use custom std::minstd_rand based RNG for AI

Author: wichern

libs/s25main/ai/aijh/AIConstruction.cpp

@@ -10,13 +10,13 @@
 #include "addons/const_addons.h"
 #include "ai/AIInterface.h"
 #include "ai/aijh/AIPlayerJH.h"
+#include "ai/random.h"
 #include "buildings/noBuildingSite.h"
 #include "buildings/nobBaseMilitary.h"
 #include "buildings/nobBaseWarehouse.h"
 #include "buildings/nobMilitary.h"
 #include "buildings/nobUsual.h"
 #include "helpers/containerUtils.h"
-#include "random/Random.h"
 #include "nodeObjs/noFlag.h"
 #include "nodeObjs/noRoadNode.h"
 #include "gameTypes/BuildingQuality.h"
@@ -467,10 +467,10 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
 
     const Inventory& inventory = aii.GetInventory();
     uint8_t playerId = aii.GetPlayerId();
-    if((RANDOM.Rand(RANDOM_CONTEXT2(playerId), 3) == 0 || inventory.people[Job::Private] < 15)
+    if((AI::randomValue<int>(0, 3) == 0 || inventory.people[Job::Private] < 15)
        && (inventory.goods[GoodType::Stones] > 6 || bldPlanner.GetNumBuildings(BuildingType::Quarry) > 0))
         bld = BuildingType::Guardhouse;
-    if(aijh.getAIInterface().isHarborPosClose(pt, 19) && RANDOM.Rand(RANDOM_CONTEXT2(playerId), 10) != 0
+    if(aijh.getAIInterface().isHarborPosClose(pt, 19) && AI::randomValue<int>(0, 10) != 0
        && aijh.ggs.isEnabled(AddonId::SEA_ATTACK))
     {
         if(aii.CanBuildBuildingtype(BuildingType::Watchtower))
@@ -481,7 +481,7 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
     {
         if(aijh.UpdateUpgradeBuilding() < 0 && bldPlanner.GetNumBuildingSites(biggestBld) < 1
            && (inventory.goods[GoodType::Stones] > 20 || bldPlanner.GetNumBuildings(BuildingType::Quarry) > 0)
-           && RANDOM.Rand(RANDOM_CONTEXT2(playerId), 10) != 0)
+           && AI::randomValue<int>(0, 10) != 0)
         {
             return biggestBld;
         }
@@ -495,7 +495,7 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
         // Prüfen ob Feind in der Nähe
         if(milBld->GetPlayer() != playerId && distance < 35)
         {
-            int randmil = RANDOM.Rand(RANDOM_CONTEXT2(playerId), std::numeric_limits<int>::max());
+            int randmil = AI::randomValue<int>(0, std::numeric_limits<int>::max());
             bool buildCatapult = randmil % 8 == 0 && aii.CanBuildCatapult()
                                  && bldPlanner.GetNumAdditionalBuildingsWanted(BuildingType::Catapult) > 0;
             // another catapult within "min" radius? ->dont build here!

libs/s25main/ai/aijh/AIPlayerJH.cpp

@@ -11,6 +11,7 @@
 #include "RttrForeachPt.h"
 #include "addons/const_addons.h"
 #include "ai/AIEvents.h"
+#include "ai/random.h"
 #include "boost/filesystem/fstream.hpp"
 #include "buildings/noBuildingSite.h"
 #include "buildings/nobHarborBuilding.h"
@@ -26,7 +27,6 @@
 #include "notifications/RoadNote.h"
 #include "notifications/ShipNote.h"
 #include "pathfinding/PathConditionRoad.h"
-#include "random/Random.h"
 #include "nodeObjs/noAnimal.h"
 #include "nodeObjs/noFlag.h"
 #include "nodeObjs/noShip.h"
@@ -40,7 +40,6 @@
 #include <algorithm>
 #include <array>
 #include <memory>
-#include <random>
 #include <stdexcept>
 #include <type_traits>
 
@@ -345,7 +344,7 @@ void AIPlayerJH::PlanNewBuildings(const unsigned gf)
         DistributeGoodsByBlocking(GoodType::Boards, 30);
         DistributeGoodsByBlocking(GoodType::Stones, 50);
         // go to the picked random warehouse and try to build around it
-        int randomStore = RANDOM.Rand(RANDOM_CONTEXT2(playerId), storehouses.size());
+        int randomStore = AI::randomValue<int>(0, storehouses.size());
         auto it = storehouses.begin();
         std::advance(it, randomStore);
         const MapPoint whPos = (*it)->GetPos();
@@ -366,7 +365,7 @@ void AIPlayerJH::PlanNewBuildings(const unsigned gf)
     const std::list<nobMilitary*>& militaryBuildings = aii.GetMilitaryBuildings();
     if(militaryBuildings.empty())
         return;
-    int randomMiliBld = RANDOM.Rand(RANDOM_CONTEXT2(playerId), militaryBuildings.size());
+    int randomMiliBld = AI::randomValue<int>(0, militaryBuildings.size());
     auto it2 = militaryBuildings.begin();
     std::advance(it2, randomMiliBld);
     MapPoint bldPos = (*it2)->GetPos();
@@ -1210,7 +1209,7 @@ void AIPlayerJH::HandleExpedition(const noShip* ship)
         aii.FoundColony(ship);
     else
     {
-        const unsigned offset = RANDOM.Rand(RANDOM_CONTEXT2(playerId), helpers::MaxEnumValue_v<ShipDirection>);
+        const unsigned offset = AI::randomValue<unsigned>(0, helpers::MaxEnumValue_v<ShipDirection>);
         for(auto dir : helpers::EnumRange<ShipDirection>{})
         {
             dir = ShipDirection((rttr::enum_cast(dir) + offset) % helpers::MaxEnumValue_v<ShipDirection>);
@@ -1255,7 +1254,7 @@ void AIPlayerJH::HandleTreeChopped(const MapPoint pt)
 
     UpdateNodesAround(pt, 3);
 
-    if(RANDOM.Rand(RANDOM_CONTEXT2(playerId), 2) == 0)
+    if(AI::randomValue<int>(0, 2) == 0)
         AddMilitaryBuildJob(pt);
     else // if (random % 12 == 0)
         AddBuildJob(BuildingType::Woodcutter, pt);
@@ -1537,7 +1536,7 @@ void AIPlayerJH::TryToAttack()
         // We skip the current building with a probability of limit/numMilBlds
         // -> For twice the number of blds as the limit we will most likely skip every 2nd building
         // This way we check roughly (at most) limit buildings but avoid any preference for one building over an other
-        if(static_cast<unsigned>(RANDOM.Rand(RANDOM_CONTEXT2(playerId), static_cast<int>(numMilBlds))) > limit)
+        if(AI::randomValue<unsigned>(0, numMilBlds) > limit)
             continue;
 
         if(milBld->GetFrontierDistance() == FrontierDistance::Far) // inland building? -> skip it
@@ -1570,7 +1569,7 @@ void AIPlayerJH::TryToAttack()
 
     // shuffle everything but headquarters and harbors without any troops in them
     std::shuffle(potentialTargets.begin() + hq_or_harbor_without_soldiers, potentialTargets.end(),
-                 std::mt19937(RANDOM.Rand(RANDOM_CONTEXT2(playerId), 2048)));
+                 std::mt19937(AI::randomValue<unsigned>(0, 2048)));
 
     // check for each potential attacking target the number of available attacking soldiers
     for(const nobBaseMilitary* target : potentialTargets)
@@ -1704,9 +1703,7 @@ void AIPlayerJH::TrySeaAttack()
     unsigned skip = 0;
     if(searcharoundharborspots.size() > 15)
         skip =
-          std::max<int>(
-            RANDOM.Rand(RANDOM_CONTEXT2(playerId), static_cast<int>(searcharoundharborspots.size() / 15 + 1) * 15), 1)
-          - 1;
+          std::max<int>(AI::randomValue<int>(0, static_cast<int>(searcharoundharborspots.size() / 15 + 1) * 15), 1) - 1;
     for(unsigned i = skip; i < searcharoundharborspots.size() && limit > 0; i++)
     {
         limit--;

libs/s25main/ai/random.cpp

@@ -0,0 +1,16 @@
+// Copyright (C) 2005 - 2025 Settlers Freaks (sf-team at siedler25.org)
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "ai/random.h"
+
+namespace AI {
+
+std::minstd_rand& getRandomGenerator()
+{
+    std::random_device rnd_dev;
+    static std::minstd_rand rng(rnd_dev());
+    return rng;
+}
+
+} // namespace AI

libs/s25main/ai/random.h

@@ -0,0 +1,20 @@
+// Copyright (C) 2005 - 2025 Settlers Freaks (sf-team at siedler25.org)
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "helpers/random.h"
+#include <random>
+
+namespace AI {
+
+std::minstd_rand& getRandomGenerator();
+
+template<typename T>
+T randomValue(T min = std::numeric_limits<T>::min(), T max = std::numeric_limits<T>::max())
+{
+    return helpers::randomValue(getRandomGenerator(), min, max);
+}
+
+} // namespace AI