Random.h

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// Copyright (c) 2018-2021 www.open3d.org
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#pragma once

#include <mutex>
#include <random>

#include "open3d/utility/Logging.h"

namespace open3d {
namespace utility {
namespace random {

void Seed(const int seed);

std::mt19937* GetEngine();

std::mutex* GetMutex();

uint32_t RandUint32();

template <typename T>
class UniformIntGenerator {
public:
    UniformIntGenerator(const T low, const T high) : distribution_(low, high) {
        if (low < 0) {
            utility::LogError("low must be > 0, but got {}.", low);
        }
        if (low >= high) {
            utility::LogError("low must be < high, but got low={} and high={}.",
                              low, high);
        }
    }

    T operator()() {
        std::lock_guard<std::mutex> lock(*GetMutex());
        return distribution_(*GetEngine());
    }

protected:
    std::uniform_int_distribution<T> distribution_;
};

template <typename T>
class UniformRealGenerator {
public:
    UniformRealGenerator(const T low = 0.0, const T high = 1.0)
        : distribution_(low, high) {
        if (low >= high) {
            utility::LogError("low must be < high, but got low={} and high={}.",
                              low, high);
        }
    }

    T operator()() {
        std::lock_guard<std::mutex> lock(*GetMutex());
        return distribution_(*GetEngine());
    }

protected:
    std::uniform_real_distribution<T> distribution_;
};

template <typename T>
class NormalGenerator {
public:
    NormalGenerator(const T mean = 0.0, const T stddev = 1.0)
        : distribution_(mean, stddev) {
        if (stddev <= 0) {
            utility::LogError("stddev must be > 0, but got {}.", stddev);
        }
    }

    T operator()() {
        std::lock_guard<std::mutex> lock(*GetMutex());
        return distribution_(*GetEngine());
    }

protected:
    std::normal_distribution<T> distribution_;
};

}  // namespace random
}  // namespace utility
}  // namespace open3d