Implement custom GameInstance initialization so that game knows wheth…

…er it is dedicated server by the time UGameInstance::Init is called
slonopotamus · Aug 21, 2024 · c5dfc5e · c5dfc5e
1 parent 98043de
commit c5dfc5e
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Showing 5 changed files with 87 additions and 8 deletions.
diff --git a/Source/UEST/Private/ScopedGame.cpp b/Source/UEST/Private/ScopedGame.cpp
@@ -6,6 +6,7 @@
 #include "Iris/ReplicationSystem/ObjectReplicationBridge.h"
 #include "Iris/ReplicationSystem/ReplicationSystem.h"
 #include "Net/OnlineEngineInterface.h"
+#include "UESTGameInstance.h"
 
 struct TGWorldGuard final : FNoncopyable
 {
@@ -58,7 +59,7 @@ static TUniquePtr<FCVarsGuard> CVarsGuard;
 
 FScopedGameInstance::FScopedGameInstance(TSubclassOf<UGameInstance> GameInstanceClass, const bool bGarbageCollectOnDestroy, const TMap<FString, FCVarConfig>& CVars)
     : GameInstanceClass{MoveTemp(GameInstanceClass)}
-    , LastInstanceId{0}
+    , LastPIEInstance{0}
     , bGarbageCollectOnDestroy{bGarbageCollectOnDestroy}
 {
 	if (NumScopedGames == 0)
@@ -77,7 +78,7 @@ FScopedGameInstance::FScopedGameInstance(TSubclassOf<UGameInstance> GameInstance
 FScopedGameInstance::FScopedGameInstance(FScopedGameInstance&& Other)
     : GameInstanceClass{MoveTemp(Other.GameInstanceClass)}
     , Games{MoveTemp(Other.Games)}
-    , LastInstanceId{Other.LastInstanceId}
+    , LastPIEInstance{Other.LastPIEInstance}
     , bGarbageCollectOnDestroy{Other.bGarbageCollectOnDestroy}
 {
 	++NumScopedGames;
@@ -109,14 +110,32 @@ FScopedGameInstance::~FScopedGameInstance()
 
 UGameInstance* FScopedGameInstance::CreateGame(const EScopedGameType Type, const FString& MapToLoad, const bool bWaitForConnect)
 {
-	auto Game = NewObject<UGameInstance>(GEngine, GameInstanceClass);
+	auto* Game = NewObject<UGameInstance>(GEngine, GameInstanceClass);
+	if (!ensureAlwaysMsgf(Game, TEXT("Failed to create game instance")))
+	{
+		return nullptr;
+	}
+
 	Games.Emplace(Game);
-	Game->InitializeStandalone();
+
+	const auto bRunAsDedicated = Type == EScopedGameType::Server;
+	const auto PIEInstance = ++LastPIEInstance;
+
+	if (auto* TestableGame = Cast<IUESTGameInstance>(Game))
+	{
+		TestableGame->InitializeForTests(bRunAsDedicated, PIEInstance);
+	}
+	else
+	{
+		IUESTGameInstance::DefaultInitializeForTests(*Game, bRunAsDedicated, PIEInstance);
+	}
 
 	auto* WorldContext = Game->GetWorldContext();
-	WorldContext->PIEInstance = ++LastInstanceId;
-	WorldContext->PIEPrefix = UWorld::BuildPIEPackagePrefix(WorldContext->PIEInstance);
-	WorldContext->RunAsDedicated = Type == EScopedGameType::Server;
+	if (!ensureAlways(WorldContext))
+	{
+		DestroyGame(Game);
+		return nullptr;
+	}
 
 	if (Type == EScopedGameType::Client)
 	{

diff --git a/Source/UEST/Private/ScopedGameTests.cpp b/Source/UEST/Private/ScopedGameTests.cpp
@@ -18,6 +18,7 @@ TEST(UEST, ScopedGame, Simple)
 		Tester.CreateClientFor(Server);
 	}
 
+
 	// You can access game worlds
 	UWorld* ServerWorld = Server->GetWorld();
 	ASSERT_THAT(ServerWorld, Is::Not::Null);

diff --git a/Source/UEST/Private/UESTGameInstance.cpp b/Source/UEST/Private/UESTGameInstance.cpp
@@ -0,0 +1,36 @@
+#include "UESTGameInstance.h"
+
+// God forgive me
+// UGameInstance::WorldContext is not public, and neither InitializeStandalone nor InitializeForPlayInEditor is suitable for us.
+// So we use this template hack to access WorldContext field.
+// Source: https://ledas.com/post/857-how-to-hack-c-with-templates-and-friends/
+template<FWorldContext* UGameInstance::* WorldContext>
+struct Stealer {
+	static friend FWorldContext*& FieldGetter(UGameInstance& GameInstance) {
+		return GameInstance.*WorldContext;
+	}
+};
+
+template struct Stealer<&UGameInstance::WorldContext>;
+static FWorldContext*& FieldGetter(UGameInstance&);
+
+void IUESTGameInstance::DefaultInitializeForTests(UGameInstance& GameInstance, const bool bRunAsDedicated, const int32 PIEInstance)
+{
+	constexpr auto WorldType = EWorldType::Game;
+
+	auto& WorldContext = GameInstance.GetEngine()->CreateNewWorldContext(WorldType);
+	WorldContext.OwningGameInstance = &GameInstance;
+	WorldContext.PIEInstance = PIEInstance;
+	WorldContext.PIEPrefix = UWorld::BuildPIEPackagePrefix(PIEInstance);
+
+	// We want to init this before calling UGameInstance::Init
+	WorldContext.RunAsDedicated = bRunAsDedicated;
+
+	FieldGetter(GameInstance) = &WorldContext;
+
+	auto* DummyWorld = UWorld::CreateWorld(WorldType, true);
+	DummyWorld->SetGameInstance(&GameInstance);
+	WorldContext.SetCurrentWorld(DummyWorld);
+
+	GameInstance.Init();
+}
diff --git a/Source/UEST/Public/ScopedGame.h b/Source/UEST/Public/ScopedGame.h
@@ -17,7 +17,7 @@ class UEST_API FScopedGameInstance : FNoncopyable
 
 	static void DestroyGameInternal(UGameInstance& Game);
 
-	int32 LastInstanceId;
+	int32 LastPIEInstance;
 
 	bool bGarbageCollectOnDestroy;
 

diff --git a/Source/UEST/Public/UESTGameInstance.h b/Source/UEST/Public/UESTGameInstance.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "UESTGameInstance.generated.h"
+
+UINTERFACE()
+class UEST_API UUESTGameInstance : public UInterface
+{
+	GENERATED_BODY()
+};
+
+/**
+ * Your GameInstance class can implement this interface if you want custom initialization in tests.
+ * If you don't, IUESTGameInstance::DefaultInitializeForTests is used.
+ */
+class UEST_API IUESTGameInstance
+{
+	GENERATED_BODY()
+public:
+
+	virtual void InitializeForTests(const bool bRunAsDedicated, int32 PIEInstance) = 0;
+
+	static void DefaultInitializeForTests(UGameInstance& GameInstance, bool bRunAsDedicated, int32 PIEInstance);
+};