[Unreal] singleton UGameInstance와 interface의 활용 예시

1. 게임인스턴스

 

.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "Engine/GameInstance.h"
#include "SGameInstance.generated.h"

/**
 * 
 */
UCLASS()
class TRACESOFTHEFOX_API USGameInstance : public UGameInstance
{
	GENERATED_BODY()
public:
	USGameInstance();
	virtual void Init() override;
	virtual void Shutdown() override;
};

.cpp

// Fill out your copyright notice in the Description page of Project Settings.


#include "Game/SGameInstance.h"
#include "Kismet/KismetSystemLibrary.h"

USGameInstance::USGameInstance()
{
}

void USGameInstance::Init()
{
	Super::Init();
	UE_LOG(LogTemp, Log, TEXT("USGameInstance Init"));
    UKismetSystemLibrary::PrintString(this, TEXT("USGameInstance this Init"));
	// this 대신 GetWorld 가능
	UKismetSystemLibrary::PrintString(GetWorld(), TEXT("USGameInstance GetWorld Init"));
}

void USGameInstance::Shutdown()
{
	Super::Shutdown();
	UE_LOG(LogTemp, Log, TEXT("USGameInstance Shutdown"));
    UKismetSystemLibrary::PrintString(this, TEXT("USGameInstance this Shutdown"));
	// this 대신 GetWorld 가능
	UKismetSystemLibrary::PrintString(GetWorld(), TEXT("USGameInstance GetWorld Shutdown")); // 월드 객체를 가져올 수 있는 액터들 같은 경우 가능
}

2. 인터페이스

끼워넣을 수 있는 ‘행동’

생성해서 만들면 Uclass 와 Iclass가 있다.

.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "UObject/Interface.h"
#include "SFlyable.generated.h"

// This class does not need to be modified.
UINTERFACE(MinimalAPI)
class USFlyable : public UInterface
{
	GENERATED_BODY()
};

/**
 * 
 */
class TRACESOFTHEFOX_API ISFlyable
{
	GENERATED_BODY()

	// Add interface functions to this class. This is the class that will be inherited to implement this interface.
public:
	virtual void Fly() = 0;
	// 이렇게 '순수 가상 함수'가 들어있는 클래스를 인터페이스라고 한다.
};

새로 object 클래스를 일단 상속받은 c++ 클래스를 만든다.

.h

// Fill out your copyright notice in the Description page of Project Settings.

#pragma once

#include "CoreMinimal.h"
#include "UObject/NoExportTypes.h"
#include "SFlyable.h" // 상속하기 위해 가져옴
#include "SPigeon.generated.h"

/**
 * 
 */
UCLASS()
class TRACESOFTHEFOX_API USPigeon : public UObject, public ISFlyable // 인터페이스 상속
{
	GENERATED_BODY()
public:
	USPigeon(); // 생성자
	virtual void Fly() override; 
private:
	UPROPERTY()
	FString Name;
};

피죤 cpp

// Fill out your copyright notice in the Description page of Project Settings.


#include "Examples/SPigeon.h"

USPigeon::USPigeon()
{
	Name = TEXT("Pigeon");
}

void USPigeon::Fly()
{
	UE_LOG(LogTemp, Log, TEXT("%s is now Flying"), *Name)
}

싱글톤에 추가해본다.

// Fill out your copyright notice in the Description page of Project Settings.


#include "Game/SGameInstance.h"
#include "Kismet/KismetSystemLibrary.h"
#include "Examples/SFlyable.h"
#include "Examples/SPigeon.h"

USGameInstance::USGameInstance()
{
}

void USGameInstance::Init()
{
	Super::Init();
	UE_LOG(LogTemp, Log, TEXT("USGameInstance Init"));
	UKismetSystemLibrary::PrintString(this, TEXT("USGameInstance this Init"));
	// this 대신 GetWorld
	UKismetSystemLibrary::PrintString(GetWorld(), TEXT("USGameInstance GetWorld Init"));

	USPigeon* pigeon1 = NewObject<USPigeon>();
	ISFlyable* Bird1 = Cast<ISFlyable>(pigeon1);
	//현업에서 인터페이스 개념은 대부분 이런 식으로 업캐스팅 하기 위함
	if (nullptr != Bird1) {
		Bird1->Fly();
	}
}

void USGameInstance::Shutdown()
{
	Super::Shutdown();
	UE_LOG(LogTemp, Log, TEXT("USGameInstance Shutdown"));
	UKismetSystemLibrary::PrintString(this, TEXT("USGameInstance this Shutdown"));
	// this 대신 GetWorld
	UKismetSystemLibrary::PrintString(GetWorld(), TEXT("USGameInstance GetWorld Shutdown")); // 월드 객체를 가져올 수 있는 액터들 같은 경우 가능
}