Replace boost::mt19937 with std::mt19937

Available since C++11 and already used in the codebase.

Ref: #8210
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

source/graphics/ObjectBase.cpp

@@ -29,8 +29,6 @@
 #include "lib/timer.h"
 #include "maths/MathUtil.h"
 
-#include <boost/random/uniform_int_distribution.hpp>
-
 namespace
 {
 /**
@@ -594,7 +592,7 @@ std::set<CStr> CObjectBase::CalculateRandomRemainingSelections(rng_t& rng, const
 
 				// Choose a random number in the interval [0..totalFreq) to choose one of the variants.
 				// If the diversity is "none", force 0 to return the first valid variant.
-				int randNum = diversity == CObjectManager::VariantDiversity::NONE ? 0 : boost::random::uniform_int_distribution<int>(0, totalFreq-1)(rng);
+				int randNum = diversity == CObjectManager::VariantDiversity::NONE ? 0 : std::uniform_int_distribution<int>(0, totalFreq - 1)(rng);
 				for (size_t i = 0; i < grp->size(); ++i)
 				{
 					randNum -= (allZero ? 1 : (*grp)[i].m_Frequency);

source/graphics/ObjectBase.h

@@ -28,9 +28,9 @@ class CObjectManager;
 class CXeromyces;
 class XMBElement;
 
-#include <boost/random/mersenne_twister.hpp>
 #include <map>
 #include <memory>
+#include <random>
 #include <set>
 #include <unordered_set>
 #include <vector>
@@ -185,7 +185,7 @@ private:
 	// A low-quality RNG like rand48 causes visible non-random patterns (particularly
 	// in large grids of the same actor with consecutive seeds, e.g. forests),
 	// so use a better one that appears to avoid those patterns
-	using rng_t = boost::mt19937;
+	using rng_t = std::mt19937;
 	std::set<CStr> CalculateRandomRemainingSelections(rng_t& rng, const std::vector<std::set<CStr>>& initialSelections) const;
 
 	/**

source/graphics/ParticleEmitterType.cpp

@@ -40,12 +40,10 @@
 #include "renderer/backend/Sampler.h"
 
 #include <algorithm>
-#include <boost/random/uniform_real_distribution.hpp>
 #include <cmath>
 #include <cstddef>
 #include <map>
 
-
 /**
  * Interface for particle state variables, which get evaluated for each newly
  * constructed particle.
@@ -133,7 +131,7 @@ public:
 
 	virtual float Compute(CParticleEmitterType& type, CParticleEmitter&)
 	{
-		return boost::random::uniform_real_distribution<float>(m_Min, m_Max)(type.m_Manager.m_RNG);
+		return std::uniform_real_distribution<float>(m_Min, m_Max)(type.m_Manager.m_RNG);
 	}
 
 	virtual float Min(CParticleEmitterType&)

source/graphics/ParticleManager.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2019 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -21,8 +21,8 @@
 #include "graphics/ParticleEmitter.h"
 #include "graphics/ParticleEmitterType.h"
 
-#include <boost/random/mersenne_twister.hpp>
 #include <list>
+#include <random>
 #include <unordered_map>
 
 class SceneCollector;
@@ -55,7 +55,7 @@ public:
 	Status ReloadChangedFile(const VfsPath& path);
 
 	/// Random number generator shared between all particle emitters.
-	boost::mt19937 m_RNG;
+	std::mt19937 m_RNG;
 
 private:
 	float m_CurrentTime;

source/maths/tests/test_Sqrt.h

@@ -20,11 +20,9 @@
 #include "lib/types.h"
 #include "maths/Sqrt.h"
 
-#include <boost/random/mersenne_twister.hpp>
-#include <boost/random/uniform_int_distribution.hpp>
-#include <boost/random/variate_generator.hpp>
 #include <cmath>
 #include <cstddef>
+#include <random>
 
 class TestSqrt : public CxxTest::TestSuite
 {
@@ -78,13 +76,12 @@ public:
 		// Test with some random u64s, to make sure the output agrees with floor(sqrt(double))
 		// (TODO: This might be making non-portable assumptions about sqrt(double))
 
-		boost::mt19937 rng;
-		boost::random::uniform_int_distribution<u64> ints(0, (u64)-1);
-		boost::variate_generator<boost::mt19937&, boost::random::uniform_int_distribution<u64>> gen(rng, ints);
+		std::mt19937 rng;
+		std::uniform_int_distribution<u64> ints(0, (u64)-1);
 
 		for (size_t i = 0; i < 1024; ++i)
 		{
-			u64 n = gen();
+			u64 n = ints(rng);
 			s(n, static_cast<u64>(sqrt(static_cast<double>(n))));
 		}
 	}

source/simulation2/components/tests/test_RangeManager.h

@@ -22,9 +22,7 @@
 #include "simulation2/components/ICmpPosition.h"
 #include "simulation2/components/ICmpVision.h"
 
-#include <boost/random/mersenne_twister.hpp>
-#include <boost/random/uniform_real_distribution.hpp>
-
+#include <random>
 #include <optional>
 
 class MockVisionRgm : public ICmpVision
@@ -175,11 +173,11 @@ public:
 		{ CMessagePositionChanged msg(100, true, entity_pos_t::FromInt(348), entity_pos_t::FromInt(83), entity_angle_t::Zero()); cmp->HandleMessage(msg, false); }
 		cmp->Verify();
 
-		boost::mt19937 rng;
+		std::mt19937 rng;
 		for (size_t i = 0; i < 1024; ++i)
 		{
-			double x = boost::random::uniform_real_distribution<double>(0.0, 512.0)(rng);
-			double z = boost::random::uniform_real_distribution<double>(0.0, 512.0)(rng);
+			double x = std::uniform_real_distribution<double>(0.0, 512.0)(rng);
+			double z = std::uniform_real_distribution<double>(0.0, 512.0)(rng);
 			{ CMessagePositionChanged msg(100, true, entity_pos_t::FromDouble(x), entity_pos_t::FromDouble(z), entity_angle_t::Zero()); cmp->HandleMessage(msg, false); }
 			cmp->Verify();
 		}