feat(enhancement): Add "on encounter" trigger for NPCs

source/Engine.cpp

@@ -609,6 +609,7 @@ void Engine::Step(bool isActive)
 		player.SetPlanet(flagship->GetPlanet());
 
 	const System *currentSystem = player.GetSystem();
+
 	// Update this here, for thread safety.
 	if(player.HasTravelPlan() && currentSystem == player.TravelPlan().back())
 		player.PopTravel();
@@ -1394,6 +1395,11 @@ void Engine::EnterSystem()
 		Messages::Add(GameData::HelpMessage("basics 1"), Messages::Importance::High);
 		Messages::Add(GameData::HelpMessage("basics 2"), Messages::Importance::High);
 	}
+
+	if(flagship->Cloaking() < 1.)
+		for(const shared_ptr<Ship> &ship : ships)
+			if(ship->GetSystem() == system && ship->Cloaking() < 1.)
+				eventQueue.emplace_back(player.FlagshipPtr(), ship, ShipEvent::ENCOUNTER);
 }
 
 
@@ -1461,10 +1467,22 @@ void Engine::CalculateStep()
 
 	// Keep track of the flagship to see if it jumps or enters a wormhole this turn.
 	const Ship *flagship = player.Flagship();
+	bool flagshipWasCloaked = (flagship && flagship->Cloaking() == 1);
 	bool wasHyperspacing = (flagship && flagship->IsEnteringHyperspace());
-	// Move all the ships.
+	// First, move the player's flagship.
+	MoveShip(player.FlagshipPtr());
+	// Then, move all the rest of the ships.
 	for(const shared_ptr<Ship> &it : ships)
+	{
+		if(it == player.FlagshipPtr())
+			continue;
+		bool wasCloaked = (it->Cloaking() == 1.);
 		MoveShip(it);
+		// If we decloaked, *or* the player decloaked, and we're in the same system as the player, they encounter us.
+		if(((wasCloaked && it->Cloaking() < 1.) || (flagshipWasCloaked && flagship->Cloaking() < 1.))
+			&& flagship->GetSystem() == it->GetSystem() && flagship->Cloaking() < 1.)
+				eventQueue.emplace_back(player.FlagshipPtr(), it, ShipEvent::ENCOUNTER);
+	}
 	// If the flagship just began jumping, play the appropriate sound.
 	if(!wasHyperspacing && flagship && flagship->IsEnteringHyperspace())
 	{
@@ -1729,6 +1747,9 @@ void Engine::MoveShip(const shared_ptr<Ship> &ship)
 			else
 				for(const auto &sound : jumpSounds)
 					Audio::Play(sound.first, position);
+
+			if(flagship->Cloaking() < 1. && ship->Cloaking() < 1.)
+				eventQueue.emplace_back(player.FlagshipPtr(), ship, ShipEvent::ENCOUNTER);
 		}
 	}
 

source/NPC.cpp

@@ -59,6 +59,8 @@ namespace {
 				return "on destroy";
 			case NPC::Trigger::KILL:
 				return "on kill";
+			case NPC::Trigger::ENCOUNTER:
+				return "on encounter";
 			default:
 				return "unknown trigger";
 		}
@@ -197,7 +199,8 @@ void NPC::Load(const DataNode &node)
 				{"board", Trigger::BOARD},
 				{"capture", Trigger::CAPTURE},
 				{"destroy", Trigger::DESTROY},
-				{"kill", Trigger::KILL}
+				{"kill", Trigger::KILL},
+				{"encounter", Trigger::ENCOUNTER},
 			};
 			auto it = trigger.find(child.Token(1));
 			if(it != trigger.end())
@@ -747,6 +750,7 @@ void NPC::DoActions(const ShipEvent &event, bool newEvent, PlayerInfo &player, U
 		{ShipEvent::BOARD, {Trigger::BOARD}},
 		{ShipEvent::CAPTURE, {Trigger::CAPTURE, Trigger::KILL}},
 		{ShipEvent::DESTROY, {Trigger::DESTROY, Trigger::KILL}},
+		{ShipEvent::ENCOUNTER, {Trigger::ENCOUNTER}},
 	};
 
 	int type = event.Type();
@@ -778,7 +782,8 @@ void NPC::DoActions(const ShipEvent &event, bool newEvent, PlayerInfo &player, U
 			{Trigger::BOARD, ShipEvent::BOARD},
 			{Trigger::CAPTURE, ShipEvent::CAPTURE},
 			{Trigger::DESTROY, ShipEvent::DESTROY},
-			{Trigger::KILL, ShipEvent::CAPTURE | ShipEvent::DESTROY}
+			{Trigger::KILL, ShipEvent::CAPTURE | ShipEvent::DESTROY},
+			{Trigger::ENCOUNTER, ShipEvent::ENCOUNTER},
 		};
 
 		// Some Triggers cannot be met if any of the ships in this NPC have certain events.
@@ -792,10 +797,10 @@ void NPC::DoActions(const ShipEvent &event, bool newEvent, PlayerInfo &player, U
 		const auto excludedIt = triggerExclusions.find(trigger);
 		const int excludedEvents = excludedIt == triggerExclusions.end() ? 0 : excludedIt->second;
 
-		// The PROVOKE Trigger only requires a single ship to receive the
+		// The PROVOKE and ENCOUNTER Triggers only requires a single ship to receive the
 		// event in order to run. All other Triggers require that all ships
 		// be affected.
-		if(trigger == Trigger::PROVOKE || all_of(ships.begin(), ships.end(),
+		if(trigger == Trigger::ENCOUNTER || trigger == Trigger::PROVOKE || all_of(ships.begin(), ships.end(),
 				[&](const shared_ptr<Ship> &ship) -> bool
 				{
 					auto it = shipEvents.find(ship.get());

source/NPC.h

@@ -61,7 +61,8 @@ class NPC {
 		CAPTURE,
 		DESTROY,
 		// Can be triggered by either the CAPTURE or DESTROY events.
-		KILL
+		KILL,
+		ENCOUNTER,
 	};
 
 

source/ShipEvent.h

@@ -66,7 +66,9 @@ class ShipEvent {
 		// you had with the given government, first.
 		ATROCITY = (1 << 8),
 		// This ship just jumped into a different system.
-		JUMP = (1 << 9)
+		JUMP = (1 << 9),
+		// This ship just met another ship for the first time
+		ENCOUNTER = (1 << 10),
 	};