SublevelComponent.cpp

// Copyright Redpoint Games Pty Ltd 2017 All Rights Reserved. Some portions of this code are from Rama's Victory BP Library, which is licensed separately.

#include "SublevelComponent.h"
#include "Misc/PackageName.h"
#include "Engine/World.h"
#include "UnrealNetwork.h"

USublevelComponent::USublevelComponent()
{
	PrimaryComponentTick.bCanEverTick = true;
}

void USublevelComponent::EndPlay(const EEndPlayReason::Type type)
{
	if (!CurrentLevelStreamInfo.PackageNameToLoad.IsNone())
	{
		RemoveFromStreamingLevels(CurrentLevelStreamInfo);
		CurrentLevelStreamInfo.PackageNameToLoad = TEXT("");
	}

	Super::EndPlay(type);
}

void USublevelComponent::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{
	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);

	UWorld* const World = GetWorld();

	if (World->IsServer())
	{
		if (!LastSetLevelPath.Equals(LevelPath))
		{
			FString LongPackageName;
			bool bFoundPackage = FPackageName::SearchForPackageOnDisk(LevelPath, &LongPackageName);
			if (bFoundPackage)
			{
				TargetLevelStreamInfo.PackageNameToLoad = FName(*LongPackageName);
				LastSetLevelPath = LevelPath;
			}
			else
			{
				TargetLevelStreamInfo.PackageNameToLoad = NAME_None;
			}
		}

		TargetLevelStreamInfo.Location = GetComponentToWorld().GetLocation();
		TargetLevelStreamInfo.Rotation = GetComponentToWorld().GetRotation().Rotator();
		TargetLevelStreamInfo.bShouldBeLoaded = LevelActive;
		TargetLevelStreamInfo.bShouldBeVisible = LevelActive;
		TargetLevelStreamInfo.bShouldBlockOnLoad = false;
		TargetLevelStreamInfo.LODIndex = 1;

		if (TargetLevelStreamInfo.PackageNameToLoad != CurrentLevelStreamInfo.PackageNameToLoad ||
			TargetLevelStreamInfo.Location != CurrentLevelStreamInfo.Location ||
			TargetLevelStreamInfo.Rotation != CurrentLevelStreamInfo.Rotation ||
			TargetLevelStreamInfo.bShouldBeLoaded != CurrentLevelStreamInfo.bShouldBeLoaded ||
			TargetLevelStreamInfo.bShouldBeVisible != CurrentLevelStreamInfo.bShouldBeVisible ||
			TargetLevelStreamInfo.bShouldBlockOnLoad != CurrentLevelStreamInfo.bShouldBlockOnLoad ||
			TargetLevelStreamInfo.LODIndex != CurrentLevelStreamInfo.LODIndex)
		{
			// Things are out of sync on the server!
			if (!CurrentLevelStreamInfo.PackageNameToLoad.IsNone())
			{
				RemoveFromStreamingLevels(CurrentLevelStreamInfo);
				CurrentLevelStreamInfo.PackageNameToLoad = NAME_None;
			}

			CurrentLevelStreamInfo = TargetLevelStreamInfo;

			// Generate a new unique package name.
			const FString ShortPackageName = FPackageName::GetShortName(CurrentLevelStreamInfo.PackageNameToLoad.ToString());
			const FString PackagePath = FPackageName::GetLongPackagePath(CurrentLevelStreamInfo.PackageNameToLoad.ToString());
			FString UniqueLevelPackageName = PackagePath + TEXT("/") + World->StreamingLevelsPrefix + ShortPackageName;
			UniqueLevelPackageName += TEXT("_LevelInstance_") + FString::FromInt(this->GetUniqueID());
			CurrentLevelStreamInfo.PackageName = FName(*UniqueLevelPackageName);
			TargetLevelStreamInfo.PackageName = CurrentLevelStreamInfo.PackageName; // Replicate to clients.

			if (!CurrentLevelStreamInfo.PackageNameToLoad.IsNone())
			{
				AddToStreamingLevels(CurrentLevelStreamInfo);
			}
		}
	}
	else
	{
		if (TargetLevelStreamInfo.PackageName != CurrentLevelStreamInfo.PackageName ||
			TargetLevelStreamInfo.PackageNameToLoad != CurrentLevelStreamInfo.PackageNameToLoad ||
			TargetLevelStreamInfo.Location != CurrentLevelStreamInfo.Location ||
			TargetLevelStreamInfo.Rotation != CurrentLevelStreamInfo.Rotation ||
			TargetLevelStreamInfo.bShouldBeLoaded != CurrentLevelStreamInfo.bShouldBeLoaded ||
			TargetLevelStreamInfo.bShouldBeVisible != CurrentLevelStreamInfo.bShouldBeVisible ||
			TargetLevelStreamInfo.bShouldBlockOnLoad != CurrentLevelStreamInfo.bShouldBlockOnLoad ||
			TargetLevelStreamInfo.LODIndex != CurrentLevelStreamInfo.LODIndex)
		{
			// Things are out of sync on the client!
			if (!CurrentLevelStreamInfo.PackageNameToLoad.IsNone() &&
				!CurrentLevelStreamInfo.PackageName.IsNone())
			{
				RemoveFromStreamingLevels(CurrentLevelStreamInfo);
				CurrentLevelStreamInfo.PackageNameToLoad = NAME_None;
			}

			CurrentLevelStreamInfo = TargetLevelStreamInfo;

			if (!CurrentLevelStreamInfo.PackageNameToLoad.IsNone() &&
				!CurrentLevelStreamInfo.PackageName.IsNone())
			{
				AddToStreamingLevels(CurrentLevelStreamInfo);
			}
		}
	}
}

void USublevelComponent::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
{
	Super::GetLifetimeReplicatedProps(OutLifetimeProps);

	DOREPLIFETIME(USublevelComponent, LevelPath);
	DOREPLIFETIME(USublevelComponent, LevelActive);
	DOREPLIFETIME(USublevelComponent, TargetLevelStreamInfo);
}

void USublevelComponent::AddToStreamingLevels(const FLevelStreamInstanceInfo& LevelInstanceInfo)
{
	bool bResult = true;

	UWorld* const World = GetWorld();

	if (World != nullptr)
	{
		bool bAlreadyExists = false;

		for (auto StreamingLevel : World->StreamingLevels)
		{
			if (StreamingLevel->GetWorldAssetPackageFName() == LevelInstanceInfo.PackageName)
			{
				bAlreadyExists = true;
				break;
			}
		}

		if (!bAlreadyExists)
		{
			FName PackageName = LevelInstanceInfo.PackageName;

			// For PIE Networking: remap the packagename to our local PIE packagename
			FString PackageNameStr = PackageName.ToString();
			if (GEngine->NetworkRemapPath(World->GetNetDriver(), PackageNameStr, true))
			{
				PackageName = FName(*PackageNameStr);
			}

			World->DelayGarbageCollection();

			// Setup streaming level object that will load specified map
			ULevelStreamingKismet* StreamingLevel = NewObject<ULevelStreamingKismet>(World, ULevelStreamingKismet::StaticClass(), NAME_None, RF_Transient, nullptr);
			StreamingLevel->SetWorldAssetByPackageName(PackageName);
			StreamingLevel->LevelColor = FColor::MakeRandomColor();
			StreamingLevel->bShouldBeLoaded = LevelInstanceInfo.bShouldBeLoaded;
			StreamingLevel->bShouldBeVisible = LevelInstanceInfo.bShouldBeVisible;
			StreamingLevel->bShouldBlockOnLoad = LevelInstanceInfo.bShouldBlockOnLoad;
			StreamingLevel->bInitiallyLoaded = true;
			StreamingLevel->bInitiallyVisible = true;

			// Transform
			StreamingLevel->LevelTransform = FTransform(LevelInstanceInfo.Rotation, LevelInstanceInfo.Location);

			// Map to Load
			StreamingLevel->PackageNameToLoad = LevelInstanceInfo.PackageNameToLoad;

			// Add the new level to world.
			World->StreamingLevels.Add(StreamingLevel);

			World->FlushLevelStreaming(EFlushLevelStreamingType::Full);
		}
	}
}

void USublevelComponent::RemoveFromStreamingLevels(const FLevelStreamInstanceInfo& LevelInstanceInfo)
{
	UWorld* const World = GetWorld();

	// Check if the world exists and we have a level to unload
	if (World != nullptr && !LevelInstanceInfo.PackageName.IsNone())
	{

#if WITH_EDITOR
		// If we are using the editor we will use this lambda to remove the play in editor string
		auto GetCorrectPackageName = [&](FName PackageName) {
			FString PackageNameStr = PackageName.ToString();
			if (GEngine->NetworkRemapPath(World->GetNetDriver(), PackageNameStr, true))
			{
				PackageName = FName(*PackageNameStr);
			}

			return PackageName;
		};
#endif

		// Get the package name that we want to check
		FName PackageNameToCheck = LevelInstanceInfo.PackageName;

#if WITH_EDITOR
		// Remove the play in editor string and client id to be able to use it with replication
		PackageNameToCheck = GetCorrectPackageName(PackageNameToCheck);
#endif

		// Find the level to unload
		for (auto StreamingLevel : World->StreamingLevels)
		{

			FName LoadedPackageName = StreamingLevel->GetWorldAssetPackageFName();

#if WITH_EDITOR
			// Remove the play in editor string and client id to be able to use it with replication
			LoadedPackageName = GetCorrectPackageName(LoadedPackageName);
#endif

			// If we find the level unload it and break
			if (PackageNameToCheck == LoadedPackageName)
			{
				// This unload the level
				StreamingLevel->bShouldBeLoaded = false;
				StreamingLevel->bShouldBeVisible = false;
				// This removes the level from the streaming level list
				StreamingLevel->bIsRequestingUnloadAndRemoval = true;
				// Force a refresh of the world
				World->FlushLevelStreaming(EFlushLevelStreamingType::Full);
				break;
			}
		}
	}
}

SublevelComponent.h

// Copyright Redpoint Games Pty Ltd 2017 All Rights Reserved. Some portions of this code are from Rama's Victory BP Library, which is licensed separately.

#pragma once

#include "CoreMinimal.h"
#include "Components/SceneComponent.h"
#include "Engine/LevelStreamingKismet.h"
#include "Engine.h"
#include "SublevelComponent.generated.h"

USTRUCT(BlueprintType)
struct FLevelStreamInstanceInfo
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY()
	FName PackageName;

	UPROPERTY()
	FName PackageNameToLoad;

	UPROPERTY()
	FVector Location;

	UPROPERTY()
	FRotator Rotation;

	UPROPERTY()
	uint8 bShouldBeLoaded : 1;

	UPROPERTY()
	uint8 bShouldBeVisible : 1;

	UPROPERTY()
	uint8 bShouldBlockOnLoad : 1;

	UPROPERTY()
	int32 LODIndex;

	FLevelStreamInstanceInfo() {}

	FLevelStreamInstanceInfo(ULevelStreamingKismet* LevelInstance);

	FString ToString() const
	{
		return FString::Printf(TEXT("PackageName: %s\nPackageNameToLoad:%s\nLocation:%s\nRotation:%s\nbShouldBeLoaded:%s\nbShouldBeVisible:%s\nbShouldBlockOnLoad:%s\nLODIndex:%i")
			, *PackageName.ToString()
			, *PackageNameToLoad.ToString()
			, *Location.ToString()
			, *Rotation.ToString()
			, (bShouldBeLoaded) ? TEXT("True") : TEXT("False")
			, (bShouldBeVisible) ? TEXT("True") : TEXT("False")
			, (bShouldBlockOnLoad) ? TEXT("True") : TEXT("False")
			, LODIndex);
	}
};

UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class MINUTEOFMAYHEM_API USublevelComponent : public USceneComponent
{
	GENERATED_BODY()

public:	
	// Sets default values for this component's properties
	USublevelComponent();

	/** The path to the level asset to manage as a sublevel instance */
	UPROPERTY(Replicated, BlueprintReadWrite, EditAnywhere, Category = "Level")
	FString LevelPath;

	UPROPERTY(Replicated, BlueprintReadWrite, EditAnywhere, Category = "Level")
	bool LevelActive;

protected:
	virtual void EndPlay(const EEndPlayReason::Type type) override;

public:	
	virtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;

private:
	UPROPERTY(Replicated)
	FLevelStreamInstanceInfo TargetLevelStreamInfo;

	UPROPERTY()
	FLevelStreamInstanceInfo CurrentLevelStreamInfo;

	FString LastSetLevelPath;

	void AddToStreamingLevels(const FLevelStreamInstanceInfo& LevelInstanceInfo);
	void RemoveFromStreamingLevels(const FLevelStreamInstanceInfo& LevelInstanceInfo);
	
};