/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2010,2011 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 <blitz/tinyvec.h>
#include <blitz/tinyvec-et.h>

#include "global.h"

typedef blitz::TinyVector<float,2> vec2d;
typedef blitz::TinyVector<float,3> vec3d;

vec2d
inline floor (vec2d v)
{
  return vec2d (fastfloor (v[0]), fastfloor (v[1]));
}

vec3d
inline floor (vec3d v)
{
  return vec3d (fastfloor (v[0]), fastfloor (v[1]), fastfloor (v[2]));
}

vec2d
inline pow (vec2d v, vec2d p)
{
  return vec2d (pow (v[0], p[0]), pow (v[1], p[1]));
}

/////////////////////////////////////////////////////////////////////////////

// various s-shaped curves, smooth to, first, or second derivative
// used for smooth interpolation from 0..1

// linear
template<typename T>
inline T
sigmoid0 (T x)
{
  return x;
}

// 3x²-2x³
template<typename T>
inline T
sigmoid1 (T x)
{
  return (3 - 2 * x) * x * x;
}

// 6x⁵ - 15x⁴ + 10x³
template<typename T>
inline T
sigmoid2 (T x)
{
#ifdef MORE_PARALLELITY
  float x2 = x  * x;
  float x4 = x2 * x2;

  return (6 * x4 + 10 * x2) * x - 15 * x4;
#endif

  // simple horner
  return ((6 * x - 15) * x + 10) * x * x * x;
}

// blend between a and b
// c is the control function - if lower than ca
// then return a, if higher than cb, return b
template<typename T, typename U>
inline T
blend (T a, T b, U c, U ca, U cb, U weight (U) = sigmoid1)
{
  if (c <= ca) return a;
  if (c >= cb) return b;

  U w = weight ((c - ca) / (cb - ca));
  return (U(1) - w) * a + w * b;
}

// blend between a and b
// c is the control function - if lower than -c_w
// then return a, if higher than +c_w then b.
template<typename T, typename U>
inline T
blend0 (T a, T b, U c, U c_w, U weight (U) = sigmoid1)
{
  return blend<T,U> (a, b, c, -c_w, c_w, weight);
}

template<class vec_t, int a, int b>
struct rotate_nn
{
  typename vec_t::T_numtype s, c;

  void set (typename vec_t::T_numtype angle)
  {
    s = sin (angle);
    c = cos (angle);
  }

  void operator ()(vec_t &P) const
  {
    vec_t o = P;

    P[a] = o[a] * c - o[b] * s;
    P[b] = o[a] * s + o[b] * c;
  }
};

template<class vec_t>
struct rotate_xy : rotate_nn<vec_t, 0, 1>
{
};

template<class vec_t>
struct rotate_xz : rotate_nn<vec_t, 0, 2>
{
};

template<class vec_t>
struct rotate_yz : rotate_nn<vec_t, 1, 2>
{
};

/////////////////////////////////////////////////////////////////////////////

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

  void seed (seedable_rand_gen &rng);

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

/////////////////////////////////////////////////////////////////////////////

template<class vec_t>
struct noise_gen_base
{
  permutation<256, uint8_t> rvmap[vec_t::numElements + 1];

  typedef typename vec_t::T_numtype value_t;

  void seed (seedable_rand_gen &rng);
  void seed (seed_t seed);

  value_t operator ()(vec_t P, uint32_t seed = 0) func_pure;
};

template<class vec_t>
struct noise_gen;

// modelled after 2d/3d kensler noise without projection
template<>
struct noise_gen<vec2d>
: noise_gen_base<vec2d>
{
  static value_t abs_avg() { return 0.2231; } // avg(abs(noise))
};

template<>
struct noise_gen<vec3d>
: noise_gen_base<vec3d>
{
  static vec3d::T_numtype abs_avg() { return 0.415; } // avg(abs(noise))

  using noise_gen_base<vec3d>::operator ();

  // noise projected on a surface with normal n
  vec2d::T_numtype operator() (vec3d P, vec3d N, uint32_t seed = 0) func_pure;
};

typedef noise_gen<vec2d> noise2d;
typedef noise_gen<vec3d> noise3d;

/////////////////////////////////////////////////////////////////////////////

template<class vec_t>
struct frac_gen
: noise_gen<vec_t>
{
  enum { MAX_OCTAVES = 32 };

  typedef typename vec_t::T_numtype value_t;

  int octaves;
  value_t h, lac, ex[MAX_OCTAVES];
  value_t fbm_mul[MAX_OCTAVES];
  rotate_xy<vec_t> rot[MAX_OCTAVES];

  frac_gen (int octaves = 3, value_t lacunarity = 2, value_t hurst_expo = .5, uint32_t seed = 0);

  value_t noise (vec_t P, uint32_t seed = 0) func_pure
  {
    return operator() (P, seed);
  }

  value_t fBm (vec_t P) func_pure;
  value_t turbulence (vec_t P) func_pure;
  value_t multifractal (vec_t P, value_t offset = 1) func_pure;
  value_t heterofractal (vec_t P, value_t offset = 1) func_pure;
  value_t hybridfractal (vec_t P, value_t offset = 1, value_t gain = 1) func_pure;
  value_t ridgedmultifractal (vec_t P, value_t offset = 1, value_t gain = 8) func_pure;
  value_t billowfractal (vec_t P, value_t offset = 1, value_t gain = 2) func_pure;
  value_t terrain (vec_t P) func_pure;
  value_t terrain2 (vec_t P) func_pure;
};

typedef frac_gen<vec2d> frac2d;
typedef frac_gen<vec3d> frac3d;

/////////////////////////////////////////////////////////////////////////////

template<typename T, typename U>
T
inline border_blend (T a, T b, vec2d P, U N, U W)
{
  U border = W; // within n places of the border

  min_it (border,     P [0]);
  min_it (border, N - P [0]);
  min_it (border,     P [1]);
  min_it (border, N - P [1]);

  return blend (a, b,border, U(0), W);
}

#endif