canvas烟花绽放美丽动画效果代码

canvas烟花绽放美丽动画效果代码
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">

    <style>
        * {
            margin: 0;
            padding: 0;
            font-family: "微软雅黑";
        }
        .box {
            width: 80vw;
            margin: 0 auto;
            background: #EFEFEF;
            position: absolute;
            /*left: 0;*/
            left: calc(50% - 40vw);
            /*水平居中*/
            top: 0;
        }
        #name {
            padding: 60px;
            font-size: 40px;
            font-weight: 900;
            text-align: center;
            background: url(images/6.jpg) no-repeat center;
            /*以盒子内的文字作为裁剪区域向外裁剪,文字之外的区域都将被裁剪掉*/
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            /*文字颜色填充*/
        }
        h1 {
            letter-spacing: 3px;
            height: 70px;
            line-height: 70px;
            background: #ccc;
            text-align: center;
            -webkit-text-stroke: 1px #000;
            /*字体描边*/
            -webkit-text-fill-color: transparent;
            /*谷歌内核特有的属性*/
        }
        #bt {
            height: 50px;
            line-height: 50px;
            background: deepskyblue;
            text-align: center;
            color: #fff;
            cursor: pointer;
        }
  
    </style>
</head>
<body id="bodyid">
    <canvas id="canvas"></canvas>

    <script type="text/javascript" src="//repo.bfw.wiki/bfwrepo/js/jquery-3.2.1.min.js"></script>

    <script>
        $(function() {
            var canvas = $('#canvas')[0];
            canvas.width = $(window).width();
            canvas.height = $(window).height();
            var ctx = canvas.getContext('2d');

            // resize
            $(window).on('resize', function() {
                canvas.width = $(window).width();
                canvas.height = $(window).height();
                ctx.fillStyle = '#000';
                ctx.fillRect(0, 0, canvas.width, canvas.height);
            });

            // init
            ctx.fillStyle = '#000';
            ctx.fillRect(0, 0, canvas.width, canvas.height);
            // objects
            var listFire = [];
            var listFirework = [];
            var fireNumber = 10;
            var center = {
                x: canvas.width / 2, y: canvas.height / 1.5
            };
            var range = 100;
            for (var i = 0; i < fireNumber; i++) {
                var fire = {
                    x: Math.random() * range / 2 - range / 4 + center.x,
                    y: Math.random() * range * 2 + canvas.height,
                    size: Math.random() + 0.5,
                    fill: '#fd1',
                    vx: Math.random() - 0.5,
                    vy: -(Math.random() + 4),
                    ax: Math.random() * 0.02 - 0.01,
                    far: Math.random() * range + (center.y - range)
                };
                fire.base = {
                    x: fire.x,
                    y: fire.y,
                    vx: fire.vx
                };
                //
                listFire.push(fire);
            }

            function randColor() {
                var r = Math.floor(Math.random() * 256);
                var g = Math.floor(Math.random() * 256);
                var b = Math.floor(Math.random() * 256);
                var color = 'rgb($r, $g, $b)';
                color = color.replace('$r', r);
                color = color.replace('$g', g);
                color = color.replace('$b', b);
                return color;
            }

            (function loop() {
                requestAnimationFrame(loop);
                update();
                draw();
            })();


            function update() {
                for (var i = 0; i < listFire.length; i++) {
                    var fire = listFire[i];
                    //
                    if (fire.y <= fire.far) {
                        // case add firework
                        var color = randColor();
                        for (var i = 0; i < fireNumber * 5; i++) {
                            var firework = {
                                x: fire.x,
                                y: fire.y,
                                size: Math.random() + 1.5,
                                fill: color,
                                vx: Math.random() * 5 - 2.5,
                                vy: Math.random() * -5 + 1.5,
                                ay: 0.05,
                                alpha: 1,
                                life: Math.round(Math.random() * range / 2) + range / 2
                            };
                            firework.base = {
                                life: firework.life,
                                size: firework.size
                            };
                            listFirework.push(firework);
                        }
                        // reset
                        fire.y = fire.base.y;
                        fire.x = fire.base.x;
                        fire.vx = fire.base.vx;
                        fire.ax = Math.random() * 0.02 - 0.01;
                    }
                    //
                    fire.x += fire.vx;
                    fire.y += fire.vy;
                    fire.vx += fire.ax;
                }

                for (var i = listFirework.length - 1; i >= 0; i--) {
                    var firework = listFirework[i];
                    if (firework) {
                        firework.x += firework.vx;
                        firework.y += firework.vy;
                        firework.vy += firework.ay;
                        firework.alpha = firework.life / firework.base.life;
                        firework.size = firework.alpha * firework.base.size;
                        firework.alpha = firework.alpha > 0.6 ? 1: firework.alpha;
                        //
                        firework.life--;
                        if (firework.life <= 0) {
                            listFirework.splice(i, 1);
                        }
                    }
                }
            }

            function draw() {
                // clear
                ctx.globalCompositeOperation = 'source-over';
                ctx.globalAlpha = 0.18;
                ctx.fillStyle = '#000';
                ctx.fillRect(0, 0, canvas.width, canvas.height);

                // re-draw
                ctx.globalCompositeOperation = 'screen';
                ctx.globalAlpha = 1;
                for (var i = 0; i < listFire.length; i++) {
                    var fire = listFire[i];
                    ctx.beginPath();
                    ctx.arc(fire.x, fire.y, fire.size, 0, Math.PI * 2);
                    ctx.closePath();
                    ctx.fillStyle = fire.fill;
                    ctx.fill();
                }

                for (var i = 0; i < listFirework.length; i++) {
                    var firework = listFirework[i];
                    ctx.globalAlpha = firework.alpha;
                    ctx.beginPath();
                    ctx.arc(firework.x, firework.y, firework.size, 0, Math.PI * 2);
                    ctx.closePath();
                    ctx.fillStyle = firework.fill;
                    ctx.fill();
                }
            }
        });
        //点名事件
        
    </script>
</body>
</html>

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