OSimplexNoise

(function() {
  var __imul = Math.imul ? Math.imul : function(a, b) {
    return (a * (b >>> 16) << 16) + a * (b & 65535) | 0;
  };

  function assert(truth) {
    if (!truth) {
      throw Error('Assertion failed');
    }
  }

  function main() {
    var noiser = new OSimplexNoise();
    noiser.setSeed1();
    tileset.src = 'tileset.png';
    tileset.onload = function() {
      var can = document.getElementById('app');
      var ctx = can.getContext('2d');
      can.width = 200;
      can.height = 200;

      for (var x = 0, count1 = can.width; x < count1; x = x + 1 | 0) {
        for (var y = 0, count = can.height; y < count; y = y + 1 | 0) {
          var a = noiser.noise2D(x / 100 | 0, y / 100 | 0);
          a = (a + 1) * 128;
          var b = a | 0;
          ctx.fillStyle = 'rgb(' + b.toString() + ', ' + b.toString() + ', ' + b.toString() + ')';
          ctx.fillRect(x, y, 1, 1);
        }
      }

      return;

      for (var y1 = 0, count3 = in_List.count(map); y1 < count3; y1 = y1 + 1 | 0) {
        for (var x1 = 0, count2 = in_List.count(in_List.get(map, y1)); x1 < count2; x1 = x1 + 1 | 0) {
          ctx.drawImage(tileset, __imul(in_List.get(in_List.get(map, y1), x1), CELL_SIZE), 0, CELL_SIZE, CELL_SIZE, __imul(x1, CELL_SIZE), __imul(y1, CELL_SIZE), CELL_SIZE, CELL_SIZE);
        }
      }
    };
  }

  function OSimplexNoise() {
    this.seed = 0;
    this.randArray = null;
    this.seed = 0;
    this.randArray = new Int8Array(256);
  }

  OSimplexNoise.prototype.setSeed1 = function() {
    for (var i = 0; i < 256; i = i + 1 | 0) {
      this.randArray[i] = Math.random() * 256;
    }
  };

  OSimplexNoise.prototype.extrapolate2D = function(xsb, ysb, dx, dy) {
    var gradients = new Int8Array([5, 2, 2, 5, -5, 2, -2, 5, 5, -2, 2, -5, -5, -2, -2, -5]);
    var idx = this.randArray[this.randArray[xsb & 255] + ysb & 255] & 14;
    return gradients[idx] * dx + gradients[idx + 1] * dy;
  };

  OSimplexNoise.prototype.noise2D = function(x, y) {
    x = +x;
    y = +y;
    var stretchOffset = (x + y) * OSimplexNoise.STRETCH_CONSTANT_2D;
    var xs = x + stretchOffset;
    var ys = y + stretchOffset;
    var xsb = Math.floor(xs) | 0;
    var ysb = Math.floor(ys) | 0;
    var squishOffset = (xsb + ysb | 0) * OSimplexNoise.SQUISH_CONSTANT_2D;
    var xb = xsb + squishOffset;
    var yb = ysb + squishOffset;
    var xins = xs - xsb;
    var yins = ys - ysb;
    var inSum = xins + yins;
    var dx0 = x - xb;
    var dy0 = y - yb;
    var dxExt = 0;
    var dyExt = 0;
    var xsvExt = 0;
    var ysvExt = 0;
    var value = 0;
    var dx1 = dx0 - 1 * OSimplexNoise.SQUISH_CONSTANT_2D;
    var dy1 = dy0 - 0 - OSimplexNoise.SQUISH_CONSTANT_2D;
    var attn1 = 2 - dx1 * dx1 - dy1 * dy1;

    if (attn1 > 0) {
      attn1 *= attn1;
      value += attn1 * attn1 * this.extrapolate2D(xsb + 1 | 0, ysb + 0 | 0, dx1, dy1);
    }

    var dx2 = dx0 - 0 * OSimplexNoise.SQUISH_CONSTANT_2D;
    var dy2 = dy0 - 1 - OSimplexNoise.SQUISH_CONSTANT_2D;
    var attn2 = 2 - dx2 * dx2 - dy2 * dy2;

    if (attn2 > 0) {
      attn2 *= attn2;
      value += attn2 * attn2 * this.extrapolate2D(xsb + 0 | 0, ysb + 1 | 0, dx2, dy2);
    }

    if (inSum <= 1) {
      var zins = 1 - inSum;

      if (zins > xins || zins > yins) {
        if (xins > yins) {
          xsvExt = xsb + 1 | 0;
          ysvExt = ysb - 1 | 0;
          dxExt = dx0 - 1;
          dyExt = dy0 + 1;
        }

        else {
          xsvExt = xsb - 1 | 0;
          ysvExt = ysb + 1 | 0;
          dxExt = dx0 + 1;
          dyExt = dy0 - 1;
        }
      }

      else {
        xsvExt = xsb + 1 | 0;
        ysvExt = ysb + 1 | 0;
        dxExt = dx0 - 1 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
        dyExt = dy0 - 1 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
      }
    }

    else {
      var zins1 = 2 - inSum;

      if (zins1 < xins || zins1 < yins) {
        if (xins > yins) {
          xsvExt = xsb + 2 | 0;
          ysvExt = ysb + 0 | 0;
          dxExt = dx0 - 2 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
          dyExt = dy0 + 0 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
        }

        else {
          xsvExt = xsb + 0 | 0;
          ysvExt = ysb + 2 | 0;
          dxExt = dx0 + 0 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
          dyExt = dy0 - 2 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
        }
      }

      else {
        dxExt = dx0;
        dyExt = dy0;
        xsvExt = xsb;
        ysvExt = ysb;
      }

      xsb = xsb + 1 | 0;
      ysb = ysb + 1 | 0;
      dx0 -= 1 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
      dy0 -= 1 - 2 * OSimplexNoise.SQUISH_CONSTANT_2D;
    }

    var attn0 = 2 - dx0 * dx0 - dy0 * dy0;

    if (attn0 > 0) {
      attn0 *= attn0;
      value += attn0 * attn0 * this.extrapolate2D(xsb, ysb, dx0, dy0);
    }

    var attnExt = 2 - dxExt * dxExt - dyExt * dyExt;

    if (attnExt > 0) {
      attnExt *= attnExt;
      value += attnExt * attnExt * this.extrapolate2D(xsvExt, ysvExt, dxExt, dyExt);
    }

    return value / OSimplexNoise.NORM_CONSTANT_2D;
  };

  var in_List = {};

  in_List.get = function(self, index) {
    assert(0 <= index && index < in_List.count(self));
    return self[index];
  };

  in_List.count = function(self) {
    return self.length;
  };

  var map = [[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], [1, 7, 3, 6, 1, 1, 1, 1, 1, 1, 1, 7, 3, 6, 1], [1, 2, 0, 4, 1, 1, 1, 1, 1, 1, 7, 16, 0, 4, 1], [1, 2, 0, 4, 1, 1, 1, 1, 1, 7, 16, 0, 0, 4, 1], [1, 9, 15, 17, 3, 6, 1, 1, 7, 16, 0, 0, 0, 4, 1], [1, 1, 9, 15, 0, 4, 1, 7, 20, 5, 5, 5, 5, 8, 1], [1, 1, 1, 2, 0, 4, 1, 2, 4, 1, 1, 1, 1, 1, 1], [1, 1, 1, 2, 0, 4, 1, 2, 4, 1, 1, 1, 1, 1, 1], [1, 1, 1, 2, 0, 0, 0, 0, 8, 1, 1, 1, 1, 1, 1], [1, 1, 1, 2, 0, 4, 1, 1, 1, 1, 1, 7, 6, 1, 1], [1, 1, 1, 2, 0, 17, 3, 3, 3, 3, 3, 16, 4, 1, 1], [1, 7, 3, 5, 15, 0, 0, 18, 5, 5, 5, 5, 19, 6, 1], [1, 9, 15, 1, 2, 5, 15, 4, 1, 1, 1, 1, 2, 4, 1], [1, 1, 10, 1, 10, 1, 9, 8, 1, 1, 1, 1, 9, 8, 1], [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]];
  var CELL_SIZE = 16;
  var tileset = new Image();

  // (1/sqrt(2+1)-1)/2
  OSimplexNoise.STRETCH_CONSTANT_2D = -0.2113248654051871;

  // (sqrt(2+1)-1)/2
  OSimplexNoise.SQUISH_CONSTANT_2D = 0.36602540378443865;
  OSimplexNoise.NORM_CONSTANT_2D = 47;

  main();
})();