UE4 全局数据（可变和不可变）

1.建立全局数据的访问（Game Singleton Class）（不变）

https://wiki.unrealengine.com/Global_Data_Access,_Data_Storage_Class_Accessible_From_Any_CPP_or_BP_Class_During_Runtime   

 

Game Singleton Class：

* 继承UObject,不能存放组件，而且运行中不可改变变量值；

*Project Settings->Engine->General

4.9 update: This is hidden, use the eye icon -> show advanced settings to see it!

 

2.在继承BlueprintFunctionLiabrary的C++里建立全部访问的变量和方法。（蓝图创建的不能创建静态成员变量）（可变）

 

3.GameInstance(可变)

https://wiki.unrealengine.com/Game_Instance,_Custom_Game_Instance_For_Inter-Level_Persistent_Data_Storage    //C++存储

https://docs.unrealengine.com/latest/INT/API/Runtime/Engine/Engine/UGameInstance/index.html   //C++API

 

示例：

UMySaveGame*LoadGameInstance=Cast<UMySaveGame>(UGameplayStatics::CreateSaveGameObject(UMySaveGame::StaticClass()));

LoadGameInstance=Cast<UMySaveGame>(UGameplayStatics::LoadGameFromSlot(LoadGameInstance->SaveSlotName, LoadGameInstance->UserIndex));

FString PlayerNameToDisplay = LoadGameInstance->PlayerName;

if (GEngine){

GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Yellow, PlayerNameToDisplay);

}