godot/core/math/random_pcg.h

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/*  random_pcg.h                                                         */
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#ifndef RANDOM_PCG_H
#define RANDOM_PCG_H

#include "core/math/math_defs.h"

#include "thirdparty/misc/pcg.h"

class RandomPCG {
	pcg32_random_t pcg;
	uint64_t current_seed; // seed with this to get the same state

public:
	static const uint64_t DEFAULT_SEED = 12047754176567800795U;
	static const uint64_t DEFAULT_INC = PCG_DEFAULT_INC_64;
	static const uint64_t RANDOM_MAX = 0xFFFFFFFF;

	RandomPCG(uint64_t p_seed = DEFAULT_SEED, uint64_t p_inc = PCG_DEFAULT_INC_64);

	_FORCE_INLINE_ void seed(uint64_t p_seed) {
		current_seed = p_seed;
		pcg.state = p_seed;
		pcg32_random_r(&pcg); // Force changing internal state to avoid initial 0
	}
	_FORCE_INLINE_ uint64_t get_seed() { return current_seed; }

	void randomize();
	_FORCE_INLINE_ uint32_t rand() {
		current_seed = pcg.state;
		return pcg32_random_r(&pcg);
	}
	_FORCE_INLINE_ double randd() { return (double)rand() / (double)RANDOM_MAX; }
	_FORCE_INLINE_ float randf() { return (float)rand() / (float)RANDOM_MAX; }

	double random(double p_from, double p_to);
	float random(float p_from, float p_to);
	real_t random(int p_from, int p_to) { return (real_t)random((real_t)p_from, (real_t)p_to); }
};

#endif // RANDOM_PCG_H