UE5 C++ UGameInstance 功能、作用及应用

# UE5 C++ UGameInstance 功能及作用

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网上有很多文章介绍，例如在游戏中只有一个实例，换关卡不会丢失等。暂时省略。

# UE5 C++ UGameInstance 应用

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## 应用一，UE5 C++ UGameInstance 里监听player创建事件

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UWebSocketGameInstance.h里的定义

UCLASS()
class MYUE521_API UUWebSocketGameInstance : public UGameInstance
{

	GENERATED_BODY()


public:
	virtual void Init() override;
	virtual void Shutdown() override;
	void OnPlayerCreated(ULocalPlayer* player);
}

说明：

1. Init()方法是在UGameInstance.h里定义的。源码里的注解是允许在这里自定义一些实现
2. Shutdown()方法是在UGameInstance.h里定义的。源码里的注解是允许在这里自定义一些清理工作
3. void OnPlayerCreated(ULocalPlayer* player) 方法是我自己定义的方法，用来监听创建player以后执行的方法

下面来看一下实现UWebSocketGameInstance.cpp里

void UUWebSocketGameInstance::Init() {
	Super::Init();

	OnLocalPlayerAddedEvent.AddUObject(this,&UUWebSocketGameInstance::OnPlayerCreated);
  
}

void UUWebSocketGameInstance::Shutdown() {

	//先写自定义的清理工作
	 
	Super::Shutdown();
}

void UUWebSocketGameInstance::OnPlayerCreated(ULocalPlayer* player) {

	UE_LOG(LogTemp, Warning, TEXT("%s plaer is created"), *FString(__FUNCTION__));
}

说明：

1. UE5里的事件绑定，这里绑定到自定义的OnPlayerCreated 方法里
2. 触发事件OnLocalPlayerAddedEvent的位置在GameInstance.cpp里有AddLocalPlayer(ULocalPlayer* NewLocalPlayer, FPlatformUserId UserId)方法里有OnLocalPlayerAddedEvent.Broadcast(NewLocalPlayer); 通过广播通知

## 应用二，UE5 C++ UGameInstance 里player转成目标Characher的方法

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ACharacter* character = UGameplayStatics::GetPlayerCharacter(this->GetWorld(), 0);
Amyue521Character* character2 = Cast<Amyue521Character>(character);
if (character2 == nullptr) {
	UE_LOG(LogTemp, Warning, TEXT("%s  1强制类型转换成Amyue521Character失败"), *FString(__FUNCTION__));
}
else {
	
	UE_LOG(LogTemp, Warning, TEXT("%s  1强制类型转换成Amyue521Character成功"), *FString(__FUNCTION__));
}

## 应用三，UE5 C++ UGameInstance 里一些方法罗列

/** Returns number of fully registered local players */
int32					GetNumLocalPlayers() const;

/** Returns the local player at a certain index, or null if not found */
ULocalPlayer*			GetLocalPlayerByIndex(const int32 Index) const;

/** Returns the first local player, will not be null during normal gameplay */
ULocalPlayer*			GetFirstGamePlayer() const;

/** Returns the player controller assigned to the first local player. If World is specified it will search within that specific world */
APlayerController*		GetFirstLocalPlayerController(const UWorld* World = nullptr) const;

/** Returns the local player assigned to a physical Controller Id, or null if not found */
ULocalPlayer*			FindLocalPlayerFromControllerId(const int32 ControllerId) const;

/** Returns the local player assigned to this platform user id, or null if not found */
ULocalPlayer* FindLocalPlayerFromPlatformUserId(const FPlatformUserId UserId) const;

/** Returns the local player that has been assigned the specific unique net id */
ULocalPlayer*			FindLocalPlayerFromUniqueNetId(FUniqueNetIdPtr UniqueNetId) const;
ULocalPlayer*			FindLocalPlayerFromUniqueNetId(const FUniqueNetId& UniqueNetId) const;
ULocalPlayer*			FindLocalPlayerFromUniqueNetId(const FUniqueNetIdRepl& UniqueNetId) const;

/** Returns const iterator for searching list of local players */
TArray<ULocalPlayer*>::TConstIterator	GetLocalPlayerIterator() const;

/** Returns reference to entire local player list */
const TArray<ULocalPlayer*> &			GetLocalPlayers() const;

# UE5 C++ UGameInstance 其他

待补充