[server] fix sparse world generator not being seed-deterministic #5

Author: FreddyMSchubert

Makefile

@@ -13,7 +13,7 @@ SERVER_EXECUTABLE := server
 # Configs
 CONFIG_FOLDER := my-core-bot/configs
 CONFIG_SERVER_FILE := $(CONFIG_FOLDER)/server-config.json
-CONFIG_GAME_FILE := $(CONFIG_FOLDER)/hard-config.json
+CONFIG_GAME_FILE := $(CONFIG_FOLDER)/soft-config.json
 
 # Git info
 CURRENT_BRANCH := $(shell git rev-parse --abbrev-ref HEAD)

my-core-bot

@@ -44,14 +44,6 @@ struct Position
 	{
 		return std::abs(x - other.x) + std::abs(y - other.y);
 	}
-
-	static Position random(int maxSizeSquare)
-	{
-		static std::default_random_engine eng = std::default_random_engine(time(nullptr));
-		std::uniform_int_distribution<int> posX(0, maxSizeSquare - 1);
-		std::uniform_int_distribution<int> posY(0, maxSizeSquare - 1);
-		return Position(posX(eng), posY(eng));
-	}
 };
 
 #endif // COMMON_H

server/inc/Common.h

@@ -20,7 +20,7 @@ class SparseWorldGenerator : public WorldGenerator
 		void generateWorld(unsigned int seed);
 
 	private:
-		std::mt19937_64 eng_ = std::mt19937_64(std::chrono::system_clock::now().time_since_epoch().count());
+		std::mt19937_64 eng_{};
 };
 
 #endif // DISTANCED_RESOURCE_WORLD_GENERATOR_H

server/inc/config/worldgen/SparseWorldGenerator.h

@@ -22,7 +22,7 @@ static bool positionHasNeighbours(const Position& pos, int N)
 
 void SparseWorldGenerator::generateWorld(unsigned int seed)
 {
-	eng_ = std::mt19937_64(seed);
+	eng_.seed(seed);
 
 	unsigned int gridSize = Config::game().gridSize;
 	int depositCount = Config::game().worldGeneratorConfig.value("depositCount", 20);
@@ -43,7 +43,8 @@ void SparseWorldGenerator::generateWorld(unsigned int seed)
 
 	const int N = static_cast<int>(gridSize);
 	auto tryPlace = [&](ObjectType t) -> bool {
-		Position p = Position::random(gridSize);
+		static std::uniform_int_distribution<int> dist(0, static_cast<int>(gridSize) - 1);
+		Position p{dist(eng_), dist(eng_)};
 		if (p.x < 0 || p.x >= N || p.y < 0 || p.y >= N) return false;
 		if (Board::instance().getObjectAtPos(p)) return false;
 		if (positionHasNeighbours(p, N)) return false;