random.hpp

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/* Copyright (c) 2026 Otto Link. Distributed under the terms of the GNU General
   Public License. The full license is in the file LICENSE, distributed with
   this software. */
#pragma once
#include <cstddef>
#include <cstdint>
 
namespace hmap
{
 
float fast_hash32_to_unit_float(unsigned int seed, size_t k);
 
uint64_t splitmix64(uint64_t x);
 
float splitmix64_to_unit_float(unsigned int seed, size_t k);
 
float uniform01(uint64_t h);
 
// === PdfSampler class ===
 
class PdfSampler
{
public:
  PdfSampler(const std::vector<float> &pdf, uint32_t seed);
 
  float sample();
 
  std::vector<float> sample(size_t nb_samples);
 
private:
  std::vector<float>                    cdf;
  std::mt19937                          generator;
  std::uniform_real_distribution<float> distribution{0.f, 1.f};
};
 
} // namespace hmap