/*
 * 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.
 *
 */

(function(global){
    var module = global.noise = {};

    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.seed = 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.seed(0);

    /*
     for(var i=0; i<256; i++) {
     perm[i] = perm[i + 256] = p[i];
     gradP[i] = gradP[i + 256] = grad3[perm[i] % 12];
     }*/

    // 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 = 0.5 - 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 = 0.5 - x1*x1-y1*y1-z1*z1;
        if(t1<0) {
            n1 = 0;
        } else {
            t1 *= t1;
            n1 = t1 * t1 * gi1.dot3(x1, y1, z1);
        }
        var t2 = 0.5 - x2*x2-y2*y2-z2*z2;
        if(t2<0) {
            n2 = 0;
        } else {
            t2 *= t2;
            n2 = t2 * t2 * gi2.dot3(x2, y2, z2);
        }
        var t3 = 0.5 - 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);

    };

    // ##### Perlin noise stuff

    function fade(t) {
        return t*t*t*(t*(t*6-15)+10);
    }

    function lerp(a, b, t) {
        return (1-t)*a + t*b;
    }

    // 2D Perlin Noise
    module.perlin2 = function(x, y) {
        // Find unit grid cell containing point
        var X = Math.floor(x), Y = Math.floor(y);
        // Get relative xy coordinates of point within that cell
        x = x - X; y = y - Y;
        // Wrap the integer cells at 255 (smaller integer period can be introduced here)
        X = X & 255; Y = Y & 255;

        // Calculate noise contributions from each of the four corners
        var n00 = gradP[X+perm[Y]].dot2(x, y);
        var n01 = gradP[X+perm[Y+1]].dot2(x, y-1);
        var n10 = gradP[X+1+perm[Y]].dot2(x-1, y);
        var n11 = gradP[X+1+perm[Y+1]].dot2(x-1, y-1);

        // Compute the fade curve value for x
        var u = fade(x);

        // Interpolate the four results
        return lerp(
            lerp(n00, n10, u),
            lerp(n01, n11, u),
            fade(y));
    };

    // 3D Perlin Noise
    module.perlin3 = function(x, y, z) {
        // Find unit grid cell containing point
        var X = Math.floor(x), Y = Math.floor(y), Z = Math.floor(z);
        // Get relative xyz coordinates of point within that cell
        x = x - X; y = y - Y; z = z - Z;
        // Wrap the integer cells at 255 (smaller integer period can be introduced here)
        X = X & 255; Y = Y & 255; Z = Z & 255;

        // Calculate noise contributions from each of the eight corners
        var n000 = gradP[X+  perm[Y+  perm[Z  ]]].dot3(x,   y,     z);
        var n001 = gradP[X+  perm[Y+  perm[Z+1]]].dot3(x,   y,   z-1);
        var n010 = gradP[X+  perm[Y+1+perm[Z  ]]].dot3(x,   y-1,   z);
        var n011 = gradP[X+  perm[Y+1+perm[Z+1]]].dot3(x,   y-1, z-1);
        var n100 = gradP[X+1+perm[Y+  perm[Z  ]]].dot3(x-1,   y,   z);
        var n101 = gradP[X+1+perm[Y+  perm[Z+1]]].dot3(x-1,   y, z-1);
        var n110 = gradP[X+1+perm[Y+1+perm[Z  ]]].dot3(x-1, y-1,   z);
        var n111 = gradP[X+1+perm[Y+1+perm[Z+1]]].dot3(x-1, y-1, z-1);

        // Compute the fade curve value for x, y, z
        var u = fade(x);
        var v = fade(y);
        var w = fade(z);

        // Interpolate
        return lerp(
            lerp(
                lerp(n000, n100, u),
                lerp(n001, n101, u), w),
            lerp(
                lerp(n010, n110, u),
                lerp(n011, n111, u), w),
            v);
    };

})(this);