random_generator.h

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/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
*                                                                    \      *
* All rights reserved.                                                      *
*                                                                           *
* This program is free software; you can redistribute it and/or modify      *
* it under the terms of the GNU General Public License as published by      *
* the Free Software Foundation; either version 2 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 (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
*                                                                           *
****************************************************************************/

#ifndef __VCG_RandomGenerator
#define __VCG_RandomGenerator

#include <vcg/math/base.h>

namespace vcg {
namespace math {

class RandomGenerator
{

// construction
public:

    RandomGenerator(){}

    virtual ~RandomGenerator()
    {}

// public methods
public:

    virtual void initialize(unsigned int seed)=0;

    virtual unsigned int generate(unsigned int limit)=0;

    virtual double generate01()=0;

    virtual double generate01closed()=0;

    virtual double generate01open()=0;
    virtual double generateRange(double minV, double maxV) { return minV+(maxV-minV)*generate01(); }

};

template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GenerateBarycentricUniform(GeneratorType &rnd)
{
  vcg::Point3<ScalarType>  interp;
    interp[1] = rnd.generate01();
    interp[2] = rnd.generate01();
    if(interp[1] + interp[2] > 1.0)
    {
        interp[1] = 1.0 - interp[1];
        interp[2] = 1.0 - interp[2];
        }

    assert(interp[1] + interp[2] <= 1.0);
    interp[0]=1.0-(interp[1] + interp[2]);
    return interp;
}

template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GeneratePointInBox3Uniform(GeneratorType &rnd, const Box3<ScalarType> &bb)
{
  return Point3<ScalarType>(
      (ScalarType) rnd.generateRange(double(bb.min[0]),double(bb.max[0])),
      (ScalarType) rnd.generateRange(double(bb.min[1]),double(bb.max[1])),
      (ScalarType) rnd.generateRange(double(bb.min[2]),double(bb.max[2]))
      );
}

template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GeneratePointOnUnitSphereUniform(GeneratorType &rnd)
{
  vcg::Point3<ScalarType> p;
  double x,y,s;
  do
  {
    x = 2.0*rnd.generate01()-1.0;
    y = 2.0*rnd.generate01()-1.0;
    s = x*x+y*y;
  } while (s>1);
  p[0]= ScalarType(2 * x * sqrt(1-s));
  p[1]= ScalarType(2 * y * sqrt(1-s));
  p[2]= ScalarType(1-2*s);
  return p;
}

template <class ScalarType, class GeneratorType>
vcg::Point3<ScalarType> GeneratePointInUnitBallUniform(GeneratorType &rnd)
{
  vcg::Point3<ScalarType> p;
  while(1)
  {
    p.Import(Point3d(0.5-rnd.generate01(),0.5-rnd.generate01(),0.5-rnd.generate01()));
    if(SquaredNorm(p)<=0.25){
      p*=2;
      return p;
    }
  }
}


class SubtractiveRingRNG : public RandomGenerator
{

// private data member
private:

    // Subtractive Ring RNG status variables
    unsigned int _M_table[55];
    size_t _M_index1;
    size_t _M_index2;

// construction
public:

    // ctor
    SubtractiveRingRNG(int default_seed=161803398u)
    {
        initialize(default_seed);
    }

    virtual ~SubtractiveRingRNG()
    {}

// public methods
public:

    void initialize(unsigned int seed)
    {
        unsigned int __k = 1;
        _M_table[54] = seed;
        size_t __i;
        for (__i = 0; __i < 54; __i++)
        {
            size_t __ii = (21 * (__i + 1) % 55) - 1;
            _M_table[__ii] = __k;
            __k = seed - __k;
            seed = _M_table[__ii];
        }
        for (int __loop = 0; __loop < 4; __loop++)
        {
            for (__i = 0; __i < 55; __i++)
                _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55];
        }
        _M_index1 = 0;
        _M_index2 = 31;
    }

    unsigned int generate(unsigned int limit= 0xffffffffu)
    {
        _M_index1 = (_M_index1 + 1) % 55;
        _M_index2 = (_M_index2 + 1) % 55;
        _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2];
        return _M_table[_M_index1] % limit;
    }

    double generate01()
    {
        const unsigned int lmt = 0xffffffffu;
        unsigned int number = generate(lmt);
        return static_cast<double>(number) / static_cast<double>(lmt);
    }

    double generate01closed()
    {
        const unsigned int lmt = 0xffffffffu;
        unsigned int number = generate(lmt);
        return static_cast<double>(number) / static_cast<double>(0xfffffffEu);
    }

    double generate01open()
    {
        const unsigned int lmt = 0xffffffffu;
        unsigned int number = generate(lmt);
        return (static_cast<double>(number) + 0.5) * (1.0/static_cast<double>(lmt));
    }

};

class MarsenneTwisterRNG : public RandomGenerator
{

// definitions
private:

    static const int N = 624;
    static const int M = 397;
    static const unsigned int MATRIX_A = 0x9908b0dfu;   // constant vector a
    static const unsigned int UPPER_MASK = 0x80000000u; // most significant w-r bits
    static const unsigned int LOWER_MASK = 0x7fffffffu; // least significant r bits

// private data member
private:

    // Improved Marsenne-Twister RNG status variables
    unsigned int mt[N]; // the array for the state vector
    int mti;

// construction
public:

    // ctor
    MarsenneTwisterRNG()
    {
        initialize(5489u);
    }

    MarsenneTwisterRNG(unsigned int seed)
    {
        initialize(seed);
    }

    virtual ~MarsenneTwisterRNG()
    {}


// public methods
public:

    void initialize(unsigned int seed)
    {
        mt[0]= seed & 0xffffffffu;
        for (mti=1; mti<N; mti++)
        {
            mt[mti] = (1812433253u * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
            /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
            /* In the previous versions, MSBs of the seed affect   */
            /* only MSBs of the array mt[].                        */
            /* 2002/01/09 modified by Makoto Matsumoto             */
            mt[mti] &= 0xffffffffu;
            /* for >32 bit machines */
        }
    }

    void initializeByArray(unsigned int init_key[], int key_length)
    {
        int i, j, k;
        initialize(19650218u);
        i=1; j=0;
        k = (N>key_length ? N : key_length);
        for (; k; k--)
        {
            mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525u)) + init_key[j] + j; /* non linear */
            mt[i] &= 0xffffffffu; /* for WORDSIZE > 32 machines */
            i++; j++;

            if (i>=N)
            {
                mt[0] = mt[N-1];
                i=1;
            }

            if (j>=key_length) j=0;
        }

        for (k=N-1; k; k--)
        {
            mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941u)) - i; /* non linear */
            mt[i] &= 0xffffffffu; /* for WORDSIZE > 32 machines */
            i++;
            if (i>=N)
            {
                mt[0] = mt[N-1];
                i=1;
            }
        }

        mt[0] = 0x80000000u; /* MSB is 1; assuring non-zero initial array */
    }

    unsigned int generate(unsigned int limit)
    {
      return generate()%limit;
    }

    unsigned int generate()
    {
        unsigned int y;
        static unsigned int mag01[2]={0x0u, MATRIX_A};
        /* mag01[x] = x * MATRIX_A  for x=0,1 */

        if (mti >= N) // generate N words at one time
        {
            int kk;

            for (kk=0;kk<N-M;kk++)
            {
                y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
                mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1u];
            }

            for (;kk<N-1;kk++)
            {
                y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
                mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1u];
            }

            y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
            mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1u];

            mti = 0;
        }

        y = mt[mti++];

        /* Tempering */
        y ^= (y >> 11);
        y ^= (y << 7) & 0x9d2c5680u;
        y ^= (y << 15) & 0xefc60000u;
        y ^= (y >> 18);

        return y;
    }

    double generate01closed()
    {
        return generate()*(1.0/4294967295.0);
    }

    double generate01()
    {
        return generate()*(1.0/4294967296.0);
    }

    double generate01open()
    {
        return (((double)generate()) + 0.5)*(1.0/4294967296.0);
    }

    template <class PointType>
    void generateBarycentric(PointType &p){
        p[1] = this->generate01();
        p[2] = this->generate01();

        if(p[1] + p[2] > 1.0){
            p[1] = 1.0 - p[1];
            p[2] = 1.0 - p[2];
        }
        p[0]=1.0-(p[1] + p[2]);
    }
}; // end class MarsenneTwisterRNG

/* Returns a value with normal distribution with mean m, standard deviation s
 *
 * It implements the Polar form of the Box-Muller Transformation
 * A transformation which transforms from a two-dimensional continuous uniform distribution
 * to a two-dimensional bivariate normal distribution
 * with mean m, standard deviation s
 */
inline double box_muller(RandomGenerator &generator, double m, double s) /* normal random variate generator */
{ /* */
  double x1, x2, w, y1;
  static double y2;
  static int use_last = 0;
  static RandomGenerator *last_generator = 0;
  if(last_generator != &generator)
    use_last = 0;
  last_generator = &generator;
  if (use_last){ /* use value from previous call */
    y1 = y2;
    use_last = 0;
  } else {
    do {
      x1 = 2.0 * generator.generate01closed() - 1.0;
      x2 = 2.0 * generator.generate01closed() - 1.0;
      w = x1 * x1 + x2 * x2;
    } while ( w >= 1.0 );
    w = sqrt( (-2.0 * log( w ) ) / w );
    y1 = x1 * w;
    y2 = x2 * w;
   use_last = 1;
  }
  return( m + y1 * s );
}
} // end namespace math
} // end namespace vcg



/*
   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

     1. Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

     2. Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.

     3. The names of its contributors may not be used to endorse or promote
        products derived from this software without specific prior written
        permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#endif /* __VCG_RandomGenerator */