https://cikian.github.io/libs/background/canvas-nest.js

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