跳转至
Follow @Wcowin on
Bilibili and
Twitter

# 背景特效

Note

以下代码均在`docs/javascripts/extra.js`下复制粘贴

## 雪花❄️

      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    //雪花
    const fps = 30;
    const mspf = Math.floor(1000 / fps) ;

    let width = window.innerWidth || document.documentElement.clientWidth;
    let height = window.innerHeight || document.documentElement.clientHeight;
    let canvas;
    window.addEventListener('resize', () => {
      width = window.innerWidth || document.documentElement.clientWidth;
      height = window.innerHeight || document.documentElement.clientHeight;
      if (canvas) {
        canvas.width = width;
        canvas.height = height;
      }
    });

    let particles = [];
    let wind = [0, 0];
    let cursor = [0, 0];

    function velocity(r) {
      return 70 / r + 30;
    }

    function sine_component(h, a) {
      return [2 * Math.PI / h, Math.random() * a, Math.random() * 2 * Math.PI]; // [frequency, amplitude, phase]
    }

    function calc_sine(components, x) {
      let sum = 0;
      for (let i = 0; i < components.length; i++) {
        const [f, a, p] = components[i];
        sum += Math.sin(x * f + p) * a;
      }
      return sum;
    }

    function gen_particle() {
      let r = Math.random() * 4 + 1;
      return {
        radius: r,
        x: Math.random() * width,
        y: -r,
        opacity: Math.random(),
        sine_components: [sine_component(height, 3), sine_component(height / 2, 2), sine_component(height / 5, 1), sine_component(height / 10, 0.5)],
      };
    }

    function update_pos(dt) {
      const n = particles.length;
      for (let i = 0; i < n; i++) {
        const v = velocity(particles[i].radius);
        particles[i].x += calc_sine(particles[i].sine_components, particles[i].y) * v / 5 * dt;
        particles[i].y += v * dt;

        // const dist = Math.hypot(particles[i].x - cursor[0], particles[i].y - cursor[1]) + 1;
        // particles[i].x += wind[0] * dt / dist
        // particles[i].y += wind[1] * dt / dist;

        if (particles[i].y - particles[i].radius > height) {
          particles[i] = gen_particle();
        }
      }
    }

    let context_cache;
    function get_context() {
      if (context_cache)
        return context_cache;

      canvas = document.createElement('canvas');
      canvas.id = 'snow-canvas';
      canvas.width = width;
      canvas.height = height;
      canvas.style = 'position: fixed; top: 0; left: 0; overflow: hidden; pointer-events: none; z-index: 256;';
      if ((document.documentElement.dataset.darkreaderMode || "").startsWith('filter'))
        canvas.style.filter = 'invert(1)';
      document.body.appendChild(canvas);

      context_cache = canvas.getContext('2d');
      return context_cache;
    }

    function draw() {
      const ctx = get_context();

      ctx.clearRect(0, 0, width, height);

      const n = particles.length;
      for (let i = 0; i < n; i++) {
        const p = particles[i];
        ctx.fillStyle = `rgba(255, 255, 255, ${p.opacity})`;
        ctx.shadowColor = '#80EDF7';
        ctx.shadowBlur = 7;
        ctx.beginPath();
        ctx.arc(p.x, p.y, p.radius, 0, 2*Math.PI);
        ctx.fill();
      }
    }

    let focused = true;
    let disabled = false;
    let lastTime = performance.now();
    const requestFrame = () => setTimeout(loop, mspf);
    function loop() {
      const dt = (performance.now() - lastTime) / 1000;

      if (particles.length < 120 && Math.random() < 0.1) {
        particles.push(gen_particle());
      }

      update_pos(dt);
      draw();

      lastTime = performance.now();
      if (focused && !disabled)
        requestFrame();
    }

    window.addEventListener('focus', () => {
      console.log('snow start');
      focused = true;
      lastTime = performance.now();
      requestFrame();
    });

    window.addEventListener('blur', () => {
      console.log('snow stop');
      focused = false;
    });

    window.addEventListener('keydown', e => {
      if (e.ctrlKey && e.key == 's') {
        e.preventDefault();
        disabled = !disabled;
        if (disabled) {
          canvas.style.display = 'none';
        } else {
          canvas.style.display = 'block';
          lastTime = performance.now();
          requestFrame();
        }
      }
    });

    requestFrame();
    //雪花

## 樱花🌸

     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    //樱花
    Sakura.prototype.draw = function (cxt) {
        cxt.save(); var xc = 40 * this.s / 4; cxt.translate(this.x, this.y); cxt.rotate(this.r); cxt.drawImage(img, 0, 0, 40 * this.s, 40 * this.s)
        cxt.restore();
    }
    Sakura.prototype.update = function () { this.x = this.fn.x(this.x, this.y); this.y = this.fn.y(this.y, this.y); this.r = this.fn.r(this.r); if (this.x > window.innerWidth || this.x < 0 || this.y > window.innerHeight || this.y < 0) { this.r = getRandom('fnr'); if (Math.random() > 0.4) { this.x = getRandom('x'); this.y = 0; this.s = getRandom('s'); this.r = getRandom('r'); } else { this.x = window.innerWidth; this.y = getRandom('y'); this.s = getRandom('s'); this.r = getRandom('r'); } } }
    SakuraList = function () { this.list = []; }
    SakuraList.prototype.push = function (sakura) { this.list.push(sakura); }
    SakuraList.prototype.update = function () { for (var i = 0, len = this.list.length; i < len; i++) { this.list[i].update(); } }
    SakuraList.prototype.draw = function (cxt) { for (var i = 0, len = this.list.length; i < len; i++) { this.list[i].draw(cxt); } }
    SakuraList.prototype.get = function (i) { return this.list[i]; }
    SakuraList.prototype.size = function () { return this.list.length; }
    function getRandom(option) {
        var ret, random; switch (option) {
            case 'x': ret = Math.random() * window.innerWidth; break; case 'y': ret = Math.random() * window.innerHeight; break; case 's': ret = Math.random(); break; case 'r': ret = Math.random() * 6; break; case 'fnx': random = -0.5 + Math.random() * 1; ret = function (x, y) { return x + 0.5 * random - 1.7; }; break; case 'fny': random = 1.5 + Math.random() * 0.7
                ret = function (x, y) { return y + random; }; break; case 'fnr': random = Math.random() * 0.03; ret = function (r) { return r + random; }; break;
        }
        return ret;
    }
    function startSakura() {
        requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame || window.oRequestAnimationFrame; var canvas = document.createElement('canvas'), cxt; staticx = true; canvas.height = window.innerHeight; canvas.width = window.innerWidth; canvas.setAttribute('style', 'position: fixed;left: 0;top: 0;pointer-events: none;'); canvas.setAttribute('id', 'canvas_sakura'); document.getElementsByTagName('body')[0].appendChild(canvas); cxt = canvas.getContext('2d'); var sakuraList = new SakuraList(); for (var i = 0; i < 50; i++) { var sakura, randomX, randomY, randomS, randomR, randomFnx, randomFny; randomX = getRandom('x'); randomY = getRandom('y'); randomR = getRandom('r'); randomS = getRandom('s'); randomFnx = getRandom('fnx'); randomFny = getRandom('fny'); randomFnR = getRandom('fnr'); sakura = new Sakura(randomX, randomY, randomS, randomR, { x: randomFnx, y: randomFny, r: randomFnR }); sakura.draw(cxt); sakuraList.push(sakura); }
        stop = requestAnimationFrame(function () { cxt.clearRect(0, 0, canvas.width, canvas.height); sakuraList.update(); sakuraList.draw(cxt); stop = requestAnimationFrame(arguments.callee); })
    }
    window.onresize = function () { var canvasSnow = document.getElementById('canvas_snow'); }
    img.onload = function () { startSakura(); }
    //樱花

## 线条

     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    !function() {
        function o(w, v, i) {
            return w.getAttribute(v) || i
        }
        function j(i) {
            return document.getElementsByTagName(i)
        }
        function l() {
            var i = j("script"),
            w = i.length,
            v = i[w - 1];
            return {
                l: w,
                z: o(v, "zIndex", -1),
                o: o(v, "opacity", 0.5),
                c: o(v, "color", "0,0,0"),
                n: o(v, "count", 99)
            }
        }
        function k() {
            r = u.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth,
            n = u.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight
        }
        function b() {
            e.clearRect(0, 0, r, n);
            var w = [f].concat(t);
            var x, v, A, B, z, y;
            t.forEach(function(i) {
                i.x += i.xa,
                i.y += i.ya,
                i.xa *= i.x > r || i.x < 0 ? -1 : 1,
                i.ya *= i.y > n || i.y < 0 ? -1 : 1,
                e.fillRect(i.x - 0.5, i.y - 0.5, 1, 1);
                for (v = 0; v < w.length; v++) {
                    x = w[v];
                    if (i !== x && null !== x.x && null !== x.y) {
                        B = i.x - x.x,
                        z = i.y - x.y,
                        y = B * B + z * z;
                        y < x.max && (x === f && y >= x.max / 2 && (i.x -= 0.03 * B, i.y -= 0.03 * z), A = (x.max - y) / x.max, e.beginPath(), e.lineWidth = A / 2, e.strokeStyle = "rgba(" + s.c + "," + (A + 0.2) + ")", e.moveTo(i.x, i.y), e.lineTo(x.x, x.y), e.stroke())
                    }
                }
                w.splice(w.indexOf(i), 1)
            }),
            m(b)
        }
        var u = document.createElement("canvas"),
        s = l(),
        c = "c_n" + s.l,
        e = u.getContext("2d"),
        r,
        n,
        m = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
        function(i) {
            window.setTimeout(i, 1000 / 45)
        },
        a = Math.random,
        f = {
            x: null,
            y: null,
            max: 20000
        };
        u.id = c;
        u.style.cssText = "position:fixed;top:0;left:0;z-index:" + s.z + ";opacity:" + s.o;
        j("body")[0].appendChild(u);
        k(),
        window.onresize = k;
        window.onmousemove = function(i) {
            i = i || window.event,
            f.x = i.clientX,
            f.y = i.clientY
        },
        window.onmouseout = function() {
            f.x = null,
            f.y = null
        };
        for (var t = [], p = 0; s.n > p; p++) {
            var h = a() * r,
            g = a() * n,
            q = 2 * a() - 1,
            d = 2 * a() - 1;
            t.push({
                x: h,
                y: g,
                xa: q,
                ya: d,
                max: 6000
            })
        }
        setTimeout(function() {
            b()
        },
        100)
    } ();

## 粒子

      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    /*背景*/
    window.onload = function () {
        //定义body的margin由默认值8px->0px
        document.body.style.margin = "0";
        document.body.style.background = "255,255,255";
        //创建canvas画布
        document.body.appendChild(document.createElement('canvas'));
        var canvas = document.querySelector('canvas'),
            ctx = canvas.getContext('2d') //ctx返回一个在canvas上画图的api/dom
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;
        canvas.style.position = 'fixed';
        ctx.lineWidth = .3;
        ctx.strokeStyle = (new Color(150)).style;
        //定义鼠标覆盖范围
        var mousePosition = {
            x: 30 * canvas.width / 100,
            y: 30 * canvas.height / 100
        };
        var dots = {
            nb: 1000,//Dot的总数
            distance: 50,
            d_radius: 100,
            array: []
        };
        //创建颜色类，Color类返回字符串型rgba（*,*,*,.8）
        function mixComponents(comp1, weight1, comp2, weight2) {
            return (comp1 * weight1 + comp2 * weight2) / (weight1 + weight2);
        }
        function averageColorStyles(dot1, dot2) {
            var color1 = dot1.color,
                color2 = dot2.color;

            var r = mixComponents(color1.r, dot1.radius, color2.r, dot2.radius),
                g = mixComponents(color1.g, dot1.radius, color2.g, dot2.radius),
                b = mixComponents(color1.b, dot1.radius, color2.b, dot2.radius);
            return createColorStyle(Math.floor(r), Math.floor(g), Math.floor(b));
        }
        function colorValue(min) {
            return Math.floor(Math.random() * 255 + min);
        }
        function createColorStyle(r, g, b) {
            return 'rgba(' + r + ',' + g + ',' + b + ', 0.8)';
        }
        function Color(min) {
            min = min || 0;
            this.r = colorValue(min);
            this.g = colorValue(min);
            this.b = colorValue(min);
            this.style = createColorStyle(this.r, this.g, this.b);
        }
        //创建Dot类以及一系列方法
        function Dot() {
            this.x = Math.random() * canvas.width;
            this.y = Math.random() * canvas.height;

            this.vx = -.5 + Math.random();
            this.vy = -.5 + Math.random();

            this.radius = Math.random() * 2;

            this.color = new Color();
        }

        Dot.prototype = {
            draw: function () {
                ctx.beginPath();
                ctx.fillStyle = this.color.style;
                ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
                ctx.fill();
            }
        };
        function moveDots() {//Dot对象的移动
            for (i = 0; i < dots.nb; i++) {

                var dot = dots.array[i];

                if (dot.y < 0 || dot.y > canvas.height) {
                    dot.vx = dot.vx;
                    dot.vy = - dot.vy;
                }
                else if (dot.x < 0 || dot.x > canvas.width) {
                    dot.vx = - dot.vx;
                    dot.vy = dot.vy;
                }
                dot.x += dot.vx;
                dot.y += dot.vy;
            }
        }
        function connectDots() {//DOt对象的连接
            for (i = 0; i < dots.nb; i++) {
                for (j = i; j < dots.nb; j++) {
                    i_dot = dots.array[i];
                    j_dot = dots.array[j];

                    if ((i_dot.x - j_dot.x) < dots.distance && (i_dot.y - j_dot.y) < dots.distance && (i_dot.x - j_dot.x) > - dots.distance && (i_dot.y - j_dot.y) > - dots.distance) {
                        if ((i_dot.x - mousePosition.x) < dots.d_radius && (i_dot.y - mousePosition.y) < dots.d_radius && (i_dot.x - mousePosition.x) > - dots.d_radius && (i_dot.y - mousePosition.y) > - dots.d_radius) {
                            ctx.beginPath();
                            ctx.strokeStyle = averageColorStyles(i_dot, j_dot);
                            ctx.moveTo(i_dot.x, i_dot.y);
                            ctx.lineTo(j_dot.x, j_dot.y);
                            ctx.stroke();//绘制定义的路线
                            ctx.closePath();//创建从当前点回到起始点的路径
                        }
                    }
                }
            }
        }
        function createDots() {//创建nb个Dot对象
            for (i = 0; i < dots.nb; i++) {
                dots.array.push(new Dot());
            }
        }
        function drawDots() {//引用Dot原型链，使用draw方法，在canvas上画出Dot对象
            for (i = 0; i < dots.nb; i++) {
                var dot = dots.array[i];
                dot.draw();
            }
        }
        function animateDots() {
            ctx.clearRect(0, 0, canvas.width, canvas.height);//清除画布，否则线条会连在一起
            moveDots();
            connectDots();
            drawDots();
            requestAnimationFrame(animateDots);
        }
        createDots();//使用创建Dot类函数
        requestAnimationFrame(animateDots);//使用canvas独有的60Hz刷新屏幕画布的方法

        document.querySelector('canvas').addEventListener('mousemove', function (e) {
            mousePosition.x = e.pageX;
            mousePosition.y = e.pageY;
        })

        document.querySelector('canvas').addEventListener('mouseleave', function (e) {//鼠标离开时，连接自动返回到画布中心
            mousePosition.x = canvas.width / 2;
            mousePosition.y = canvas.height / 2;
        })

    }

    /*背景end*/

此页面有帮助吗？
谢谢你的反馈！
Thanks for your feedback! Help us improve this page by using our feedback form.