(function(global){

/*

 * A speed-improved perlin and simplex noise algorithms for 2D.

 *

 * Based on example code by Stefan Gustavson (stegu@itn.liu.se).

 * Optimisations by Peter Eastman (peastman@drizzle.stanford.edu).

 * Better rank ordering method by Stefan Gustavson in 2012.

 * Converted to Javascript by Joseph Gentle.

 *

 * Version 2012-03-09

 *

 * This code was placed in the public domain by its original author,

 * Stefan Gustavson. You may use it as you see fit, but

 * attribution is appreciated.

 *

 */

  var module = global;

​

  function Grad(x, y, z) {

    this.x = x; this.y = y; this.z = z;

  }

  Grad.prototype.dot2 = function(x, y) {

    return this.x*x + this.y*y;

  };

​

  Grad.prototype.dot3 = function(x, y, z) {

    return this.x*x + this.y*y + this.z*z;

  };

​

  var grad3 = [new Grad(1,1,0),new Grad(-1,1,0),new Grad(1,-1,0),new Grad(-1,-1,0),

               new Grad(1,0,1),new Grad(-1,0,1),new Grad(1,0,-1),new Grad(-1,0,-1),

               new Grad(0,1,1),new Grad(0,-1,1),new Grad(0,1,-1),new Grad(0,-1,-1)];

​

  var p = [151,160,137,91,90,15,

  131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,

  190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,

  88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,

  77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,

  102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,

  135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,

  5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,

  223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,

  129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,

  251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,

  49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,

  138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180];

  // To remove the need for index wrapping, double the permutation table length

  var perm = new Array(512);

  var gradP = new Array(512);

​

  // This isn't a very good seeding function, but it works ok. It supports 2^16

  // different seed values. Write something better if you need more seeds.

  module.simplexSeed = function(seed) {

    if(seed > 0 && seed < 1) {

      // Scale the seed out

      seed *= 65536;

    }

​

    seed = Math.floor(seed);

    if(seed < 256) {

      seed |= seed << 8;

    }

​

    for(var i = 0; i < 256; i++) {

      var v;

      if (i & 1) {

        v = p[i] ^ (seed & 255);

      } else {

        v = p[i] ^ ((seed>>8) & 255);

      }

​

      perm[i] = perm[i + 256] = v;

      gradP[i] = gradP[i + 256] = grad3[v % 12];

    }

  };

​

  module.simplexSeed(0);

​

  // Skewing and unskewing factors for 2, 3, and 4 dimensions

  var F2 = 0.5*(Math.sqrt(3)-1);

  var G2 = (3-Math.sqrt(3))/6;

​

  var F3 = 1/3;

  var G3 = 1/6;

​

  // 2D simplex noise

  module.simplex2 = 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 s = (xin+yin)*F2; // Hairy factor for 2D

    var i = Math.floor(xin+s);

    var j = Math.floor(yin+s);

    var t = (i+j)*G2;

    var x0 = xin-i+t; // The x,y distances from the cell origin, unskewed.

    var y0 = yin-j+t;

    // 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) { // lower triangle, XY order: (0,0)->(1,0)->(1,1)

      i1=1; j1=0;

    } else {    // upper triangle, YX order: (0,0)->(0,1)->(1,1)

      i1=0; j1=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 + 2 * G2; // Offsets for last corner in (x,y) unskewed coords

    var y2 = y0 - 1 + 2 * G2;

    // Work out the hashed gradient indices of the three simplex corners

    i &= 255;

    j &= 255;

    var gi0 = gradP[i+perm[j]];

    var gi1 = gradP[i+i1+perm[j+j1]];

    var gi2 = gradP[i+1+perm[j+1]];

    // Calculate the contribution from the three corners

    var t0 = 0.5 - x0*x0-y0*y0;

    if(t0<0) {

      n0 = 0;

    } else {

      t0 *= t0;

      n0 = t0 * t0 * gi0.dot2(x0, y0);  // (x,y) of grad3 used for 2D gradient

    }

    var t1 = 0.5 - x1*x1-y1*y1;

    if(t1<0) {

      n1 = 0;

    } else {

      t1 *= t1;

      n1 = t1 * t1 * gi1.dot2(x1, y1);

    }

    var t2 = 0.5 - x2*x2-y2*y2;

    if(t2<0) {

      n2 = 0;

    } else {

      t2 *= t2;

      n2 = t2 * t2 * gi2.dot2(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 * (n0 + n1 + n2);

  };

​

  // 3D simplex noise

  module.simplex3 = 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 s = (xin+yin+zin)*F3; // Hairy factor for 2D

    var i = Math.floor(xin+s);

    var j = Math.floor(yin+s);

    var k = Math.floor(zin+s);

​

    var t = (i+j+k)*G3;

    var x0 = xin-i+t; // The x,y distances from the cell origin, unskewed.

    var y0 = yin-j+t;

    var z0 = zin-k+t;

​

    // 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; }

      else if(x0 >= z0) { i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; }

      else              { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; }

    } else {

      if(y0 < z0)      { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; }

      else if(x0 < z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; }

      else             { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; }

    }

    // 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

    var y1 = y0 - j1 + G3;

    var z1 = z0 - k1 + G3;

​

    var x2 = x0 - i2 + 2 * G3; // Offsets for third corner

    var y2 = y0 - j2 + 2 * G3;

    var z2 = z0 - k2 + 2 * G3;

​

    var x3 = x0 - 1 + 3 * G3; // Offsets for fourth corner

    var y3 = y0 - 1 + 3 * G3;

    var z3 = z0 - 1 + 3 * G3;

​

    // Work out the hashed gradient indices of the four simplex corners

    i &= 255;

    j &= 255;

    k &= 255;

    var gi0 = gradP[i+   perm[j+   perm[k   ]]];

    var gi1 = gradP[i+i1+perm[j+j1+perm[k+k1]]];

    var gi2 = gradP[i+i2+perm[j+j2+perm[k+k2]]];

    var gi3 = gradP[i+ 1+perm[j+ 1+perm[k+ 1]]];

​

    // Calculate the contribution from the four corners

    var t0 = 0.6 - x0*x0 - y0*y0 - z0*z0;

    if(t0<0) {

      n0 = 0;

    } else {

      t0 *= t0;

      n0 = t0 * t0 * gi0.dot3(x0, y0, z0);  // (x,y) of grad3 used for 2D gradient

    }

    var t1 = 0.6 - x1*x1 - y1*y1 - z1*z1;

    if(t1<0) {

      n1 = 0;

    } else {

      t1 *= t1;

      n1 = t1 * t1 * gi1.dot3(x1, y1, z1);

    }

    var t2 = 0.6 - x2*x2 - y2*y2 - z2*z2;

    if(t2<0) {

      n2 = 0;

    } else {

      t2 *= t2;

      n2 = t2 * t2 * gi2.dot3(x2, y2, z2);

    }

    var t3 = 0.6 - x3*x3 - y3*y3 - z3*z3;

    if(t3<0) {

      n3 = 0;

    } else {

      t3 *= t3;

      n3 = t3 * t3 * gi3.dot3(x3, y3, z3);

    }

    // Add contributions from each corner to get the final noise value.

    // The result is scaled to return values in the interval [-1,1].

    return 32 * (n0 + n1 + n2 + n3);

​

  };

​

})(this);

​

var cols, rows;

var scl = 20;

var w = 2000;

var h = 400;

var zoff = 0;

var inc = 0.1;

var zinc = 0.02;

var start = 0;

var minVal = -10;

var maxVal = 10;

var startInc = 0;

​

function setup() {

  createCanvas(800, 350, WEBGL);

  cols = w / scl;

  rows = h / scl;

}

​

function draw() {

  background(0);

  stroke(255);

  noFill();

  rotateX(PI/3);

  translate(-w/2, -h/2);

  let yoff = -start;

  for (let y = 0; y < rows - 1; y++) {

    let xoff = 0;

    beginShape(TRIANGLE_STRIP);

    for (let x = 0; x < cols; x++) {

      vertex(x*scl, y*scl, map(simplex3(xoff,yoff,zoff), 0, 1, minVal, maxVal));

      vertex(x*scl, (y+1)*scl, map(simplex3(xoff,yoff,zoff), 0, 1, minVal, maxVal));

      xoff += inc;

    }

    yoff += inc;

    endShape();

  }

  zoff += zinc;

  start += startInc;

}