キャンバスに黒い背景を持つシアンの花火を作る方法

今回はキャンバスを使って黒背景のシアンの花火を作る方法を紹介します。 キャンバスを使って黒背景のシアンの花火を作るときの注意点は何ですか。実際の事例を見てみましょう。

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(&#39;canvas&#39;).getContext(&#39;2d&#39;)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 = &#39;rgba(0, 0, 0, 0.1)&#39;;    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 || &#39;#FFF&#39;    ctx.fillStyle = color    ctx.fillRect(x - radius / 2, y - radius / 2, radius, radius)}function randomColor() {    return [&#39;#6ae5ab&#39;, &#39;#88e3b2&#39;, &#39;#36b89b&#39;, &#39;#7bd7ec&#39;, &#39;#66cbe1&#39;][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}

この記事の事例を読んだ後は、この方法を習得したと思います。さらに興味深い内容については、PHP 中国語 Web サイトの他の関連記事に注目してください。

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以上がキャンバスに黒い背景を持つシアンの花火を作る方法の詳細内容です。詳細については、PHP 中国語 Web サイトの他の関連記事を参照してください。