mirror of https://github.com/axmolengine/axmol.git
109 lines
3.0 KiB
C++
109 lines
3.0 KiB
C++
#ifndef _FAST_RNG_H__
|
|
#define _FAST_RNG_H__
|
|
|
|
#include <cmath>
|
|
#include <limits.h>
|
|
|
|
/** A fast more effective seeded random number generator struct, made by kiss rng.
|
|
* It uses a simple algorithm to improve the speed of generating random numbers with a decent quality,
|
|
* Use this if you're planning to generate large amounts of random numbers in a single frame.
|
|
*
|
|
* @since adxe-1.0.0b8
|
|
*/
|
|
struct FastRNG
|
|
{
|
|
const uint32_t RNG_RAND_MAX = std::numeric_limits<uint32_t>::max();
|
|
uint32_t _x = 1;
|
|
uint32_t _y = 2;
|
|
uint32_t _z = 4;
|
|
uint32_t _w = 8;
|
|
uint32_t _carry = 0;
|
|
uint32_t _k = 0;
|
|
uint32_t _m = 0;
|
|
|
|
#ifdef UINT64_C
|
|
uint64_t _seed = 0;
|
|
#else
|
|
uint32_t _seed = 0;
|
|
#endif
|
|
|
|
FastRNG() { seed_rng((uint32_t)time(NULL)); }
|
|
|
|
// initialize this object with a uint32_t seed
|
|
void seed_rng(uint32_t seed)
|
|
{
|
|
_seed = seed;
|
|
_x = seed | 1;
|
|
_y = seed | 2;
|
|
_z = seed | 4;
|
|
_w = seed | 8;
|
|
_carry = 0;
|
|
}
|
|
|
|
#ifdef UINT64_C
|
|
// initialize this object with a uint64_t seed
|
|
void seed_rng_64(uint64_t seed)
|
|
{
|
|
_seed = seed;
|
|
_x = seed | 1;
|
|
_y = seed | 2;
|
|
_z = seed | 4;
|
|
_w = seed | 8;
|
|
_carry = 0;
|
|
}
|
|
#endif
|
|
|
|
// returns a random uint32_t value
|
|
uint32_t rng()
|
|
{
|
|
_x = _x * 69069 + 12345;
|
|
_y ^= _y << 13;
|
|
_y ^= _y >> 17;
|
|
_y ^= _y << 5;
|
|
_k = (_z >> 2) + (_w >> 3) + (_carry >> 2);
|
|
_m = _w + _w + _z + _carry;
|
|
_z = _w;
|
|
_w = _m;
|
|
_carry = _k >> 30;
|
|
return _x + _y + _w;
|
|
}
|
|
|
|
// returns a random integer from min to max
|
|
int32_t range(int32_t min, int32_t max)
|
|
{
|
|
return static_cast<int32_t>(min + rng() / (RNG_RAND_MAX / (max - min)));
|
|
}
|
|
|
|
// returns a random unsigned integer from min to max
|
|
uint32_t rangeu(uint32_t min, uint32_t max)
|
|
{
|
|
return static_cast<uint32_t>(min + rng() / (RNG_RAND_MAX / (max - min)));
|
|
}
|
|
|
|
// returns a random integer from 0 to max
|
|
int32_t max(int32_t max = INT_MAX)
|
|
{
|
|
return static_cast<int32_t>(rng() / static_cast<float>(RNG_RAND_MAX / (max - 0)));
|
|
}
|
|
|
|
// returns a random unsigned integer from 0 to max
|
|
uint32_t maxu(uint32_t max = UINT_MAX) { return static_cast<uint32_t>(0 + rng() / (RNG_RAND_MAX / (max - 0))); }
|
|
|
|
// returns a random float from min to max
|
|
float rangef(float min = -1.0F, float max = 1.0F)
|
|
{
|
|
return min + rng() / static_cast<float>(RNG_RAND_MAX / (max - min));
|
|
}
|
|
|
|
// returns a random float from 0.0 to max
|
|
float maxf(float max) { return rng() / static_cast<float>(RNG_RAND_MAX / (max - 0)); }
|
|
|
|
// returns a random float from 0.0 to 1.0
|
|
float float01() { return rng() / static_cast<float>(RNG_RAND_MAX / (1 - 0)); }
|
|
|
|
// returns either false or true randomly
|
|
bool bool01() { return static_cast<bool>(floor(rng() / static_cast<float>(RNG_RAND_MAX / (2 - 0)))); }
|
|
};
|
|
|
|
#endif // _FAST_RNG_H__
|