/*
 * 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>
 */

#ifndef NOISE_H_
#define NOISE_H_

#include "global.h"

template<int N, typename T = uint8_t>
struct permutation
{
  T pmap [N];

  template<class generator>
  void seed (generator &rng)
  {
    for (int i = 0; i < N; ++i)
      pmap [i] = i;

    // fisher-yates to randomly perturb
    for (int i = N; --i; )
      ::swap (pmap [i], pmap [::rmg_rndm (i + 1)]);
  }

  T operator ()(T v)
  {
    return pmap [v & (N - 1)];
  }
};

struct noise_gen
{
  permutation<256, uint8_t> rvmap[2];
  float rvec [256][2]; // random unit vectors

  noise_gen (uint32_t seed);
  float noise (float x, float y);
};

struct rotate
{
  float s, c;

  void set (float angle)
  {
    s = sinf (angle);
    c = cosf (angle);
  }

  void operator ()(float &x, float &y) const
  {
    float xr = x * c - y * s;
    float yr = x * s + y * c;

    x = xr;
    y = yr;
  }
};

struct frac_gen
: noise_gen
{
  enum { MAX_OCTAVES = 64 };

  float h, lac, ex [MAX_OCTAVES];
  float fbm_mul [MAX_OCTAVES];
  rotate rot [MAX_OCTAVES];

  frac_gen (float hurst_expo = .5f, float lacunarity = 2.f);

  float fBm (float x, float y, int octaves);
  float turbulence (float x, float y, int octaves);
  float multifractal (float x, float y, int octaves, float offset = 1);
  float heterofractal (float x, float y, int octaves, float offset = 1);
  float hybridfractal (float x, float y, int octaves, float offset = 1, float gain = 1);
  float terrain (float x, float y, int octaves);
  float terrain2 (float x, float y, int octaves);
  float ridgedmultifractal (float x, float y, int octaves, float offset = 1, float gain = 8);
};

#endif