Random.h

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/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * This program 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 2 of the License, or (at your
 * option) any later version.
 *
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef TRINITYCORE_RANDOM_H
#define TRINITYCORE_RANDOM_H
 
#include "Define.h"
#include "Duration.h"
#include <concepts>
#include <limits>
 
/* Return a random number in the range min..max. */
TC_COMMON_API int32 irand(int32 min, int32 max);
 
/* Return a random number in the range min..max (inclusive). */
TC_COMMON_API uint32 urand(uint32 min, uint32 max);
 
/* Return a random millisecond value between min and max seconds. Functionally equivalent to urand(min*IN_MILLISECONDS, max*IN_MILLISECONDS). */
TC_COMMON_API uint32 urandms(uint32 min, uint32 max);
 
/* Return a random number in the range 0 .. UINT32_MAX. */
TC_COMMON_API uint32 rand32();
 
/* Return a random time in the range min..max (up to millisecond precision). Only works for values where millisecond difference is a valid uint32. */
TC_COMMON_API Milliseconds randtime(Milliseconds min, Milliseconds max);
 
/* Return a random number in the range min..max */
TC_COMMON_API float frand(float min, float max);
 
/* Return a random float from 0.0 to 1.0 (exclusive). */
TC_COMMON_API float rand_norm();
 
/* Return a random float from 0.0 to 100.0 (exclusive). */
TC_COMMON_API float rand_chance();
 
/* Return a random number in the range 0..count (exclusive) with each value having a different chance of happening */
TC_COMMON_API uint32 urandweighted(size_t count, double const* chances);
 
/* Return true if a random roll fits in the specified chance (range 0-100). */
template <std::floating_point T>
inline bool roll_chance(T chance)
{
    return chance > rand_chance();
}
 
/* Return true if a random roll fits in the specified chance (range 0-100). */
template <std::signed_integral T>
inline bool roll_chance(T chance)
{
    return chance > irand(0, 99);
}
 
/* Return true if a random roll fits in the specified chance (range 0-100). */
template <std::unsigned_integral T>
inline bool roll_chance(T chance)
{
    return chance > urand(0, 99);
}
 
/*
* Wrapper satisfying UniformRandomNumberGenerator concept for use in <random> algorithms
*/
class RandomEngine
{
public:
    typedef uint32 result_type;
 
    static constexpr result_type min() { return std::numeric_limits<result_type>::min(); }
    static constexpr result_type max() { return std::numeric_limits<result_type>::max(); }
    result_type operator()() const { return rand32(); }
};
 
struct PseudoRandomDistributionState
{
    float AccumulateChance(float progress) { return _progress += progress; }
    void Reset() { _progress = 0; }
 
private:
    float _progress = 0.0f;
};
 
/* Return true if a random roll fits in the specified chance (range 0-100) using pseudo random distribution that minimizes long good/bad luck streaks. */
TC_COMMON_API bool roll_chance(float chance, PseudoRandomDistributionState& state);
 
#endif // TRINITYCORE_RANDOM_H