/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2010 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
 * 
 * Deliantra is free software: you can redistribute it and/or modify it under
 * the terms of the Affero GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the Affero GNU General Public License
 * and the GNU General Public License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * The authors can be reached via e-mail to <support@deliantra.net>
 */

#include "noise.h"

noise_gen::noise_gen (uint32_t seed)
{
  seedable_rand_gen rng (seed);

  for (int i = 0; i < 256; ++i)
    {
      for (int j = 0; j < 2; ++j)
        rvec [i][j] = rng () - 0.5f;

      // normalise
      float mag = 1.f / sqrtf (rvec [i][0] * rvec [i][0] + rvec [i][1] * rvec [i][1]);

      rvec [i][0] *= mag;
      rvec [i][1] *= mag;
    }

  rvmap [0].seed (rng);
  rvmap [1].seed (rng);
}

float
noise_gen::noise (float x, float y)
{
  int ix = floorf (x); float fx = x - ix;
  int iy = floorf (y); float fy = y - iy;

  float v = 0;

  for (int j = -1; j <= 2; ++j)
    for (int i = -1; i <= 2; ++i)
      {
        float Ax = fx - i;
        float Ay = fy - j;

        float d  = Ax * Ax + Ay * Ay;

        if (d < 4)
          {
            int h = rvmap [0](ix + i) ^ rvmap [1](iy + j);
            float *G = rvec [h & 0xff];

            float t1 = 1 - d / 4;
            float t2 = t1 * t1;
            float t4 = t2 * t2;

            float p = (4 * t1 - 3) * t4;
            v += (Ax * G[0] + Ay * G[1]) * p;
          }
      }

  return clamp (v * 2, -.9999999f, .9999999f);
}

frac_gen::frac_gen (float hurst_expo, float lacunarity)
: h (hurst_expo), lac (lacunarity), noise_gen (0)
{
  float exsum = 0;

  for (int i = 0; i < MAX_OCTAVES; ++i)
    {
      ex [i] = powf (lac, -h * i);
      exsum += ex [i];
      fbm_mul [i] = 0.5f / (exsum * 0.75f); // .75f is a heuristic
      rot [i].set (0.4488f * i);
    }
}

float
frac_gen::fBm (float x, float y, int octaves)
{
  float v = 0.f;

  for (int i = 0; i < octaves; ++i)
    {
      rot [i](x, y);
      
      v += noise (x + i, y) * ex [i];

      x *= lac;
      y *= lac;
    }

  return clamp (v * fbm_mul [octaves - 1] + 0.5f, 0.f, .9999999f);
}

float
frac_gen::turbulence (float x, float y, int octaves)
{
  float v = 0.f;

  for (int i = 0; i < octaves; ++i)
    {
      rot [i](x, y);

      v += fabsf (noise (x + i, y)) * ex [i];

      x *= lac;
      y *= lac;
    }

  return clamp (v * fbm_mul [octaves - 1] * 2.f, 0.f, .9999999f);
}

float
frac_gen::multifractal (float x, float y, int octaves, float offset)
{
  float v = 1.f;

  for (int i = 0; i < octaves; ++i)
    {
      rot [i](x, y);

      v *= noise (x, y) * ex [i] + offset;

      x *= lac;
      y *= lac;
    }

  return clamp (v * 0.5f, 0.f, .9999999f);
}

float
frac_gen::heterofractal (float x, float y, int octaves, float offset)
{
  float v = noise (x, y) + offset;
  int i;

  for (i = 1; i < octaves; ++i)
    {
      rot [i](x, y);

      x *= lac;
      y *= lac;

      v += v * (noise (x, y) * ex [i] + offset);
    }

  return v / powf (2., octaves);
}

float
frac_gen::hybridfractal (float x, float y, int octaves, float offset, float gain)
{
  float v = (noise (x, y) + offset) * ex [0];
  float weight = v;
  int i;

  for (i = 1; i < octaves; ++i)
    {
      rot [i](x, y);

      x *= lac;
      y *= lac;

      min_it (weight, 1.f);

      float sig = (noise (x, y) + offset) * ex [i];
      v += weight * sig;
      weight *= gain * sig;
    }

  return clamp (v * 0.5f + 0.5f, 0.f, .9999999f);
}

// http://www.gamasutra.com/view/feature/3098/a_realtime_procedural_universe_.php?page=2
float
frac_gen::terrain (float x, float y, int octaves)
{
  float v = 0.f;

  for (int i = 0; i < octaves; ++i)
    {
      rot[i] (x, y);

      v += noise (x + i, y) * ex [i];

      x *= lac;
      y *= lac;
    }

  v *= fbm_mul [octaves - 1];

  return v <= 0.f ? - powf (-v, 0.7f) : powf (v, 1. + noise (x, y) * v);
}

float
frac_gen::terrain2 (float x, float y, int octaves)
{
  float a = fBm (x, y, octaves);
  float b = ridgedmultifractal (x, y, octaves, 1, 8);
  float fade = fBm (x + 10.3, y + 10.3, octaves);

  const float width = 0.05f;

  if (fade > 0.5f + width)
    return a;
  else if (fade < 0.5f - width)
    return b;

  fade = (fade - 0.5f + width) / (width * 2);

  // sigmoidal curve
  fade = fade * fade * 2 * (1.5f - fade);

  return a * fade + b * (1 - fade);
}

float
frac_gen::ridgedmultifractal (float x, float y, int octaves, float offset, float gain)
{
  float sig = offset - fabsf (noise (x, y));
  sig *= sig;
  float v = sig;

  for (int i = 1; i < octaves; ++i)
    {
      rot [i](x, y);

      x *= lac;
      y *= lac;

      float w = clamp (sig * gain, 0.f, 1.f);

      sig = offset - fabsf (noise (x, y));
      sig *= sig;
      sig *= w;

      v += sig * ex [i];
    }

  return clamp (v * 0.25f, 0.f, .9999999f);
}

#if 0
void hack()
{
  frac_gen gen (0.5, 2);

  int N = 1024;

  printf ("P5 %d %d 255\n", N, N);
  // pmake&&server/deliantra-server >x&&convert -depth 8 -size 512xx512 gray:x x.ppm&& cv x.ppm
  for (int y = 0; y < N; ++y)
    {
      if (!(y&63))fprintf (stderr, "y %d\n", y);//D
    for (int x = 0; x < N; ++x)
      {
        //putc (128 + 128 * gen.noise (x * 0.04, y * 0.04), stdout);
        putc (256 * gen.terrain2 (x * 0.004, y * 0.004, 8), stdout);
        //putc (256 * gen.fBm (x * 0.001, y * 0.001, 3), stdout);
        //putc (256 * gen.turbulence (x * 0.004 - 1, y * 0.004 - 1, 8), stdout);
        //putc (256 * gen.heterofractal (x * 0.008, y * 0.008, 8, -1.1, 2.0), stdout);
        //putc (256 * gen.ridgedmultifractal (x * 0.001, y * 0.001, 32, 1.001, 32), stdout);
      }
    }

  exit (0);
}
#endif