include/cinder/Rand.h

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/*
 Copyright (c) 2010, The Barbarian Group
 All rights reserved.

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

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

 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 HOLDER 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)
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*/

#pragma once

#include <random>
#include "cinder/Vector.h"

namespace cinder {  
    
class Rand {
 public:
    Rand()
        : mBase( 214u ), mHaveNextNextGaussian( false )
    {}
    
    Rand( unsigned long seed )
        : mBase( seed ), mHaveNextNextGaussian( false )
    {}

    void seed( unsigned long seedValue );
    
    bool nextBool()
    {
        return mBase() & 1;
    }
    
    int32_t nextInt()
    {
        return mBase();
    }

    uint32_t nextUint()
    {
        return mBase();
    }
    
    int32_t nextInt( int32_t v )
    {
        if( v <= 0 ) return 0;
        return mBase() % v;
    }

    uint32_t nextUint( uint32_t v )
    {
        if( v == 0 ) return 0;
        return mBase() % v;
    }
    
    int32_t nextInt( int32_t a, int32_t b )
    {
        return nextInt( b - a ) + a;
    }
    
    float nextFloat()
    {
        return mFloatGen(mBase);
    }
    
    float nextFloat( float v )
    {
        return mFloatGen(mBase) * v;
    }
    
    float nextFloat( float a, float b )
    {
        return mFloatGen(mBase) * ( b - a ) + a;
    }
    
    float posNegFloat( float a, float b )
    {
        if( nextBool() )
            return nextFloat( a, b );
        else
            return -nextFloat( a, b );
    }
    
    Vec3f nextVec3f()
    {
        float phi = nextFloat( (float)M_PI * 2.0f );
        float costheta = nextFloat( -1.0f, 1.0f );
        
        float rho = math<float>::sqrt( 1.0f - costheta * costheta ); 
        float x = rho * math<float>::cos( phi );
        float y = rho * math<float>::sin( phi );
        float z = costheta;
        
        return Vec3f( x, y, z );
    }

    Vec2f nextVec2f( )
    {
        float theta = nextFloat( (float)M_PI * 2.0f );
        return Vec2f( math<float>::cos( theta ), math<float>::sin( theta ) );
    }
    
    float nextGaussian()
    {
        if( mHaveNextNextGaussian ) {
            mHaveNextNextGaussian = false;
            return mNextNextGaussian;
        }
        else {
            float v1, v2, s;
            do {
                v1 = 2.0f * nextFloat() - 1.0f;
                v2 = 2.0f * nextFloat() - 1.0f;

                s = v1 * v1 + v2 * v2;
            }
            while( s >= 1.0f || s == 0.0f );

            float m = math<float>::sqrt(-2.0f * math<float>::log(s)/s);
            
            mNextNextGaussian       = v2 * m;
            mHaveNextNextGaussian   = true;

            return v1 * m;
        }
    }    
    
    // STATICS
    static void randomize();
    
    static void randSeed( unsigned long seedValue );
    
    static bool randBool()
    {
        return sBase() & 1;
    }
    
    static int32_t randInt()
    {
        return sBase();
    }

    static uint32_t randUint()
    {
        return sBase();
    }
    
    static int32_t randInt( int32_t v )
    {
        if( v <= 0 ) return 0;
        else return sBase() % v;
    }

    static uint32_t randUint( uint32_t v )
    {
        if( v == 0 ) return 0;
        else return sBase() % v;
    }
    
    static int32_t randInt( int32_t a, int32_t b )
    {
        return randInt( b - a ) + a;
    }
    
    static float randFloat()
    {
        return sFloatGen(sBase);
    }
    
    static float randFloat( float v )
    {
        return sFloatGen(sBase) * v;
    }
    
    static float randFloat( float a, float b )
    {
        return sFloatGen(sBase) * ( b - a ) + a;
    }
    
    static float randPosNegFloat( float a, float b )
    {
        if( randBool() )
            return randFloat( a, b );
        else
            return -randFloat( a, b );
    }
    
    static Vec3f randVec3f()
    {
        float phi = randFloat( (float)M_PI * 2.0f );
        float costheta = randFloat( -1.0f, 1.0f );
        
        float rho = math<float>::sqrt( 1.0f - costheta * costheta ); 
        float x = rho * math<float>::cos( phi );
        float y = rho * math<float>::sin( phi );
        float z = costheta;
        
        return Vec3f( x, y, z );
    }

    static Vec2f randVec2f()
    {
        float theta = randFloat( (float)M_PI * 2.0f );
        return Vec2f( math<float>::cos( theta ), math<float>::sin( theta ) );
    }
    
    static float randGaussian() 
    {
        static bool  sHaveNextNextGaussian = false;
        static float sNextNextGaussian;

        if( sHaveNextNextGaussian ) {
            sHaveNextNextGaussian = false;
            return sNextNextGaussian;
        }
        else {
            float v1, v2, s;
            do {
                v1 = 2.0f * sFloatGen(sBase) - 1.0f;
                v2 = 2.0f * sFloatGen(sBase) - 1.0f;

                s = v1 * v1 + v2 * v2;
            }
            while( s >= 1.0f || s == 0.0f );

            float m = math<float>::sqrt(-2.0f * math<float>::log(s)/s);

            sNextNextGaussian       = v2 * m;
            sHaveNextNextGaussian   = true;
            
            return v1 * m;
        }
    }
    
  private:
    std::mt19937 mBase;
    std::uniform_real_distribution<float>   mFloatGen;  
    float   mNextNextGaussian;    
    bool    mHaveNextNextGaussian;
    
    static std::mt19937 sBase;
    static std::uniform_real_distribution<float> sFloatGen;
};

inline void randSeed( unsigned long seedValue ) { Rand::randSeed( seedValue ); }

inline bool randBool() { return Rand::randBool(); }

inline int32_t randInt() { return Rand::randInt(); }

inline int32_t randInt( int32_t v ) { return Rand::randInt( v ); }

inline int32_t randInt( int32_t a, int32_t b ) { return Rand::randInt( a, b ); }

inline float randFloat() { return Rand::randFloat(); }

inline float randFloat( float v ) { return Rand::randFloat( v ); }

inline float randFloat( float a, float b ) { return Rand::randFloat( a, b ); }

inline float randPosNegFloat( float a, float b ) { return Rand::randPosNegFloat( a, b ); }

inline Vec3f randVec3f() { return Rand::randVec3f(); }

inline Vec2f randVec2f() { return Rand::randVec2f(); }

inline float randGaussian() { return Rand::randGaussian(); }    

} // namespace cinder