;
// 微粒个数
this.count = count;
this.particles = [];
this.createParticles();
this.status = 1;
}
// 创建微粒
createParticles(){
for(let i = 0; i < this.count; i++){
this.particles.push(new Particle({x:this.xEnd, y: this.yEnd}))
}
}
getSkyColor(){
const skyColor = {
lightness: this.status == 3 ? this.opacity : 0,
hue: this.hue
};
return skyColor;
}
// 升空
rise(){
this.y += this.velocity * 1;
this.velocity += 0.005; // 升空阻力
// 烟花到达目标位置开始渐隐
if(this.y - this.yEnd <= 50){
this.opacity = (this.y - this.yEnd) / 50;
}
// 到达目标位置，开始第二个状态
if(this.y <= this.yEnd){
this.status = 2;
}
}
// 渲染烟花 完成后返回false
render(ctx){
switch(this.status){
case 1: // 升空
ctx.save();
ctx.beginPath();
ctx.globalCompositeOperation = 'lighter';
ctx.globalAlpha = this.opacity;
ctx.translate(this.x, this.y);
ctx.scale(0.8,2.5); // 拉伸 小尾巴长度这里控制
ctx.translate(-this.x,-this.y);
ctx.fillStyle = this.color;
ctx.arc(this.x + Math.sin(Math.PI * 2 * Math.random()) / 1.2, this.y,this.size, 0,Math.PI*2,false);
ctx.fill();
ctx.restore();
this.rise();
return true;
break;
case 2: // 烟花消失 等待爆炸
if(--this.wait <= 0){
this.opacity = 1;
this.status = 3;
}
return true;
break;
case 3: // 爆炸 渲染烟花
ctx.save();
ctx.globalCompositeOperation = 'lighter';
ctx.globalAlpha = this.opacity;
ctx.fillStyle = this.color;
for(let i = 0; i < this.particles.length; ++i){
this.particles[i].render(ctx)
}
ctx.restore();
this.opacity -= 0.01;
return this.opacity > 0;
break;
default:
return false;
}
}
}
// 放烟花
const canvas = {
init: function(){
this.setProperty();
this.renderBg();
this.loop();
},
setProperty: function(){
this.fireworks = [];
this.width = config.width;
this.height = config.height;
this.fireworkTime = (config.fireworkTime.min + (config.fireworkTime.max - config.fireworkTime.min) * Math.random()) | 0;
this.bgCtx = document.querySelector('#bg').getContext('2d');
this.fireworkCtx = document.querySelector('#firework').getContext('2d');
},
renderBg(){
this.bgCtx.fillStyle = 'hsla(210,60%,5%,0.9)';
this.bgCtx.fillRect(0,0,this.width,this.height);
},
loop(){
requestAnimationFrame(this.loop.bind(this));
// this.fireworkCtx.clearRect(0,0,this.width,this.height);
// this.fireworkCtx.fillStyle = config.skyColor;
this.skyColor = {
lightness: 0,
hue: 210
};
this.fireworkCtx.fillStyle = config.skyColor.replace('{lightness}', 5 + this.skyColor.lightness * 15).replace('{hue}' , this.skyColor.hue);
this.fireworkCtx.fillRect(0,0,this.width,this.height);
if(--this.fireworkTime <= 0){
this.fireworks.push(new Fireworks(config.fireworkOpt));
this.fireworkTime = (config.fireworkTime.min + (config.fireworkTime.max - config.fireworkTime.min) * Math.random()) | 0;
}
for(let i = this.fireworks.length - 1; i >= 0; --i){
this.skyColor = this.skyColor.lightness >= this.fireworks[i].getSkyColor().lightness ? this.skyColor : this.fireworks[i].getSkyColor();
!this.fireworks[i].render(this.fireworkCtx) && this.fireworks.splice(i,1);
}
}
}
canvas.init();
</script>
</body>
</html>