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。

firework

原文链接

实现一

firework

效果地址

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 shim
window.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 demo
var 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 dimensions
canvas.width = cw;
canvas.height = ch;

// now we are going to setup our function placeholders for the entire demo

// get a random number within a range
function random(min, max) {
    return Math.random() * (max - min) + min;
}

// calculate the distance between two points
function calculateDistance(p1x, p1y, p2x, p2y) {
    var xDistance = p1x - p2x,
        yDistance = p1y - p2y;
    return Math.sqrt(Math.pow(xDistance, 2) + Math.pow(yDistance, 2));
}

// create firework
function 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 firework
Firework.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 firework
Firework.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 particle
function 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 particle
Particle.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 particle
Particle.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/explosion
function 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 loop
function 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 mousemove
canvas.addEventListener('mousemove', function (e) {
    mx = e.pageX - canvas.offsetLeft;
    my = e.pageY - canvas.offsetTop;
});

// toggle mousedown state and prevent canvas from being selected
canvas.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

firework
效果地址

html

<canvas></canvas>
<h1>201<span>8</span></h1>

css

html,
body {
    padding: 0px;
    margin: 0px;
    background: #222;
    font-family: 'Karla', sans-serif;
    color: #FFF;
    height: 100%;
    overflow: hidden;
}

h1 {
    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.innerWidth
ctx.canvas.height = window.innerHeight

var 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

firework
效果地址

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();
    }
}

总结

几种不同canvas实现烟花动画，基本分为烟火类和碎屑类展现烟花的不同状态。
同时，祝大家新年快乐！