Merge pull request #1739 from wichern/use-random-in-aijh

Make AIJH Actions Reproducible by using the user selectable Random Seed

Author: Flamefire

extras/ai-battle/main.cpp

@@ -7,6 +7,7 @@
 #include "QuickStartGame.h"
 #include "RTTR_Version.h"
 #include "RttrConfig.h"
+#include "ai/random.h"
 #include "files.h"
 #include "random/Random.h"
 #include "s25util/System.h"
@@ -30,6 +31,7 @@ int main(int argc, char** argv)
     boost::optional<std::string> replay_path;
     boost::optional<std::string> savegame_path;
     unsigned random_init = static_cast<unsigned>(std::chrono::high_resolution_clock::now().time_since_epoch().count());
+    unsigned random_ai_init = random_init;
 
     po::options_description desc("Allowed options");
     // clang-format off
@@ -41,6 +43,7 @@ int main(int argc, char** argv)
         ("replay", po::value(&replay_path),"Filename to write replay to (optional)")
         ("save", po::value(&savegame_path),"Filename to write savegame to (optional)")
         ("random_init", po::value(&random_init),"Seed value for the random number generator (optional)")
+        ("random_ai_init", po::value(&random_ai_init),"Seed value for the AI random number generator (optional)")
         ("maxGF", po::value<unsigned>()->default_value(std::numeric_limits<unsigned>::max()),"Maximum number of game frames to run (optional)")
         ("version", "Show version information and exit")
         ;
@@ -85,10 +88,12 @@ int main(int argc, char** argv)
             bnw::cout << argv[i] << " ";
         bnw::cout << std::endl;
         bnw::cout << "random_init: " << random_init << std::endl;
+        bnw::cout << "random_ai_init: " << random_ai_init << std::endl;
         bnw::cout << std::endl;
 
         RTTRCONFIG.Init();
         RANDOM.Init(random_init);
+        AI::getRandomGenerator().seed(random_ai_init);
 
         const bfs::path mapPath = RTTRCONFIG.ExpandPath(options["map"].as<std::string>());
         const std::vector<AI::Info> ais = ParseAIOptions(options["ai"].as<std::vector<std::string>>());

libs/common/include/helpers/random.h

@@ -24,6 +24,17 @@ T randomValue(RandomT& rng, T min = std::numeric_limits<T>::min(), T max = std::
     return static_cast<T>(distr(rng));
 }
 
+/// Return a true in `chance` out of `total` cases:
+///   randomChance()       ... return true|false with 50% chance each
+///   randomChance(15)     ... return true in 1/15 of the cases
+///   randomChance(20, 5)  ... return true in 5 out of 20 cases, i.e. a probability of 25%. Sames as randomChance(4, 1)
+template<typename RandomT>
+bool randomChance(RandomT& rng, unsigned total = 2u, unsigned chance = 1u)
+{
+    RTTR_Assert(total > 0u);
+    return (chance >= total) || randomValue(rng, 1u, total) <= chance;
+}
+
 /// Return a random enumerator from the given enum
 template<typename T, typename RandomT>
 T randomEnum(RandomT& rng)

libs/s25main/ai/aijh/AIConstruction.cpp

@@ -1,4 +1,4 @@
-// Copyright (C) 2005 - 2024 Settlers Freaks (sf-team at siedler25.org)
+// Copyright (C) 2005 - 2026 Settlers Freaks (sf-team at siedler25.org)
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -10,6 +10,7 @@
 #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"
@@ -465,20 +466,21 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
     const BuildingType biggestBld = GetBiggestAllowedMilBuilding().value();
 
     const Inventory& inventory = aii.GetInventory();
-    if(((rand() % 3) == 0 || inventory.people[Job::Private] < 15)
+    if((inventory.people[Job::Private] < 15 || AI::randomChance(3))
        && (inventory.goods[GoodType::Stones] > 6 || bldPlanner.GetNumBuildings(BuildingType::Quarry) > 0))
         bld = BuildingType::Guardhouse;
-    if(aijh.getAIInterface().isHarborPosClose(pt, 19) && rand() % 10 != 0 && aijh.ggs.isEnabled(AddonId::SEA_ATTACK))
+    if(aijh.getAIInterface().isHarborPosClose(pt, 19) && !AI::randomChance(10)
+       && aijh.ggs.isEnabled(AddonId::SEA_ATTACK))
     {
         if(aii.CanBuildBuildingtype(BuildingType::Watchtower))
             return BuildingType::Watchtower;
         return GetBiggestAllowedMilBuilding();
     }
     if(biggestBld == BuildingType::Watchtower || biggestBld == BuildingType::Fortress)
     {
-        if(aijh.UpdateUpgradeBuilding() < 0 && bldPlanner.GetNumBuildingSites(biggestBld) < 1
+        if(!aijh.UpdateUpgradeBuilding() && bldPlanner.GetNumBuildingSites(biggestBld) < 1
            && (inventory.goods[GoodType::Stones] > 20 || bldPlanner.GetNumBuildings(BuildingType::Quarry) > 0)
-           && rand() % 10 != 0)
+           && !AI::randomChance(10))
         {
             return biggestBld;
         }
@@ -488,23 +490,22 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
     sortedMilitaryBlds military = aii.gwb.LookForMilitaryBuildings(pt, 3);
     for(const nobBaseMilitary* milBld : military)
     {
-        unsigned distance = aii.gwb.CalcDistance(milBld->GetPos(), pt);
+        const unsigned distance = aii.gwb.CalcDistance(milBld->GetPos(), pt);
 
-        // Prüfen ob Feind in der Nähe
+        // Check for close enemy
         if(milBld->GetPlayer() != playerId && distance < 35)
         {
-            int randmil = rand();
-            bool buildCatapult = randmil % 8 == 0 && aii.CanBuildCatapult()
+            bool buildCatapult = AI::randomChance(8) && aii.CanBuildCatapult()
                                  && bldPlanner.GetNumAdditionalBuildingsWanted(BuildingType::Catapult) > 0;
-            // another catapult within "min" radius? ->dont build here!
-            const unsigned min = 16;
-            if(buildCatapult && aii.gwb.CalcDistance(pt, aii.GetStorehouses().front()->GetPos()) < min)
+            // another catapult within this radius? ->dont build here!
+            constexpr unsigned minCatapultDist = 16;
+            if(buildCatapult && aii.gwb.CalcDistance(pt, aii.GetStorehouses().front()->GetPos()) < minCatapultDist)
                 buildCatapult = false;
             if(buildCatapult)
             {
                 for(const nobUsual* catapult : aii.GetBuildings(BuildingType::Catapult))
                 {
-                    if(aii.gwb.CalcDistance(pt, catapult->GetPos()) < min)
+                    if(aii.gwb.CalcDistance(pt, catapult->GetPos()) < minCatapultDist)
                     {
                         buildCatapult = false;
                         break;
@@ -515,7 +516,8 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
             {
                 for(const noBuildingSite* bldSite : aii.GetBuildingSites())
                 {
-                    if(bldSite->GetBuildingType() == bld && aii.gwb.CalcDistance(pt, bldSite->GetPos()) < min)
+                    if(bldSite->GetBuildingType() == bld
+                       && aii.gwb.CalcDistance(pt, bldSite->GetPos()) < minCatapultDist)
                     {
                         buildCatapult = false;
                         break;
@@ -526,19 +528,21 @@ helpers::OptionalEnum<BuildingType> AIConstruction::ChooseMilitaryBuilding(const
                 bld = BuildingType::Catapult;
             else
             {
-                if(randmil % 2 == 0 && aii.CanBuildBuildingtype(BuildingType::Watchtower))
-                    bld = BuildingType::Watchtower;
-                else
-                    bld = biggestBld;
-            }
-            // slim chance for a guardhouse instead of tower or fortress so we can expand towards an enemy even if there
-            // are no big building spots in that direction
-            if(randmil % 10 == 0)
-            {
-                if(aii.CanBuildBuildingtype(BuildingType::Guardhouse))
-                    bld = BuildingType::Guardhouse;
-                else
-                    bld = GetSmallestAllowedMilBuilding();
+                // slim chance for a guardhouse instead of tower or fortress so we can expand towards an enemy even if
+                // there are no big building spots in that direction
+                if(AI::randomChance(10))
+                {
+                    if(aii.CanBuildBuildingtype(BuildingType::Guardhouse))
+                        bld = BuildingType::Guardhouse;
+                    else
+                        bld = GetSmallestAllowedMilBuilding();
+                } else
+                {
+                    if(aii.CanBuildBuildingtype(BuildingType::Watchtower) && AI::randomChance())
+                        bld = BuildingType::Watchtower;
+                    else
+                        bld = biggestBld;
+                }
             }
             break;
         }