Windows Phone: Are you Game? Part 1

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework;

using Harlinn.WindowsPhone.XNA.Engine.Extensions;

namespace Harlinn.WindowsPhone.XNA.Engine.Imaging
{
  public partial class XNAImage
  {
    static public double Noise(double x, double y, double z)
    {
      int X = (int)Math.Floor(x) & 255;
      int Y = (int)Math.Floor(y) & 255;
      int Z = (int)Math.Floor(z) & 255;
      x -= Math.Floor(x);
      y -= Math.Floor(y);
      z -= Math.Floor(z);
      double u = Fade(x);
      double v = Fade(y);
      double w = Fade(z);

      int A = p[X] + Y;
      int AA = p[A] + Z;
      int AB = p[A + 1] + Z;
      int B = p[X + 1] + Y;
      int BA = p[B] + Z; 
      int BB = p[B + 1] + Z;

      return Lerp(w, Lerp(v, Lerp(u, Grad(p[AA], x, y, z),
                                     Grad(p[BA], x - 1, y, z)),
                             Lerp(u, Grad(p[AB], x, y - 1, z),
                                     Grad(p[BB], x - 1, y - 1, z))),
                     Lerp(v, Lerp(u, Grad(p[AA + 1], x, y, z - 1),
                                     Grad(p[BA + 1], x - 1, y, z - 1)),
                             Lerp(u, Grad(p[AB + 1], x, y - 1, z - 1),
                                     Grad(p[BB + 1], x - 1, y - 1, z - 1))));
    }

    static double Fade(double t) 
    { 
      return t * t * t * (t * (t * 6 - 15) + 10); 
    }
    static double Lerp(double t, double a, double b) 
    { 
      return a + t * (b - a); 
    }
    static double Grad(int hash, double x, double y, double z)
    {
      int h = hash & 15;
      double u = h < 8 ? x : y,
             v = h < 4 ? y : h == 12 || h == 14 ? x : z;
      return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
    }

    static readonly int[] p = new int[512];

    static readonly int[] 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
    };

    static XNAImage()
    {
      for (int i = 0; i < 256; i++) p[256 + i] = p[i] = permutation[i];
    }

    /// <summary>
    /// computes a 3D perlin noise and returns a value in the range -1..1
    /// </summary>
    /// <param name="x"></param>
    /// <param name="y"></param>
    /// <param name="z"></param>
    /// <param name="amplitude"></param>
    /// <param name="frequency"></param>
    /// <param name="persistence"></param>
    /// <param name="octaves"></param>
    /// <returns></returns>
    public static double Compute(double x, double y, double z, double amplitude, double frequency, double persistence, int octaves)
    {
      double noiseValue = 0;
      for (int i = 0; i < octaves; i++)
      {
        noiseValue += Noise(x * frequency, y * frequency, z * frequency) * amplitude;
        frequency *= 2; 
        amplitude *= persistence;
      }

      noiseValue /= octaves;
      return noiseValue;
    }

    public static int NoiceToColor(double noiseValue)
    {
      if (noiseValue < 0)
      {
        noiseValue = 0;
      }
      else if (noiseValue > 1)
      {
        noiseValue = 1;
      }

      return (int)(noiseValue * 255);
    }

    public static int GetColorRegular(double noiseValue)
    {
      return (int)((noiseValue + 1) * (255.0 / 2));
    }


    public void PerlinNoise(double amplitude, double frequency, double persistence, int octaves, double zStart)
    {
      for (int x = 0; x < width; x++)
      {
        for (int y = 0; y < height; y++)
        {
          int r = NoiceToColor(Compute(x, y, zStart, amplitude, frequency, persistence, octaves));
          int g = NoiceToColor(Compute(x, y, zStart + 100, amplitude, frequency, persistence, octaves));
          int b = NoiceToColor(Compute(x, y, zStart + 200, amplitude, frequency, persistence, octaves));

          pixels[y * width + x] = (255 << 24) + (r << 16) + (g << 8) + b;
        }
      }
    }



    


  }
}