Setup NPC director

Source/NakedDesire/NPC/NPCDirectorSubsystem.cpp

@@ -0,0 +1,232 @@
+// © 2025 Naked People Team. All Rights Reserved.
+
+
+#include "NPCDirectorSubsystem.h"
+
+#include "NPC.h"
+#include "NPCDirectorConfig.h"
+#include "NavigationSystem.h"
+#include "Engine/World.h"
+#include "GameFramework/Pawn.h"
+#include "Kismet/GameplayStatics.h"
+#include "NakedDesire/Global/NakedDesireGameInstance.h"
+
+void UNPCDirectorSubsystem::OnWorldBeginPlay(UWorld& InWorld)
+{
+	Super::OnWorldBeginPlay(InWorld);
+
+	if (!InWorld.IsGameWorld())
+		return;
+
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!Config || Config->SpawnTable.Num() == 0)
+		return;
+
+	if (UTimeOfDaySubsystem* Time = InWorld.GetSubsystem<UTimeOfDaySubsystem>())
+	{
+		Time->OnPhaseChanged.AddUniqueDynamic(this, &UNPCDirectorSubsystem::HandlePhaseChanged);
+		CachedPhase = Time->GetPhase();
+	}
+
+	PrewarmPool();
+
+	const float Interval = FMath::Max(Config->UpdateInterval, 0.05f);
+	InWorld.GetTimerManager().SetTimer(
+		UpdateTimerHandle, this, &UNPCDirectorSubsystem::UpdatePopulation, Interval, true);
+
+	UpdatePopulation();
+}
+
+void UNPCDirectorSubsystem::Deinitialize()
+{
+	if (const UWorld* World = GetWorld())
+	{
+		World->GetTimerManager().ClearTimer(UpdateTimerHandle);
+		if (UTimeOfDaySubsystem* Time = World->GetSubsystem<UTimeOfDaySubsystem>())
+			Time->OnPhaseChanged.RemoveDynamic(this, &UNPCDirectorSubsystem::HandlePhaseChanged);
+	}
+
+	Super::Deinitialize();
+}
+
+void UNPCDirectorSubsystem::HandlePhaseChanged(EDayPhase NewPhase)
+{
+	// The timer applies the new target on its next reconcile; just cache it.
+	CachedPhase = NewPhase;
+}
+
+void UNPCDirectorSubsystem::PrewarmPool()
+{
+	UWorld* World = GetWorld();
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!World || !Config)
+		return;
+
+	FActorSpawnParameters Params;
+	Params.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AlwaysSpawn;
+
+	for (int32 i = 0; i < Config->MaxNPCs; ++i)
+	{
+		const TSubclassOf<ANPC> NPCClass = PickWeightedClass();
+		if (!NPCClass)
+			continue;
+
+		ANPC* NPC = World->SpawnActor<ANPC>(NPCClass, FVector::ZeroVector, FRotator::ZeroRotator, Params);
+		if (!NPC)
+			continue;
+
+		NPC->DeactivateToPool();
+		Pool.Add(NPC);
+	}
+}
+
+void UNPCDirectorSubsystem::UpdatePopulation()
+{
+	const APawn* Player = GetPlayerPawn();
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!Player || !Config)
+		return;
+
+	const FVector PlayerLocation = Player->GetActorLocation();
+	const float DespawnRadiusSq = FMath::Square(Config->DespawnRadius);
+
+	// 1. Recycle anything that wandered (or was left) beyond the despawn radius.
+	for (int32 i = Active.Num() - 1; i >= 0; --i)
+	{
+		ANPC* NPC = Active[i];
+		if (!NPC || FVector::DistSquared(NPC->GetActorLocation(), PlayerLocation) > DespawnRadiusSq)
+			ReturnToPool(NPC);
+	}
+
+	const int32 Target = CurrentTargetCount();
+
+	// 2. Over target (e.g. day -> night drop): recycle the farthest live NPCs down to target.
+	while (Active.Num() > Target)
+	{
+		int32 FarthestIdx = INDEX_NONE;
+		float FarthestDistSq = -1.0f;
+		for (int32 i = 0; i < Active.Num(); ++i)
+		{
+			const float DistSq = FVector::DistSquared(Active[i]->GetActorLocation(), PlayerLocation);
+			if (DistSq > FarthestDistSq)
+			{
+				FarthestDistSq = DistSq;
+				FarthestIdx = i;
+			}
+		}
+		if (FarthestIdx == INDEX_NONE)
+			break;
+		ReturnToPool(Active[FarthestIdx]);
+	}
+
+	// 3. Under target: activate pooled NPCs at NavMesh points in the spawn ring.
+	while (Active.Num() < Target && Pool.Num() > 0)
+	{
+		FVector SpawnLocation;
+		if (!FindSpawnPoint(PlayerLocation, SpawnLocation))
+			break; // no reachable point this tick; try again next reconcile
+
+		ANPC* NPC = TakeFromPool();
+		if (!NPC)
+			break;
+
+		// Face away from the player so a newly activated NPC reads as walking into the scene.
+		const FRotator Facing = (SpawnLocation - PlayerLocation).GetSafeNormal2D().Rotation();
+		NPC->ActivateFromPool(SpawnLocation, Facing);
+		Active.Add(NPC);
+	}
+}
+
+int32 UNPCDirectorSubsystem::CurrentTargetCount() const
+{
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!Config)
+		return 0;
+
+	const int32 PhaseTarget = (CachedPhase == EDayPhase::Day) ? Config->TargetCountDay : Config->TargetCountNight;
+	// Can never exceed what the pool can hold.
+	return FMath::Clamp(PhaseTarget, 0, Config->MaxNPCs);
+}
+
+ANPC* UNPCDirectorSubsystem::TakeFromPool()
+{
+	while (Pool.Num() > 0)
+	{
+		ANPC* NPC = Pool.Pop(EAllowShrinking::No);
+		if (NPC)
+			return NPC;
+	}
+	return nullptr;
+}
+
+void UNPCDirectorSubsystem::ReturnToPool(ANPC* NPC)
+{
+	Active.RemoveSwap(NPC);
+	if (NPC)
+	{
+		NPC->DeactivateToPool();
+		Pool.Add(NPC);
+	}
+}
+
+TSubclassOf<ANPC> UNPCDirectorSubsystem::PickWeightedClass() const
+{
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!Config)
+		return nullptr;
+
+	float TotalWeight = 0.0f;
+	for (const FNPCSpawnEntry& Entry : Config->SpawnTable)
+	{
+		if (Entry.NPCClass && Entry.Weight > 0.0f)
+			TotalWeight += Entry.Weight;
+	}
+	if (TotalWeight <= 0.0f)
+		return nullptr;
+
+	float Roll = FMath::FRandRange(0.0f, TotalWeight);
+	for (const FNPCSpawnEntry& Entry : Config->SpawnTable)
+	{
+		if (!Entry.NPCClass || Entry.Weight <= 0.0f)
+			continue;
+		Roll -= Entry.Weight;
+		if (Roll <= 0.0f)
+			return Entry.NPCClass;
+	}
+	return nullptr;
+}
+
+bool UNPCDirectorSubsystem::FindSpawnPoint(const FVector& Around, FVector& OutLocation) const
+{
+	UNavigationSystemV1* NavSys = UNavigationSystemV1::GetCurrent(GetWorld());
+	const UNPCDirectorConfig* Config = GetConfig();
+	if (!NavSys || !Config)
+		return false;
+
+	const float MinRadiusSq = FMath::Square(Config->SpawnRadiusMin);
+
+	// Rejection-sample a reachable point in the outer radius until one lands outside the inner radius.
+	for (int32 Attempt = 0; Attempt < 8; ++Attempt)
+	{
+		FNavLocation NavLocation;
+		if (NavSys->GetRandomReachablePointInRadius(Around, Config->SpawnRadiusMax, NavLocation) &&
+			FVector::DistSquared(NavLocation.Location, Around) >= MinRadiusSq)
+		{
+			OutLocation = NavLocation.Location;
+			return true;
+		}
+	}
+	return false;
+}
+
+APawn* UNPCDirectorSubsystem::GetPlayerPawn() const
+{
+	return UGameplayStatics::GetPlayerPawn(GetWorld(), 0);
+}
+
+UNPCDirectorConfig* UNPCDirectorSubsystem::GetConfig() const
+{
+	const UNakedDesireGameInstance* GameInstance =
+		Cast<UNakedDesireGameInstance>(GetWorld() ? GetWorld()->GetGameInstance() : nullptr);
+	return GameInstance ? GameInstance->NPCDirector : nullptr;
+}