小编给大家分享一下怎么使用canvas实现烟花特效，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
canvas可以实现不同动画效果，本文主要记录几种不同节日烟花效果实现。
实现一
html
<canvas id="canvas"></canvas>css
body { background: #000; margin: 0;}canvas { cursor: crosshair; display: block;}js
// when animating on canvas, it is best to use requestAnimationFrame instead of setTimeout or setInterval// not supported in all browsers though and sometimes needs a prefix, so we need a shimwindow.requestAnimFrame = (function () { return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function (callback) { window.setTimeout(callback, 1000 / 60); };})();// now we will setup our basic variables for the demovar canvas = document.getElementById('canvas'), ctx = canvas.getContext('2d'), // full screen dimensions cw = window.innerWidth, ch = window.innerHeight, // firework collection fireworks = [], // particle collection particles = [], // starting hue hue = 120, // when launching fireworks with a click, too many get launched at once without a limiter, one launch per 5 loop ticks limiterTotal = 5, limiterTick = 0, // this will time the auto launches of fireworks, one launch per 80 loop ticks timerTotal = 80, timerTick = 0, mousedown = false, // mouse x coordinate, mx, // mouse y coordinate my;// set canvas dimensionscanvas.width = cw;canvas.height = ch;// now we are going to setup our function placeholders for the entire demo// get a random number within a rangefunction random(min, max) { return Math.random() * (max - min) + min;}// calculate the distance between two pointsfunction calculateDistance(p1x, p1y, p2x, p2y) { var xDistance = p1x - p2x, yDistance = p1y - p2y; return Math.sqrt(Math.pow(xDistance, 2) + Math.pow(yDistance, 2));}// create fireworkfunction Firework(sx, sy, tx, ty) { // actual coordinates this.x = sx; this.y = sy; // starting coordinates this.sx = sx; this.sy = sy; // target coordinates this.tx = tx; this.ty = ty; // distance from starting point to target this.distanceToTarget = calculateDistance(sx, sy, tx, ty); this.distanceTraveled = 0; // track the past coordinates of each firework to create a trail effect, increase the coordinate count to create more prominent trails this.coordinates = []; this.coordinateCount = 3; // populate initial coordinate collection with the current coordinates while (this.coordinateCount--) { this.coordinates.push([this.x, this.y]); } this.angle = Math.atan2(ty - sy, tx - sx); this.speed = 2; this.acceleration = 1.05; this.brightness = random(50, 70); // circle target indicator radius this.targetRadius = 1;}// update fireworkFirework.prototype.update = function (index) { // remove last item in coordinates array this.coordinates.pop(); // add current coordinates to the start of the array this.coordinates.unshift([this.x, this.y]); // cycle the circle target indicator radius if (this.targetRadius < 8) { this.targetRadius += 0.3; } else { this.targetRadius = 1; } // speed up the firework this.speed *= this.acceleration; // get the current velocities based on angle and speed var vx = Math.cos(this.angle) * this.speed, vy = Math.sin(this.angle) * this.speed; // how far will the firework have traveled with velocities applied? this.distanceTraveled = calculateDistance(this.sx, this.sy, this.x + vx, this.y + vy); // if the distance traveled, including velocities, is greater than the initial distance to the target, then the target has been reached if (this.distanceTraveled >= this.distanceToTarget) { createParticles(this.tx, this.ty); // remove the firework, use the index passed into the update function to determine which to remove fireworks.splice(index, 1); } else { // target not reached, keep traveling this.x += vx; this.y += vy; }}// draw fireworkFirework.prototype.draw = function () { ctx.beginPath(); // move to the last tracked coordinate in the set, then draw a line to the current x and y ctx.moveTo(this.coordinates[this.coordinates.length - 1][0], this.coordinates[this.coordinates.length - 1][ 1 ]); ctx.lineTo(this.x, this.y); ctx.strokeStyle = 'hsl(' + hue + ', 100%, ' + this.brightness + '%)'; ctx.stroke(); ctx.beginPath(); // draw the target for this firework with a pulsing circle ctx.arc(this.tx, this.ty, this.targetRadius, 0, Math.PI * 2); ctx.stroke();}// create particlefunction Particle(x, y) { this.x = x; this.y = y; // track the past coordinates of each particle to create a trail effect, increase the coordinate count to create more prominent trails this.coordinates = []; this.coordinateCount = 5; while (this.coordinateCount--) { this.coordinates.push([this.x, this.y]); } // set a random angle in all possible directions, in radians this.angle = random(0, Math.PI * 2); this.speed = random(1, 10); // friction will slow the particle down this.friction = 0.95; // gravity will be applied and pull the particle down this.gravity = 1; // set the hue to a random number +-20 of the overall hue variable this.hue = random(hue - 20, hue + 20); this.brightness = random(50, 80); this.alpha = 1; // set how fast the particle fades out this.decay = random(0.015, 0.03);}// update particleParticle.prototype.update = function (index) { // remove last item in coordinates array this.coordinates.pop(); // add current coordinates to the start of the array this.coordinates.unshift([this.x, this.y]); // slow down the particle this.speed *= this.friction; // apply velocity this.x += Math.cos(this.angle) * this.speed; this.y += Math.sin(this.angle) * this.speed + this.gravity; // fade out the particle this.alpha -= this.decay; // remove the particle once the alpha is low enough, based on the passed in index if (this.alpha <= this.decay) { particles.splice(index, 1); }} // draw particleParticle.prototype.draw = function () { ctx.beginPath(); // move to the last tracked coordinates in the set, then draw a line to the current x and y ctx.moveTo(this.coordinates[this.coordinates.length - 1][0], this.coordinates[this.coordinates.length - 1][ 1 ]); ctx.lineTo(this.x, this.y); ctx.strokeStyle = 'hsla(' + this.hue + ', 100%, ' + this.brightness + '%, ' + this.alpha + ')'; ctx.stroke();}// create particle group/explosionfunction createParticles(x, y) { // increase the particle count for a bigger explosion, beware of the canvas performance hit with the increased particles though var particleCount = 30; while (particleCount--) { particles.push(new Particle(x, y)); }}// main demo loopfunction loop() { // this function will run endlessly with requestAnimationFrame requestAnimFrame(loop); // increase the hue to get different colored fireworks over time hue += 0.5; // normally, clearRect() would be used to clear the canvas // we want to create a trailing effect though // setting the composite operation to destination-out will allow us to clear the canvas at a specific opacity, rather than wiping it entirely ctx.globalCompositeOperation = 'destination-out'; // decrease the alpha property to create more prominent trails ctx.fillStyle = 'rgba(0, 0, 0, 0.5)'; ctx.fillRect(0, 0, cw, ch); // change the composite operation back to our main mode // lighter creates bright highlight points as the fireworks and particles overlap each other ctx.globalCompositeOperation = 'lighter'; var text = "HAPPY NEW YEAR !"; ctx.font = "50px sans-serif"; var textData = ctx.measureText(text); ctx.fillStyle = "rgba(" + parseInt(random(0, 255)) + "," + parseInt(random(0, 255)) + "," + parseInt(random(0, 255)) + ",0.3)"; ctx.fillText(text, cw / 2 - textData.width / 2, ch / 2); // loop over each firework, draw it, update it var i = fireworks.length; while (i--) { fireworks[i].draw(); fireworks[i].update(i); } // loop over each particle, draw it, update it var i = particles.length; while (i--) { particles[i].draw(); particles[i].update(i); } // launch fireworks automatically to random coordinates, when the mouse isn't down if (timerTick >= timerTotal) { if (!mousedown) { // start the firework at the bottom middle of the screen, then set the random target coordinates, the random y coordinates will be set within the range of the top half of the screen for (var h = 0; h < 50; h++) { fireworks.push(new Firework(cw / 2, ch / 2, random(0, cw), random(0, ch))); } timerTick = 0; } } else { timerTick++; } // limit the rate at which fireworks get launched when mouse is down if (limiterTick >= limiterTotal) { if (mousedown) { // start the firework at the bottom middle of the screen, then set the current mouse coordinates as the target fireworks.push(new Firework(cw / 2, ch / 2, mx, my)); limiterTick = 0; } } else { limiterTick++; }}// mouse event bindings// update the mouse coordinates on mousemovecanvas.addEventListener('mousemove', function (e) { mx = e.pageX - canvas.offsetLeft; my = e.pageY - canvas.offsetTop;});// toggle mousedown state and prevent canvas from being selectedcanvas.addEventListener('mousedown', function (e) { e.preventDefault(); mousedown = true;});canvas.addEventListener('mouseup', function (e) { e.preventDefault(); mousedown = false;});// once the window loads, we are ready for some fireworks!window.onload = loop;实现二
html
<canvas></canvas><h2>201<span>8</span></h2>css
html,body { padding: 0px; margin: 0px; background: #222; font-family: 'Karla', sans-serif; color: #FFF; height: 100%; overflow: hidden;}h2 { z-index: 1000; position: fixed; top: 50%; left: 50%; transform: translateX(-50%) translateY(-100%); font-size: 58px; overflow: hidden;}span { position: relative; display: inline-block; animation: drop 0.75s ease 0s;}canvas { width: 100%; height: 100%;}@keyframes drop { 0% { transform: translateY(-100px); opacity: 0; } 90% { opacity: 1; transform: translateY(10px); } 100% { transform: translateY(0px); }}js
var ctx = document.querySelector('canvas').getContext('2d')ctx.canvas.width = window.innerWidthctx.canvas.height = window.innerHeightvar sparks = []var fireworks = []var i = 20;while (i--) { fireworks.push( new Firework(Math.random() * window.innerWidth, window.innerHeight * Math.random()) )}render()function render() { setTimeout(render, 1000 / 60) ctx.fillStyle = 'rgba(0, 0, 0, 0.1)'; ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height) for (var firework of fireworks) { if (firework.dead) continue firework.move() firework.draw() } for (var spark of sparks) { if (spark.dead) continue spark.move() spark.draw() } if (Math.random() < 0.05) { fireworks.push(new Firework()) }}function Spark(x, y, color) { this.x = x this.y = y this.dir = Math.random() * (Math.PI * 2) this.dead = false this.color = color this.speed = Math.random() * 3 + 3; this.walker = new Walker({ radius: 20, speed: 0.25 }) this.gravity = 0.25 this.dur = this.speed / 0.1 this.move = function () { this.dur-- if (this.dur < 0) this.dead = true if (this.speed < 0) return if (this.speed > 0) this.speed -= 0.1 var walk = this.walker.step() this.x += Math.cos(this.dir + walk) * this.speed this.y += Math.sin(this.dir + walk) * this.speed this.y += this.gravity this.gravity += 0.05 } this.draw = function () { drawCircle(this.x, this.y, 3, this.color) }}function Firework(x, y) { this.xmove = new Walker({ radius: 10, speed: 0.5 }) this.x = x || Math.random() * ctx.canvas.width this.y = y || ctx.canvas.height this.height = Math.random() * ctx.canvas.height / 2 this.dead = false this.color = randomColor() this.move = function () { this.x += this.xmove.step() if (this.y > this.height) this.y -= 1; else this.burst() } this.draw = function () { drawCircle(this.x, this.y, 1, this.color) } this.burst = function () { this.dead = true var i = 100; while (i--) sparks.push(new Spark(this.x, this.y, this.color)) }}function drawCircle(x, y, radius, color) { color = color || '#FFF' ctx.fillStyle = color ctx.fillRect(x - radius / 2, y - radius / 2, radius, radius)}function randomColor() { return ['#6ae5ab', '#88e3b2', '#36b89b', '#7bd7ec', '#66cbe1'][Math.floor(Math.random() * 5)];}function Walker(options) { this.step = function () { this.direction = Math.sign(this.target) * this.speed this.value += this.direction this.target ? this.target -= this.direction : (this.value) ? (this.wander) ? this.target = this.newTarget() : this.target = -this.value : this.target = this.newTarget() return this.direction } this.newTarget = function () { return Math.round(Math.random() * (this.radius * 2) - this.radius) } this.start = 0 this.value = 0 this.radius = options.radius this.target = this.newTarget() this.direction = Math.sign(this.target) this.wander = options.wander this.speed = options.speed || 1}实现三
html
<canvas id="cas" style="background-color:rgba(0,5,24,1)" width="1235" height="680">浏览器不支持canvas</canvas><div class="city"> <img src="city.png" alt=""></div><img src="moon.png" alt="" id="moon" style="visibility: hidden;"><div style="display:none"> <div class="shape">新年快乐</div> <div class="shape">阖家欢乐</div> <div class="shape">万事如意</div> <div class="shape">心想事成</div></div>css
body { margin: 0; padding: 0; overflow: hidden;}.city { width: 100%; position: fixed; bottom: 0px; z-index: 100;}.city img { width: 100%;}js
var canvas = document.getElementById("cas");var ocas = document.createElement("canvas");var octx = ocas.getContext("2d");var ctx = canvas.getContext("2d");ocas.width = canvas.width = window.innerWidth;ocas.height = canvas.height = window.innerHeight;var bigbooms = [];window.onload = function () { initAnimate()}function initAnimate() { drawBg(); lastTime = new Date(); animate();}var lastTime;function animate() { ctx.save(); ctx.fillStyle = "rgba(0,5,24,0.1)"; ctx.fillRect(0, 0, canvas.width, canvas.height); ctx.restore(); var newTime = new Date(); if (newTime - lastTime > 500 + (window.innerHeight - 767) / 2) { var random = Math.random() * 100 > 2 ? true : false; var x = getRandom(canvas.width / 5, canvas.width * 4 / 5); var y = getRandom(50, 200); if (random) { var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", { x: x, y: y }); bigbooms.push(bigboom) } else { var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", { x: canvas.width / 2, y: 200 }, document.querySelectorAll(".shape")[parseInt(getRandom(0, document.querySelectorAll( ".shape").length))]); bigbooms.push(bigboom) } lastTime = newTime; } stars.foreach(function () { this.paint(); }) drawMoon(); bigbooms.foreach(function (index) { var that = this; if (!this.dead) { this._move(); this._drawLight(); } else { this.booms.foreach(function (index) { if (!this.dead) { this.moveTo(index); } else if (index === that.booms.length - 1) { bigbooms[bigbooms.indexOf(that)] = null; } }) } }); raf(animate);}function drawMoon() { var moon = document.getElementById("moon"); var centerX = canvas.width - 200, centerY = 100, width = 80; if (moon.complete) { ctx.drawImage(moon, centerX, centerY, width, width) } else { moon.onload = function () { ctx.drawImage(moon, centerX, centerY, width, width) } } var index = 0; for (var i = 0; i < 10; i++) { ctx.save(); ctx.beginPath(); ctx.arc(centerX + width / 2, centerY + width / 2, width / 2 + index, 0, 2 * Math.PI); ctx.fillStyle = "rgba(240,219,120,0.005)"; index += 2; ctx.fill(); ctx.restore(); }}Array.prototype.foreach = function (callback) { for (var i = 0; i < this.length; i++) { if (this[i] !== null) callback.apply(this[i], [i]) }}var raf = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function (callback) { window.setTimeout(callback, 1000 / 60); };canvas.onclick = function () { var x = event.clientX; var y = event.clientY; var bigboom = new Boom(getRandom(canvas.width / 3, canvas.width * 2 / 3), 2, "#FFF", { x: x, y: y }); bigbooms.push(bigboom)}var Boom = function (x, r, c, boomArea, shape) { this.booms = []; this.x = x; this.y = (canvas.height + r); this.r = r; this.c = c; this.shape = shape || false; this.boomArea = boomArea; this.theta = 0; this.dead = false; this.ba = parseInt(getRandom(80, 200));}Boom.prototype = { _paint: function () { ctx.save(); ctx.beginPath(); ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI); ctx.fillStyle = this.c; ctx.fill(); ctx.restore(); }, _move: function () { var dx = this.boomArea.x - this.x, dy = this.boomArea.y - this.y; this.x = this.x + dx * 0.01; this.y = this.y + dy * 0.01; if (Math.abs(dx) <= this.ba && Math.abs(dy) <= this.ba) { if (this.shape) { this._shapBoom(); } else this._boom(); this.dead = true; } else { this._paint(); } }, _drawLight: function () { ctx.save(); ctx.fillStyle = "rgba(255,228,150,0.3)"; ctx.beginPath(); ctx.arc(this.x, this.y, this.r + 3 * Math.random() + 1, 0, 2 * Math.PI); ctx.fill(); ctx.restore(); }, _boom: function () { var fragNum = getRandom(30, 200); var style = getRandom(0, 10) >= 5 ? 1 : 2; var color; if (style === 1) { color = { a: parseInt(getRandom(128, 255)), b: parseInt(getRandom(128, 255)), c: parseInt(getRandom(128, 255)) } } var fanwei = parseInt(getRandom(300, 400)); for (var i = 0; i < fragNum; i++) { if (style === 2) { color = { a: parseInt(getRandom(128, 255)), b: parseInt(getRandom(128, 255)), c: parseInt(getRandom(128, 255)) } } var a = getRandom(-Math.PI, Math.PI); var x = getRandom(0, fanwei) * Math.cos(a) + this.x; var y = getRandom(0, fanwei) * Math.sin(a) + this.y; var radius = getRandom(0, 2) var frag = new Frag(this.x, this.y, radius, color, x, y); this.booms.push(frag); } }, _shapBoom: function () { var that = this; putValue(ocas, octx, this.shape, 5, function (dots) { var dx = canvas.width / 2 - that.x; var dy = canvas.height / 2 - that.y; for (var i = 0; i < dots.length; i++) { color = { a: dots[i].a, b: dots[i].b, c: dots[i].c } var x = dots[i].x; var y = dots[i].y; var radius = 1; var frag = new Frag(that.x, that.y, radius, color, x - dx, y - dy); that.booms.push(frag); } }) }}function putValue(canvas, context, ele, dr, callback) { context.clearRect(0, 0, canvas.width, canvas.height); var img = new Image(); if (ele.innerHTML.indexOf("img") >= 0) { img.src = ele.getElementsByTagName("img")[0].src; imgload(img, function () { context.drawImage(img, canvas.width / 2 - img.width / 2, canvas.height / 2 - img.width / 2); dots = getimgData(canvas, context, dr); callback(dots); }) } else { var text = ele.innerHTML; context.save(); var fontSize = 200; context.font = fontSize + "px 宋体 bold"; context.textAlign = "center"; context.textBaseline = "middle"; context.fillStyle = "rgba(" + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + "," + parseInt(getRandom(128, 255)) + " , 1)"; context.fillText(text, canvas.width / 2, canvas.height / 2); context.restore(); dots = getimgData(canvas, context, dr); callback(dots); }}function imgload(img, callback) { if (img.complete) { callback.call(img); } else { img.onload = function () { callback.call(this); } }}function getimgData(canvas, context, dr) { var imgData = context.getImageData(0, 0, canvas.width, canvas.height); context.clearRect(0, 0, canvas.width, canvas.height); var dots = []; for (var x = 0; x < imgData.width; x += dr) { for (var y = 0; y < imgData.height; y += dr) { var i = (y * imgData.width + x) * 4; if (imgData.data[i + 3] > 128) { var dot = { x: x, y: y, a: imgData.data[i], b: imgData.data[i + 1], c: imgData.data[i + 2] }; dots.push(dot); } } } return dots;}function getRandom(a, b) { return Math.random() * (b - a) + a;}var maxRadius = 1, stars = [];function drawBg() { for (var i = 0; i < 100; i++) { var r = Math.random() * maxRadius; var x = Math.random() * canvas.width; var y = Math.random() * 2 * canvas.height - canvas.height; var star = new Star(x, y, r); stars.push(star); star.paint() }}var Star = function (x, y, r) { this.x = x; this.y = y; this.r = r;}Star.prototype = { paint: function () { ctx.save(); ctx.beginPath(); ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI); ctx.fillStyle = "rgba(255,255,255," + this.r + ")"; ctx.fill(); ctx.restore(); }}var focallength = 250;var Frag = function (centerX, centerY, radius, color, tx, ty) { this.tx = tx; this.ty = ty; this.x = centerX; this.y = centerY; this.dead = false; this.centerX = centerX; this.centerY = centerY; this.radius = radius; this.color = color;}Frag.prototype = { paint: function () { ctx.save(); ctx.beginPath(); ctx.arc(this.x, this.y, this.radius, 0, 2 * Math.PI); ctx.fillStyle = "rgba(" + this.color.a + "," + this.color.b + "," + this.color.c + ",1)"; ctx.fill() ctx.restore(); }, moveTo: function (index) { this.ty = this.ty + 0.3; var dx = this.tx - this.x, dy = this.ty - this.y; this.x = Math.abs(dx) < 0.1 ? this.tx : (this.x + dx * 0.1); this.y = Math.abs(dy) < 0.1 ? this.ty : (this.y + dy * 0.1); if (dx === 0 && Math.abs(dy) <= 80) { this.dead = true; } this.paint(); }}以上是“怎么使用canvas实现烟花特效”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注编程网行业资讯频道！
