樱花雨 Cherry 背景特效

  1. 新建 [Blogroot]\themes\butterfly\source\css\custom\index.css, 添加 Canvas 默认样式。

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    .cherry-container {
    position: fixed;
    width: 100%;
    height: 100vh;
    margin: 0;
    padding: 0;
    left: 0;
    top: 0;
    z-index: -1;
    }
  2. 修改 [Blogroot]\themes\butterfly\layout\includes\layout.pug,在第 19 行左右添加元素 id 绑定

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        if page.type !== '404'
    + #jsi-cherry-container(class='cherry-container')
    #body-wrap(class=pageType)
    include ./header/index.pug
  3. 新建 [Blogroot]\themes\butterfly\source\js\cherry.js

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    var RENDERER = {
    INIT_CHERRY_BLOSSOM_COUNT: 30,
    MAX_ADDING_INTERVAL: 10,

    init: function () {
    this.setParameters();
    this.reconstructMethods();
    this.createCherries();
    this.render();
    },
    setParameters: function () {
    this.$container = $('#jsi-cherry-container');
    this.width = this.$container.width();
    this.height = this.$container.height();
    this.context = $('<canvas />').attr({ width: this.width, height: this.height }).appendTo(this.$container).get(0).getContext('2d');
    this.cherries = [];
    this.maxAddingInterval = Math.round(this.MAX_ADDING_INTERVAL * 1000 / this.width);
    this.addingInterval = this.maxAddingInterval;
    },
    reconstructMethods: function () {
    this.render = this.render.bind(this);
    },
    createCherries: function () {
    for (var i = 0, length = Math.round(this.INIT_CHERRY_BLOSSOM_COUNT * this.width / 1000); i < length; i++) {
    this.cherries.push(new CHERRY_BLOSSOM(this, true));
    }
    },
    render: function () {
    requestAnimationFrame(this.render);
    this.context.clearRect(0, 0, this.width, this.height);

    this.cherries.sort(function (cherry1, cherry2) {
    return cherry1.z - cherry2.z;
    });
    for (var i = this.cherries.length - 1; i >= 0; i--) {
    if (!this.cherries[i].render(this.context)) {
    this.cherries.splice(i, 1);
    }
    }
    if (--this.addingInterval == 0) {
    this.addingInterval = this.maxAddingInterval;
    this.cherries.push(new CHERRY_BLOSSOM(this, false));
    }
    }
    };
    var CHERRY_BLOSSOM = function (renderer, isRandom) {
    this.renderer = renderer;
    this.init(isRandom);
    };
    CHERRY_BLOSSOM.prototype = {
    FOCUS_POSITION: 300,
    FAR_LIMIT: 600,
    MAX_RIPPLE_COUNT: 100,
    RIPPLE_RADIUS: 100,
    SURFACE_RATE: 0.5,
    SINK_OFFSET: 20,

    init: function (isRandom) {
    this.x = this.getRandomValue(-this.renderer.width, this.renderer.width);
    this.y = isRandom ? this.getRandomValue(0, this.renderer.height) : this.renderer.height * 1.5;
    this.z = this.getRandomValue(0, this.FAR_LIMIT);
    this.vx = this.getRandomValue(-2, 2);
    this.vy = -2;
    this.theta = this.getRandomValue(0, Math.PI * 2);
    this.phi = this.getRandomValue(0, Math.PI * 2);
    this.psi = 0;
    this.dpsi = this.getRandomValue(Math.PI / 600, Math.PI / 300);
    this.opacity = 0;
    this.endTheta = false;
    this.endPhi = false;
    this.rippleCount = 0;

    var axis = this.getAxis(),
    theta = this.theta + Math.ceil(-(this.y + this.renderer.height * this.SURFACE_RATE) / this.vy) * Math.PI / 500;
    theta %= Math.PI * 2;

    this.offsetY = 40 * ((theta <= Math.PI / 2 || theta >= Math.PI * 3 / 2) ? -1 : 1);
    this.thresholdY = this.renderer.height / 2 + this.renderer.height * this.SURFACE_RATE * axis.rate;
    this.entityColor = this.renderer.context.createRadialGradient(0, 40, 0, 0, 40, 80);
    this.entityColor.addColorStop(0, 'hsl(330, 70%, ' + 50 * (0.3 + axis.rate) + '%)');
    this.entityColor.addColorStop(0.05, 'hsl(330, 40%,' + 55 * (0.3 + axis.rate) + '%)');
    this.entityColor.addColorStop(1, 'hsl(330, 20%, ' + 70 * (0.3 + axis.rate) + '%)');
    this.shadowColor = this.renderer.context.createRadialGradient(0, 40, 0, 0, 40, 80);
    this.shadowColor.addColorStop(0, 'hsl(330, 40%, ' + 30 * (0.3 + axis.rate) + '%)');
    this.shadowColor.addColorStop(0.05, 'hsl(330, 40%,' + 30 * (0.3 + axis.rate) + '%)');
    this.shadowColor.addColorStop(1, 'hsl(330, 20%, ' + 40 * (0.3 + axis.rate) + '%)');
    },
    getRandomValue: function (min, max) {
    return min + (max - min) * Math.random();
    },
    getAxis: function () {
    var rate = this.FOCUS_POSITION / (this.z + this.FOCUS_POSITION),
    x = this.renderer.width / 2 + this.x * rate,
    y = this.renderer.height / 2 - this.y * rate;
    return { rate: rate, x: x, y: y };
    },
    renderCherry: function (context, axis) {
    context.beginPath();
    context.moveTo(0, 40);
    context.bezierCurveTo(-60, 20, -10, -60, 0, -20);
    context.bezierCurveTo(10, -60, 60, 20, 0, 40);
    context.fill();

    for (var i = -4; i < 4; i++) {
    context.beginPath();
    context.moveTo(0, 40);
    context.quadraticCurveTo(i * 12, 10, i * 4, -24 + Math.abs(i) * 2);
    context.stroke();
    }
    },
    render: function (context) {
    var axis = this.getAxis();

    if (axis.y == this.thresholdY && this.rippleCount < this.MAX_RIPPLE_COUNT) {
    context.save();
    context.lineWidth = 2;
    context.strokeStyle = 'hsla(0, 0%, 100%, ' + (this.MAX_RIPPLE_COUNT - this.rippleCount) / this.MAX_RIPPLE_COUNT + ')';
    context.translate(axis.x + this.offsetY * axis.rate * (this.theta <= Math.PI ? -1 : 1), axis.y);
    context.scale(1, 0.3);
    context.beginPath();
    context.arc(0, 0, this.rippleCount / this.MAX_RIPPLE_COUNT * this.RIPPLE_RADIUS * axis.rate, 0, Math.PI * 2, false);
    context.stroke();
    context.restore();
    this.rippleCount++;
    }
    if (axis.y < this.thresholdY || (!this.endTheta || !this.endPhi)) {
    if (this.y <= 0) {
    this.opacity = Math.min(this.opacity + 0.01, 1);
    }
    context.save();
    context.globalAlpha = this.opacity;
    context.fillStyle = this.shadowColor;
    context.strokeStyle = 'hsl(330, 30%,' + 40 * (0.3 + axis.rate) + '%)';
    context.translate(axis.x, Math.max(axis.y, this.thresholdY + this.thresholdY - axis.y));
    context.rotate(Math.PI - this.theta);
    context.scale(axis.rate * -Math.sin(this.phi), axis.rate);
    context.translate(0, this.offsetY);
    this.renderCherry(context, axis);
    context.restore();
    }
    context.save();
    context.fillStyle = this.entityColor;
    context.strokeStyle = 'hsl(330, 40%,' + 70 * (0.3 + axis.rate) + '%)';
    context.translate(axis.x, axis.y + Math.abs(this.SINK_OFFSET * Math.sin(this.psi) * axis.rate));
    context.rotate(this.theta);
    context.scale(axis.rate * Math.sin(this.phi), axis.rate);
    context.translate(0, this.offsetY);
    this.renderCherry(context, axis);
    context.restore();

    if (this.y <= -this.renderer.height / 4) {
    if (!this.endTheta) {
    for (var theta = Math.PI / 2, end = Math.PI * 3 / 2; theta <= end; theta += Math.PI) {
    if (this.theta < theta && this.theta + Math.PI / 200 > theta) {
    this.theta = theta;
    this.endTheta = true;
    break;
    }
    }
    }
    if (!this.endPhi) {
    for (var phi = Math.PI / 8, end = Math.PI * 7 / 8; phi <= end; phi += Math.PI * 3 / 4) {
    if (this.phi < phi && this.phi + Math.PI / 200 > phi) {
    this.phi = Math.PI / 8;
    this.endPhi = true;
    break;
    }
    }
    }
    }
    if (!this.endTheta) {
    if (axis.y == this.thresholdY) {
    this.theta += Math.PI / 200 * ((this.theta < Math.PI / 2 || (this.theta >= Math.PI && this.theta < Math.PI * 3 / 2)) ? 1 : -1);
    } else {
    this.theta += Math.PI / 500;
    }
    this.theta %= Math.PI * 2;
    }
    if (this.endPhi) {
    if (this.rippleCount == this.MAX_RIPPLE_COUNT) {
    this.psi += this.dpsi;
    this.psi %= Math.PI * 2;
    }
    } else {
    this.phi += Math.PI / ((axis.y == this.thresholdY) ? 200 : 500);
    this.phi %= Math.PI;
    }
    if (this.y <= -this.renderer.height * this.SURFACE_RATE) {
    this.x += 2;
    this.y = -this.renderer.height * this.SURFACE_RATE;
    } else {
    this.x += this.vx;
    this.y += this.vy;
    }
    return this.z > -this.FOCUS_POSITION && this.z < this.FAR_LIMIT && this.x < this.renderer.width * 1.5;
    }
    };
    $(function () {
    RENDERER.init();
    });
  4. 引入对应的资源,修改 _config.butterfly.yml,在 inject 配置项添加 cherry.js

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    inject:
    head:
    - <link rel="stylesheet" href="/css/custom/index.css" media="defer" onload="this.media='all'">
    - <script src="https://www.jq22.com/jquery/jquery-3.3.1.js"></script>
    bottom:
    - <script src="/js/cherry.js" async></script>

需要 jQuery 支持,引入静态资源,不然会报 $ is not defined

  1. 执行 hexo c,hexo g,hexo s,大功告成,不出意外的话,就能正常显示了