添加 Cherry 樱花雨背景特效

樱花雨 Cherry 背景特效

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

.cherry-container {
  position: fixed;
  width: 100%;
  height: 100vh;
  margin: 0;
  padding: 0;
  left: 0;
  top: 0;
  z-index: -1;
}

修改 [Blogroot]\themes\butterfly\layout\includes\layout.pug,在第 19 行左右添加元素 id 绑定

    if page.type !== '404'
+      #jsi-cherry-container(class='cherry-container')
      #body-wrap(class=pageType)
        include ./header/index.pug

新建 [Blogroot]\themes\butterfly\source\js\cherry.js

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();
});

引入对应的资源,修改 _config.butterfly.yml,在 inject 配置项添加 cherry.js

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>