Set up basic deterministic lockstep

src/game_server/InternalGameServer.cpp

@@ -9,7 +9,7 @@ namespace FRG {
 
 namespace {
 constexpr const char* kBattleZoneCampaignId = "battle_zone";
-constexpr const char* kBattleZoneTestBotId = "battle_zone_test_bot";
+constexpr const char* kBattleZonePlayer2Id = "player2";
 constexpr std::int64_t kBattleZoneTestBotIntervalMs = 5000;
 
 void configurePlayerAnimations(
@@ -44,11 +44,11 @@ void InternalGameServer::ensureBattleZoneTestBot()
 {
 	if (state_.campaignId != kBattleZoneCampaignId) return;
 	if (!battleZoneTestBotEnabled_) {
-		state_.players.erase(kBattleZoneTestBotId);
+		state_.players.erase(kBattleZonePlayer2Id);
 		return;
 	}
 
-	auto& bot = state_.players[kBattleZoneTestBotId];
+	auto& bot = state_.players[kBattleZonePlayer2Id];
 	if (!bot) bot = std::make_shared<CharacterState>();
 	bot->configureAsPlayer();
 	configurePlayerAnimations(*bot, resourceZipFile_);
@@ -60,7 +60,7 @@ void InternalGameServer::updateBattleZoneTestBot(std::int64_t deltaMs)
 	if (!battleZoneTestBotEnabled_ ||
 		state_.campaignId != kBattleZoneCampaignId ||
 		state_.currentLocationName.empty() ||
-		state_.players.find(kBattleZoneTestBotId) == state_.players.end()) {
+		state_.players.find(kBattleZonePlayer2Id) == state_.players.end()) {
 		return;
 	}
 
@@ -72,7 +72,7 @@ void InternalGameServer::updateBattleZoneTestBot(std::int64_t deltaMs)
 	static std::uniform_real_distribution<float> coordinate(-10.0f, 10.0f);
 	submit(SetCharacterDestinationCommand{
 		state_.currentLocationName,
-		kBattleZoneTestBotId,
+		kBattleZonePlayer2Id,
 		Eigen::Vector3f(coordinate(randomEngine), 0.f, coordinate(randomEngine)),
 		std::string()});
 }
@@ -92,6 +92,7 @@ void InternalGameServer::startCampaign(
 	bool createLocalPlayer, bool enableTestBot)
 {
 	resourceZipFile_ = zipFile;
+	networkPlayerSlots_ = campaign.networkPlayerSlots;
 	battleZoneTestBotEnabled_ = enableTestBot;
 	state_.campaignId = campaign.id;
 	state_.currentLocationName.clear();
@@ -125,6 +126,7 @@ void InternalGameServer::clearCampaign()
 	state_.currentLocationName.clear();
 	state_.players.clear();
 	state_.locations.clear();
+	networkPlayerSlots_.clear();
 	battleZoneTestBotElapsedMs_ = 0;
 	publishMutation();
 }
@@ -487,6 +489,19 @@ void InternalGameServer::update(std::int64_t deltaMs)
 	pendingSimulationLocationId_ = state_.currentLocationName;
 	pendingSimulationEvents_ =
 		stored->second.update(deltaMs, state_.players, interactiveObjectsLocked);
+	// Navigation recovery is a simulation consequence, not presentation input.
+	// Applying it here makes every lockstep replica produce the same follow-up.
+	for (const CharacterSimulationEvent& event :
+			pendingSimulationEvents_.characters) {
+		if (!event.events.navigationRequested) continue;
+		CharacterState* character = state_.findCharacter(
+			state_.currentLocationName, event.characterId);
+		if (character && stored->second.location) {
+			character->setTarget(
+				event.events.navigationTarget, {},
+				*stored->second.location, event.characterId);
+		}
+	}
 	publishMutation();
 }
 
@@ -499,6 +514,12 @@ void InternalGameServer::load(const nlohmann::json& in)
 {
 	pendingEvents_.clear();
 	state_.load(in);
+	for (const std::string& playerId : networkPlayerSlots_) {
+		auto player = state_.players.find(playerId);
+		if (player == state_.players.end() || !player->second) continue;
+		player->second->configureAsPlayer();
+		configurePlayerAnimations(*player->second, resourceZipFile_);
+	}
 	battleZoneTestBotElapsedMs_ = 0;
 	ensureBattleZoneTestBot();
 	publishMutation();