49 lines
1.1 KiB
C++
49 lines
1.1 KiB
C++
|
// This code is in the public domain -- castanyo@yahoo.es
|
||
|
|
||
|
#include <nvmath/Random.h>
|
||
|
#include <time.h>
|
||
|
|
||
|
using namespace nv;
|
||
|
|
||
|
|
||
|
/// Get a random seed based on the current time.
|
||
|
uint Rand::randomSeed()
|
||
|
{
|
||
|
return (uint)time(NULL);
|
||
|
}
|
||
|
|
||
|
|
||
|
void MTRand::initialize( uint32 seed )
|
||
|
{
|
||
|
// Initialize generator state with seed
|
||
|
// See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
|
||
|
// In previous versions, most significant bits (MSBs) of the seed affect
|
||
|
// only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto.
|
||
|
uint32 *s = state;
|
||
|
uint32 *r = state;
|
||
|
int i = 1;
|
||
|
*s++ = seed & 0xffffffffUL;
|
||
|
for( ; i < N; ++i )
|
||
|
{
|
||
|
*s++ = ( 1812433253UL * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffUL;
|
||
|
r++;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
|
||
|
void MTRand::reload()
|
||
|
{
|
||
|
// Generate N new values in state
|
||
|
// Made clearer and faster by Matthew Bellew (matthew.bellew@home.com)
|
||
|
uint32 *p = state;
|
||
|
int i;
|
||
|
for( i = N - M; i--; ++p )
|
||
|
*p = twist( p[M], p[0], p[1] );
|
||
|
for( i = M; --i; ++p )
|
||
|
*p = twist( p[M-N], p[0], p[1] );
|
||
|
*p = twist( p[M-N], p[0], state[0] );
|
||
|
|
||
|
left = N, next = state;
|
||
|
}
|
||
|
|