// title: Perlin Noise

initialState = {
  x: 64,
  y: 64,
  size: 64,
  zoom: 0.1,
  base_x: 0,
  base_y: 0,
  t: 0
}

update = (state, input) => {
  //if (state.t===0)
  state.t += 1
  if (input.up) state.base_y -= 0.1
  if (input.down) state.base_y += 0.1
  if (input.left) state.base_x -= 0.1
  if (input.right) state.base_x += 0.1
  if (input.start) {
    state.zoom -= 0.01
    state.base_x += 0.5
    state.base_y += 0.5
  }
  if (input.select) {
    state.zoom += 0.01
    state.base_x -= 0.5
    state.base_y -= 0.5
  }
  if (input.a) state.size += 1
  if (input.b) state.size -= 1
}

draw = state => {
  clear()
  rectStroke(state.x - state.size/2 - 1, state.y - state.size/2 - 1, state.size + 2, state.size + 2, 1)
  for (let row of range(0, state.size)) {
    let line = state.y - state.size/2 + row
    for (let col of range(0, state.size)) {
      let pix = state.x - state.size/2 + col
      let n = Math.round(PerlinNoise.noise(pix * state.zoom + state.base_x, 
                                           line * state.zoom + state.base_y,
                                           1.2 * state.zoom) * 8 + state.t/30) % 8
      let o = Math.round(PerlinNoise.noise((pix * state.zoom + state.base_x) * 4, 
                                           (line * state.zoom + state.base_y) * 4,
                                           1.2 * state.zoom) * 8 + state.t/30) % 8

      if (n>3) n = 7 - n
      if (o>3) o = 7 - o
      let val = Math.round((4/5) * n) + ((1/15) * o)
      setPixel(pix, line, o+n)
    }
  }
  
  
}
// This is a port of Ken Perlin's Java code. The
// original Java code is at http://cs.nyu.edu/%7Eperlin/noise/.
// Note that in this version, a number from 0 to 1 is returned.
// Taken from http://asserttrue.blogspot.com/2011/12/perlin-noise-in-javascript_31.html
var PerlinNoise = new function() {

this.noise = function(x, y, z) {

   var p = new Array(512)
   var permutation = [ 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
   ];
   for (var i=0; i < 256 ; i++) 
 p[256+i] = p[i] = permutation[i]; 

      var X = Math.floor(x) & 255,                  // FIND UNIT CUBE THAT
          Y = Math.floor(y) & 255,                  // CONTAINS POINT.
          Z = Math.floor(z) & 255;
      x -= Math.floor(x);                                // FIND RELATIVE X,Y,Z
      y -= Math.floor(y);                                // OF POINT IN CUBE.
      z -= Math.floor(z);
      var    u = fade(x),                                // COMPUTE FADE CURVES
             v = fade(y),                                // FOR EACH OF X,Y,Z.
             w = fade(z);
      var A = p[X  ]+Y, AA = p[A]+Z, AB = p[A+1]+Z,      // HASH COORDINATES OF
          B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;      // THE 8 CUBE CORNERS,

      return scale(lerp(w, lerp(v, lerp(u, grad(p[AA  ], x  , y  , z   ),  // AND ADD
                                     grad(p[BA  ], x-1, y  , z   )), // BLENDED
                             lerp(u, grad(p[AB  ], x  , y-1, z   ),  // RESULTS
                                     grad(p[BB  ], x-1, y-1, z   ))),// FROM  8
                     lerp(v, lerp(u, grad(p[AA+1], x  , y  , z-1 ),  // CORNERS
                                     grad(p[BA+1], x-1, y  , z-1 )), // OF CUBE
                             lerp(u, grad(p[AB+1], x  , y-1, z-1 ),
                                     grad(p[BB+1], x-1, y-1, z-1 )))));
   }
   function fade(t) { return t * t * t * (t * (t * 6 - 15) + 10); }
   function lerp( t, a, b) { return a + t * (b - a); }
   function grad(hash, x, y, z) {
      var h = hash & 15;                      // CONVERT LO 4 BITS OF HASH CODE
      var u = h<8 ? x : y,                 // INTO 12 GRADIENT DIRECTIONS.
             v = h<4 ? y : h==12||h==14 ? x : z;
      return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
   } 
   function scale(n) { return (1 + n)/2; }
}