quadrilateralcowboy/idlib/math/Random.h
2020-06-12 14:06:25 -07:00

158 lines
4.6 KiB
C++

/*
===========================================================================
Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.
This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).
Doom 3 Source Code 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 3 of the License, or
(at your option) any later version.
Doom 3 Source Code 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 GNU General Public License
along with Doom 3 Source Code. If not, see <http://www.gnu.org/licenses/>.
In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code. If not, please request a copy in writing from id Software at the address below.
If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
===========================================================================
*/
#ifndef __MATH_RANDOM_H__
#define __MATH_RANDOM_H__
/*
===============================================================================
Random number generator
===============================================================================
*/
class idRandom {
public:
idRandom( int seed = 0 );
void SetSeed( int seed );
int GetSeed( void ) const;
int RandomInt( void ); // random integer in the range [0, MAX_RAND]
int RandomInt( int max ); // random integer in the range [0, max[
float RandomFloat( void ); // random number in the range [0.0f, 1.0f]
float CRandomFloat( void ); // random number in the range [-1.0f, 1.0f]
static const int MAX_RAND = 0x7fff;
private:
int seed;
};
ID_INLINE idRandom::idRandom( int seed ) {
this->seed = seed;
}
ID_INLINE void idRandom::SetSeed( int seed ) {
this->seed = seed;
}
ID_INLINE int idRandom::GetSeed( void ) const {
return seed;
}
ID_INLINE int idRandom::RandomInt( void ) {
seed = 69069 * seed + 1;
return ( seed & idRandom::MAX_RAND );
}
ID_INLINE int idRandom::RandomInt( int max ) {
if ( max == 0 ) {
return 0; // avoid divide by zero error
}
return RandomInt() % max;
}
ID_INLINE float idRandom::RandomFloat( void ) {
return ( RandomInt() / ( float )( idRandom::MAX_RAND + 1 ) );
}
ID_INLINE float idRandom::CRandomFloat( void ) {
return ( 2.0f * ( RandomFloat() - 0.5f ) );
}
/*
===============================================================================
Random number generator
===============================================================================
*/
class idRandom2 {
public:
idRandom2( unsigned long seed = 0 );
void SetSeed( unsigned long seed );
unsigned long GetSeed( void ) const;
int RandomInt( void ); // random integer in the range [0, MAX_RAND]
int RandomInt( int max ); // random integer in the range [0, max]
float RandomFloat( void ); // random number in the range [0.0f, 1.0f]
float CRandomFloat( void ); // random number in the range [-1.0f, 1.0f]
static const int MAX_RAND = 0x7fff;
private:
unsigned long seed;
static const unsigned long IEEE_ONE = 0x3f800000;
static const unsigned long IEEE_MASK = 0x007fffff;
};
ID_INLINE idRandom2::idRandom2( unsigned long seed ) {
this->seed = seed;
}
ID_INLINE void idRandom2::SetSeed( unsigned long seed ) {
this->seed = seed;
}
ID_INLINE unsigned long idRandom2::GetSeed( void ) const {
return seed;
}
ID_INLINE int idRandom2::RandomInt( void ) {
seed = 1664525L * seed + 1013904223L;
return ( (int) seed & idRandom2::MAX_RAND );
}
ID_INLINE int idRandom2::RandomInt( int max ) {
if ( max == 0 ) {
return 0; // avoid divide by zero error
}
return ( RandomInt() >> ( 16 - idMath::BitsForInteger( max ) ) ) % max;
}
ID_INLINE float idRandom2::RandomFloat( void ) {
unsigned long i;
seed = 1664525L * seed + 1013904223L;
i = idRandom2::IEEE_ONE | ( seed & idRandom2::IEEE_MASK );
return ( ( *(float *)&i ) - 1.0f );
}
ID_INLINE float idRandom2::CRandomFloat( void ) {
unsigned long i;
seed = 1664525L * seed + 1013904223L;
i = idRandom2::IEEE_ONE | ( seed & idRandom2::IEEE_MASK );
return ( 2.0f * ( *(float *)&i ) - 3.0f );
}
#endif /* !__MATH_RANDOM_H__ */