怎样用canvas特性制作html5烟花的效果

发布网友发布时间：2022-04-28 15:47
共2个回答
懂视网时间：2022-05-12 04:49
这是一个款绚丽的HTML5 Canvas动画，它将模拟的是我们生活中烟花绽放的动画特效，效果非常逼真，下面我们来简单分析一下实现这款HTML5烟花特效的过程及代码，感兴趣的小伙伴们可以参考一下
本文为大家带来了一款，免费而又安全环保的HTML5 Canvas实现的放烟花特效。
效果如下：
代码如下：
<!DOCTYPE HTML>
<html>
 <head>
 <title>Canvas 实现放烟花特效</title>
 <meta charset="utf-8">
 <meta http-equiv="X-UA-Compatible" content="IE=edge">
 <meta name="viewport" content="width=device-width,height=device-height,inital-scale=1.0,maximum-scale=1.0,user-scalable=no">
 <style type="text/css">
 html,body{height:100%;margin:0;padding:0} 
 ul,li{text-indent:0;text-decoration:none;margin:0;padding:0} 
 img{border:0} 
 body{background-color:#000;color:#999;font:100%/18px helvetica, arial, sans-serif} 
 canvas{cursor:crosshair;display:block;left:0;position:absolute;top:0;z-index:20} 
 #header img{width:100%; height:20%;} 
 #bg img{width:100%; height:80%;} 
 #header,#bg{position:fixed;left:0;right:0;z-index:10} 
 #header{top:0} 
 #bg{position:fixed;z-index:1;bottom:0} 
 audio{position:fixed;display:none;bottom:0;left:0;right:0;width:100%;z-index:5} 
 </style>
 </head>
 <body>
 <p id="bg">
 <img id="bgimg" src="http://img.ivsky.com/img/tupian/pre/201508/02/yuzhou_xingkong_yu_yueliang-006.jpg">
 </p>
 <script src="http://cdn.bootcss.com/jquery/2.2.0/jquery.min.js"></script>
 <script>
 $(function(){ 
 var Fireworks = function(){ 
 var self = this; 
 // 产生烟花随机数 
 var rand = function(rMi, rMa){ 
 //按位取反运算符 
 return ~~((Math.random()*(rMa-rMi+1))+rMi); 
 },hitTest = function(x1, y1, w1, h1, x2, y2, w2, h2){ 
 return !(x1 + w1 < x2 || x2 + w2 < x1 || y1 + h1 < y2 || y2 + h2 < y1); 
 }; 
 //请求动画帧 
 window.requestAnimFrame=function(){ 
 return window.requestAnimationFrame 
 ||window.webkitRequestAnimationFrame 
 ||window.mozRequestAnimationFrame 
 ||window.oRequestAnimationFrame 
 ||window.msRequestAnimationFrame 
 ||function(callback){ 
 window.setTimeout(callback,1000/60); 
 } 
 }(); 
 self.init = function(){ 
 self.canvas = document.createElement('canvas'); 
 //canvas 全屏 
 selfself.canvas.width = self.cw = $(window).innerWidth(); 
 selfself.canvas.height = self.ch = $(window).innerHeight(); 
 self.particles = []; 
 self.partCount = 150; 
 self.fireworks = []; 
 selfself.mx = self.cw/2; 
 selfself.my = self.ch/2; 
 self.currentHue = 30; 
 self.partSpeed = 5; 
 self.partSpeedVariance = 10; 
 self.partWind = 50; 
 self.partFriction = 5; 
 self.partGravity = 1; 
 self.hueMin = 0; 
 self.hueMax = 360; 
 self.fworkSpeed = 4; 
 self.fworkAccel = 10; 
 self.hueVariance = 30; 
 self.flickerDensity = 25; 
 self.showShockwave = true; 
 self.showTarget = false; 
 self.clearAlpha = 25; 
 $(document.body).append(self.canvas); 
 selfself.ctx = self.canvas.getContext('2d'); 
 self.ctx.lineCap = 'round'; 
 self.ctx.lineJoin = 'round'; 
 self.lineWidth = 1; 
 self.bindEvents(); 
 self.canvasLoop(); 
 self.canvas.onselectstart = function() { 
 return false; 
 }; 
 }; 
 // 创建粒子 
 self.createParticles = function(x,y, hue){ 
 var countdown = self.partCount; 
 while(countdown--){ 
 var newParticle = { 
 x: x, 
 y: y, 
 coordLast: [ 
 {x: x, y: y}, 
 {x: x, y: y}, 
 {x: x, y: y} 
 ], 
 angle: rand(0, 360), 
 speed: rand(((self.partSpeed - self.partSpeedVariance) <= 0) ? 1 : self.partSpeed - self.partSpeedVariance, (self.partSpeed + self.partSpeedVariance)), 
 friction: 1 - self.partFriction/100, 
 gravity: self.partGravity/2, 
 hue: rand(hue-self.hueVariance, hue+self.hueVariance), 
 brightness: rand(50, 80), 
 alpha: rand(40,100)/100, 
 decay: rand(10, 50)/1000, 
 wind: (rand(0, self.partWind) - (self.partWind/2))/25, 
 lineWidth: self.lineWidth 
 }; 
 self.particles.push(newParticle); 
 } 
 }; 
 // 更新粒子 
 self.updateParticles = function(){ 
 var i = self.particles.length; 
 while(i--){ 
 var p = self.particles[i]; 
 var radians = p.angle * Math.PI / 180; 
 var vx = Math.cos(radians) * p.speed; 
 var vy = Math.sin(radians) * p.speed; 
 p.speed *= p.friction; 
 p.coordLast[2].x = p.coordLast[1].x; 
 p.coordLast[2].y = p.coordLast[1].y; 
 p.coordLast[1].x = p.coordLast[0].x; 
 p.coordLast[1].y = p.coordLast[0].y; 
 p.coordLast[0].x = p.x; 
 p.coordLast[0].y = p.y; 
 p.x += vx; 
 p.y += vy; 
 p.y += p.gravity; 
 p.angle += p.wind; 
 p.alpha -= p.decay; 
 if(!hitTest(0,0,self.cw,self.ch,p.x-p.radius, p.y-p.radius, p.radius*2, p.radius*2) || p.alpha < .05){ 
 self.particles.splice(i, 1); 
 } 
 }; 
 }; 
 // 绘制粒子 
 self.drawParticles = function(){ 
 var i = self.particles.length; 
 while(i--){ 
 var p = self.particles[i];  
 var coordRand = (rand(1,3)-1); 
 self.ctx.beginPath();  
 self.ctx.moveTo(Math.round(p.coordLast[coordRand].x), Math.round(p.coordLast[coordRand].y)); 
 self.ctx.lineTo(Math.round(p.x), Math.round(p.y)); 
 self.ctx.closePath(); 
 self.ctx.strokeStyle = 'hsla('+p.hue+', 100%, '+p.brightness+'%, '+p.alpha+')'; 
 self.ctx.stroke(); 
 if(self.flickerDensity > 0){ 
 var inverseDensity = 50 - self.flickerDensity; 
 if(rand(0, inverseDensity) === inverseDensity){ 
 self.ctx.beginPath(); 
 self.ctx.arc(Math.round(p.x), Math.round(p.y), rand(p.lineWidth,p.lineWidth+3)/2, 0, Math.PI*2, false) 
 self.ctx.closePath(); 
 var randrandAlpha = rand(50,100)/100; 
 self.ctx.fillStyle = 'hsla('+p.hue+', 100%, '+p.brightness+'%, '+randAlpha+')'; 
 self.ctx.fill(); 
 } 
 } 
 }; 
 }; 
 // 创建烟花 
 self.createFireworks = function(startX, startY, targetX, targetY){ 
 var newFirework = { 
 x: startX, 
 y: startY, 
 startX: startX, 
 startY: startY, 
 hitX: false, 
 hitY: false, 
 coordLast: [ 
 {x: startX, y: startY}, 
 {x: startX, y: startY}, 
 {x: startX, y: startY} 
 ], 
 targetX: targetX, 
 targetY: targetY, 
 speed: self.fworkSpeed, 
 angle: Math.atan2(targetY - startY, targetX - startX), 
 shockwaveAngle: Math.atan2(targetY - startY, targetX - startX)+(90*(Math.PI/180)), 
 acceleration: self.fworkAccel/100, 
 hue: self.currentHue, 
 brightness: rand(50, 80), 
 alpha: rand(50,100)/100, 
 lineWidth: self.lineWidth 
 }; 
 self.fireworks.push(newFirework); 
 }; 
 // 更新烟花 
 self.updateFireworks = function(){ 
 var i = self.fireworks.length; 
 while(i--){ 
 var f = self.fireworks[i]; 
 self.ctx.lineWidth = f.lineWidth; 
 vx = Math.cos(f.angle) * f.speed, 
 vy = Math.sin(f.angle) * f.speed; 
 f.speed *= 1 + f.acceleration; 
 f.coordLast[2].x = f.coordLast[1].x; 
 f.coordLast[2].y = f.coordLast[1].y; 
 f.coordLast[1].x = f.coordLast[0].x; 
 f.coordLast[1].y = f.coordLast[0].y; 
 f.coordLast[0].x = f.x; 
 f.coordLast[0].y = f.y; 
 if(f.startX >= f.targetX){ 
 if(f.x + vx <= f.targetX){ 
 ff.x = f.targetX; 
 f.hitX = true; 
 } else { 
 f.x += vx; 
 } 
 } else { 
 if(f.x + vx >= f.targetX){ 
 ff.x = f.targetX; 
 f.hitX = true; 
 } else { 
 f.x += vx; 
 } 
 } 
 if(f.startY >= f.targetY){ 
 if(f.y + vy <= f.targetY){ 
 ff.y = f.targetY; 
 f.hitY = true; 
 } else { 
 f.y += vy; 
 } 
 } else { 
 if(f.y + vy >= f.targetY){ 
 ff.y = f.targetY; 
 f.hitY = true; 
 } else { 
 f.y += vy; 
 } 
 } 
 if(f.hitX && f.hitY){ 
 self.createParticles(f.targetX, f.targetY, f.hue); 
 self.fireworks.splice(i, 1); 
 } 
 }; 
 }; 
 // 绘制烟花 
 self.drawFireworks = function(){ 
 var i = self.fireworks.length; 
 self.ctx.globalCompositeOperation = 'lighter'; 
 while(i--){ 
 var f = self.fireworks[i]; 
 self.ctx.lineWidth = f.lineWidth; 
 var coordRand = (rand(1,3)-1); 
 self.ctx.beginPath();  
 self.ctx.moveTo(Math.round(f.coordLast[coordRand].x), Math.round(f.coordLast[coordRand].y)); 
 self.ctx.lineTo(Math.round(f.x), Math.round(f.y)); 
 self.ctx.closePath(); 
 self.ctx.strokeStyle = 'hsla('+f.hue+', 100%, '+f.brightness+'%, '+f.alpha+')'; 
 self.ctx.stroke(); 
 if(self.showTarget){ 
 self.ctx.save(); 
 self.ctx.beginPath(); 
 self.ctx.arc(Math.round(f.targetX), Math.round(f.targetY), rand(1,8), 0, Math.PI*2, false) 
 self.ctx.closePath(); 
 self.ctx.lineWidth = 1; 
 self.ctx.stroke(); 
 self.ctx.restore(); 
 } 
 if(self.showShockwave){ 
 self.ctx.save(); 
 self.ctx.translate(Math.round(f.x), Math.round(f.y)); 
 self.ctx.rotate(f.shockwaveAngle); 
 self.ctx.beginPath(); 
 self.ctx.arc(0, 0, 1*(f.speed/5), 0, Math.PI, true); 
 self.ctx.strokeStyle = 'hsla('+f.hue+', 100%, '+f.brightness+'%, '+rand(25, 60)/100+')'; 
 self.ctx.lineWidth = f.lineWidth; 
 self.ctx.stroke(); 
 self.ctx.restore(); 
 } 
 }; 
 }; 
 // 绑定事件 
 self.bindEvents = function(){ 
 $(window).on('resize', function(){ 
 clearTimeout(self.timeout); 
 self.timeout = setTimeout(function() { 
 selfself.canvas.width = self.cw = $(window).innerWidth(); 
 selfself.canvas.height = self.ch = $(window).innerHeight(); 
 self.ctx.lineCap = 'round'; 
 self.ctx.lineJoin = 'round'; 
 }, 100); 
 }); 
 $(self.canvas).on('mousedown', function(e){ 
 self.mx = e.pageX - self.canvas.offsetLeft; 
 self.my = e.pageY - self.canvas.offsetTop; 
 self.currentHue = rand(self.hueMin, self.hueMax); 
 self.createFireworks(self.cw/2, self.ch, self.mx, self.my); 
 $(self.canvas).on('mousemove.fireworks', function(e){ 
 self.mx = e.pageX - self.canvas.offsetLeft; 
 self.my = e.pageY - self.canvas.offsetTop; 
 self.currentHue = rand(self.hueMin, self.hueMax); 
 self.createFireworks(self.cw/2, self.ch, self.mx, self.my);  
 }); 
 }); 
 $(self.canvas).on('mouseup', function(e){ 
 $(self.canvas).off('mousemove.fireworks');  
 }); 
 }; 
 self.clear = function(){ 
 self.particles = []; 
 self.fireworks = []; 
 self.ctx.clearRect(0, 0, self.cw, self.ch); 
 }; 
 self.canvasLoop = function(){ 
 requestAnimFrame(self.canvasLoop, self.canvas); 
 self.ctx.globalCompositeOperation = 'destination-out'; 
 self.ctx.fillStyle = 'rgba(0,0,0,'+self.clearAlpha/100+')'; 
 self.ctx.fillRect(0,0,self.cw,self.ch); 
 self.updateFireworks(); 
 self.updateParticles(); 
 self.drawFireworks(); 
 self.drawParticles(); 
 }; 
 self.init(); 
 } 
 var fworks = new Fireworks(); 
 $('#info-toggle').on('click', function(e){ 
 $('#info-inner').stop(false, true).slideToggle(100); 
 e.preventDefault(); 
 }); 
 }); 
 </script>
 <canvas width="1400" height="449"></canvas>
 </body>
</html>
是不是被HTML5强大的效果惊呆了，一饱眼福了吧。
热心网友时间：2022-05-12 01:57
1、熟悉canvas的API
2、知道怎么制作烟花效果
上边两条都会了就会做了。
或者，找个别人写的源码看看。前提是你要看得懂。

烟花属于粒子效果。
就是大量的小圆点，按照一定的规律运动，然后消失。有的可能会用到滤镜。