SVG 随机噪音对象生成图

Source: http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf

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JavaScript

/**
 * You can pass in a random number generator object if you like.
 * It is assumed to have a random() method.
 */
var SimplexNoise = function(r) {
    if (r == undefined) r = Math;
    this.grad3 = [
        [1, 1, 0],
        [-1, 1, 0],
        [1, -1, 0],
        [-1, -1, 0],
        [1, 0, 1],
        [-1, 0, 1],
        [1, 0, -1],
        [-1, 0, -1],
        [0, 1, 1],
        [0, -1, 1],
        [0, 1, -1],
        [0, -1, -1]
    ];
    this.p = [];
    for (var i = 0; i < 256; i++) {
        this.p[i] = Math.floor(r.random() * 256);
    }
    // To remove the need for index wrapping, double the permutation table length 
    this.perm = [];
    for (var i = 0; i < 512; i++) {
        this.perm[i] = this.p[i & 255];
    }

// A lookup table to traverse the simplex around a given point in 4D. 
    // Details can be found where this table is used, in the 4D noise method. 
    this.simplex = [
        [0, 1, 2, 3],
        [0, 1, 3, 2],
        [0, 0, 0, 0],
        [0, 2, 3, 1],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [1, 2, 3, 0],
        [0, 2, 1, 3],
        [0, 0, 0, 0],
        [0, 3, 1, 2],
        [0, 3, 2, 1],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [1, 3, 2, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [1, 2, 0, 3],
        [0, 0, 0, 0],
        [1, 3, 0, 2],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [2, 3, 0, 1],
        [2, 3, 1, 0],
        [1, 0, 2, 3],
        [1, 0, 3, 2],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [2, 0, 3, 1],
        [0, 0, 0, 0],
        [2, 1, 3, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [2, 0, 1, 3],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [3, 0, 1, 2],
        [3, 0, 2, 1],
        [0, 0, 0, 0],
        [3, 1, 2, 0],
        [2, 1, 0, 3],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0],
        [3, 1, 0, 2],
        [0, 0, 0, 0],
        [3, 2, 0, 1],
        [3, 2, 1, 0]
    ];
};

SimplexNoise.prototype.dot = function(g, x, y) {
    return g[0] * x + g[1] * y;
};

SimplexNoise.prototype.noise = function(xin, yin) {
    var n0, n1, n2; // Noise contributions from the three corners 
    // Skew the input space to determine which simplex cell we're in 
    var F2 = 0.5 * (Math.sqrt(3.0) - 1.0);
    var s = (xin + yin) * F2; // Hairy factor for 2D 
    var i = Math.floor(xin + s);
    var j = Math.floor(yin + s);
    var G2 = (3.0 - Math.sqrt(3.0)) / 6.0;
    var t = (i + j) * G2;
    var X0 = i - t; // Unskew the cell origin back to (x,y) space 
    var Y0 = j - t;
    var x0 = xin - X0; // The x,y distances from the cell origin 
    var y0 = yin - Y0;
    // For the 2D case, the simplex shape is an equilateral triangle. 
    // Determine which simplex we are in. 
    var i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords 
    if (x0 > y0) {
        i1 = 1;
        j1 = 0;
    } // lower triangle, XY order: (0,0)->(1,0)->(1,1) 
    else {
        i1 = 0;
        j1 = 1;
    } // upper triangle, YX order: (0,0)->(0,1)->(1,1) 
    // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and 
    // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where 
    // c = (3-sqrt(3))/6 
    var x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords 
    var y1 = y0 - j1 + G2;
    var x2 = x0 - 1.0 + 2.0 * G2; // Offsets for last corner in (x,y) unskewed coords 
    var y2 = y0 - 1.0 + 2.0 * G2;
    // Work out the hashed gradient indices of the three simplex corners 
    var ii = i & 255;
    var jj = j & 255;
    var gi0 = this.perm[ii + this.perm[jj]] % 12;
    var gi1 = this.perm[ii + i1 + this.perm[jj + j1]] % 12;
    var gi2 = this.perm[ii + 1 + this.perm[jj + 1]] % 12;
    // Calculate the contribution from the three corners 
    var t0 = 0.5 - x0 * x0 - y0 * y0;
    if (t0 < 0) n0 = 0.0;
    else {
        t0 *= t0;
        n0 = t0 * t0 * this.dot(this.grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient 
    }
    var t1 = 0.5 - x1 * x1 - y1 * y1;
    if (t1 < 0) n1 = 0.0;
    else {
        t1 *= t1;
        n1 = t1 * t1 * this.dot(this.grad3[gi1], x1, y1);
    }
    var t2 = 0.5 - x2 * x2 - y2 * y2;
    if (t2 < 0) n2 = 0.0;
    else {
        t2 *= t2;
        n2 = t2 * t2 * this.dot(this.grad3[gi2], x2, y2);
    }
    // Add contributions from each corner to get the final noise value. 
    // The result is scaled to return values in the interval [-1,1]. 
    return 70.0 * (n0 + n1 + n2);
};

// 3D simplex noise 
SimplexNoise.prototype.noise3d = function(xin, yin, zin) {
    var n0, n1, n2, n3; // Noise contributions from the four corners 
    // Skew the input space to determine which simplex cell we're in 
    var F3 = 1.0 / 3.0;
    var s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D 
    var i = Math.floor(xin + s);
    var j = Math.floor(yin + s);
    var k = Math.floor(zin + s);
    var G3 = 1.0 / 6.0; // Very nice and simple unskew factor, too 
    var t = (i + j + k) * G3;
    var X0 = i - t; // Unskew the cell origin back to (x,y,z) space 
    var Y0 = j - t;
    var Z0 = k - t;
    var x0 = xin - X0; // The x,y,z distances from the cell origin 
    var y0 = yin - Y0;
    var z0 = zin - Z0;
    // For the 3D case, the simplex shape is a slightly irregular tetrahedron. 
    // Determine which simplex we are in. 
    var i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords 
    var i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords 
    if (x0 >= y0) {
        if (y0 >= z0) {
            i1 = 1;
            j1 = 0;
            k1 = 0;
            i2 = 1;
            j2 = 1;
            k2 = 0;
        } // X Y Z order 
        else if (x0 >= z0) {
            i1 = 1;
            j1 = 0;
            k1 = 0;
            i2 = 1;
            j2 = 0;
            k2 = 1;
        } // X Z Y order 
        else {
            i1 = 0;
            j1 = 0;
            k1 = 1;
            i2 = 1;
            j2 = 0;
            k2 = 1;
        } // Z X Y order 
    } else { // x0<y0 
        if (y0 < z0) {
            i1 = 0;
            j1 = 0;
            k1 = 1;
            i2 = 0;
            j2 = 1;
            k2 = 1;
        } // Z Y X order 
        else if (x0 < z0) {
            i1 = 0;
            j1 = 1;
            k1 = 0;
            i2 = 0;
            j2 = 1;
            k2 = 1;
        } // Y Z X order 
        else {
            i1 = 0;
            j1 = 1;
            k1 = 0;
            i2 = 1;
            j2 = 1;
            k2 = 0;
        } // Y X Z order 
    }
    // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z), 
    // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and 
    // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where 
    // c = 1/6.
    var x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords 
    var y1 = y0 - j1 + G3;
    var z1 = z0 - k1 + G3;
    var x2 = x0 - i2 + 2.0 * G3; // Offsets for third corner in (x,y,z) coords 
    var y2 = y0 - j2 + 2.0 * G3;
    var z2 = z0 - k2 + 2.0 * G3;
    var x3 = x0 - 1.0 + 3.0 * G3; // Offsets for last corner in (x,y,z) coords 
    var y3 = y0 - 1.0 + 3.0 * G3;
    var z3 = z0 - 1.0 + 3.0 * G3;
    // Work out the hashed gradient indices of the four simplex corners 
    var ii = i & 255;
    var jj = j & 255;
    var kk = k & 255;
    var gi0 = this.perm[ii + this.perm[jj + this.perm[kk]]] % 12;
    var gi1 = this.perm[ii + i1 + this.perm[jj + j1 + this.perm[kk + k1]]] % 12;
    var gi2 = this.perm[ii + i2 + this.perm[jj + j2 + this.perm[kk + k2]]] % 12;
    var gi3 = this.perm[ii + 1 + this.perm[jj + 1 + this.perm[kk + 1]]] % 12;
    // Calculate the contribution from the four corners 
    var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0;
    if (t0 < 0) n0 = 0.0;
    else {
        t0 *= t0;
        n0 = t0 * t0 * this.dot(this.grad3[gi0], x0, y0, z0);
    }
    var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1;
    if (t1 < 0) n1 = 0.0;
    else {
        t1 *= t1;
        n1 = t1 * t1 * this.dot(this.grad3[gi1], x1, y1, z1);
    }
    var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2;
    if (t2 < 0) n2 = 0.0;
    else {
        t2 *= t2;
        n2 = t2 * t2 * this.dot(this.grad3[gi2], x2, y2, z2);
    }
    var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3;
    if (t3 < 0) n3 = 0.0;
    else {
        t3 *= t3;
        n3 = t3 * t3 * this.dot(this.grad3[gi3], x3, y3, z3);
    }
    // Add contributions from each corner to get the final noise value. 
    // The result is scaled to stay just inside [-1,1] 
    return 32.0 * (n0 + n1 + n2 + n3);
};

var s = Snap('#mysvg'),
    i,
    j,
    k = 0,
    u,
    _x = 40,
    _y = 40,
    _z,
    noise = new SimplexNoise();

for (i = 0; i < 50; i += 1) {
    for (j = 0; j < 40; j += 1) {
        k += 1;

_x += Math.sin(k) * i / 10;
        _y += Math.cos(k) * j / 8;
        _z = 1 + (noise.noise(_x, _y) / 2);

u = s.select('#plus').use();
        u.attr({
            transform: 'translate(' + _x + ', ' + _y + ') scale(' + _z + ')'
        });

s.select('#mesh').append(u);

_x += 40;
    }
    _x = 40;
    _y += 40;
}

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Source: http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf

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Source: http://staffwww.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf

随机生成SVG面孔（头像）

three.js随机生成3D条形图 | 柱状图

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