Torque3D/Engine/source/math/mRandom.h

//-----------------------------------------------------------------------------
// Copyright (c) 2012 GarageGames, LLC
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//-----------------------------------------------------------------------------

#ifndef _MRANDOM_H_
#define _MRANDOM_H_

#ifndef _PLATFORMASSERT_H_
#include "platform/platformAssert.h"
#endif


//--------------------------------------
/// Base class for random number generators
class MRandomGenerator
{
protected:
   MRandomGenerator() {}
   S32  mSeed;

public:
   virtual ~MRandomGenerator() {}
   
   void setSeed();
   S32  getSeed() { return mSeed; }
   virtual void setSeed(S32 s) = 0;

   virtual U32 randI( void ) = 0;      ///< 0..2^31 random number generator
   virtual F32  randF( void );         ///< 0.0 .. 1.0 F32 random number generator
   S32 randI(S32 i, S32 n);            ///< i..n integer random number generator
   F32 randF(F32 i, F32 n);            ///< i..n F32 random number generator
};


//--------------------------------------
inline F32 MRandomGenerator::randF()
{
   // default: multiply by 1/(2^31)
   return  F32(randI()) * (1.0f/2147483647.0f);
}

inline S32 MRandomGenerator::randI(S32 i, S32 n)
{
   AssertFatal(i<=n, "MRandomGenerator::randi: inverted range.");
   return (S32)(i + (randI() % (n - i + 1)) );
}

inline F32 MRandomGenerator::randF(F32 i, F32 n)
{
   AssertFatal(i<=n, "MRandomGenerator::randf: inverted range.");
   return (i + (n - i) * randF());
}


//--------------------------------------
/// Linear Congruential Method, the "minimal standard generator"
///
/// Fast, farly good random numbers (better than using rand)
///
/// @author Park & Miller, 1988, Comm of the ACM, 31(10), pp. 1192-1201
class MRandomLCG : public MRandomGenerator
{
protected:
   static const S32 msQuotient;
   static const S32 msRemainder;

public:
   MRandomLCG();
   MRandomLCG(S32 s);
   virtual ~MRandomLCG() {}

   static void setGlobalRandSeed(U32 seed);

   void setSeed(S32 s);
//   using MRandomGenerator::randI;
    S32 randI(S32 i, S32 n);            ///< i..n integer generator

   U32 randI( void );

};

// Solution to "using" problem.
inline S32 MRandomLCG::randI(S32 i, S32 n)
{
    return( MRandomGenerator::randI(i,n) );
}


//--------------------------------------
/// Fast, very good random numbers
///
/// Period = 2^249
///
/// Kirkpatrick, S., and E. Stoll, 1981; A Very Fast Shift-Register
///       Sequence Random Number Generator, Journal of Computational Physics,
/// V. 40.
///
/// Maier, W.L., 1991; A Fast Pseudo Random Number Generator,
/// Dr. Dobb's Journal, May, pp. 152 - 157
class MRandomR250: public MRandomGenerator
{
private:
   U32 mBuffer[250];
   S32 mIndex;

public:
   MRandomR250();
   MRandomR250(S32 s);
   virtual ~MRandomR250() {}

   void setSeed(S32 s);
// using MRandomGenerator::randI;
   U32 randI();
};


typedef MRandomLCG MRandom;

extern MRandomLCG gRandGen;


#endif //_MRANDOM_H_