Comment créer un fond noir avec des feux d'artifice de débris d'effets spéciaux sur toile

Cette fois, je vais vous montrer comment réaliser des feux d'artifice en miettes avec un fond noir et des effets spéciaux à l'aide de toile. Quelles sont les précautions pour réaliser des feux d'artifice en miettes avec un fond noir et des effets spéciaux à l'aide de toile. est un cas pratique. Jetons un coup d'oeil.

<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: caché;
}.city { width: 100%; 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();
    }
}

Je crois que vous avez lu le cas dans cet article Vous maîtrisez la méthode. Pour des informations plus intéressantes, veuillez prêter attention aux autres articles connexes sur le site Web chinois de php !

Lecture recommandée :

Comment faire des feux d'artifice cyan avec fond noir sur toile

Comment faire du rouge avec fond noir en toile Feux d'artifice

Ce qui précède est le contenu détaillé de. pour plus d'informations, suivez d'autres articles connexes sur le site Web de PHP en chinois!