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[UE4] Subsystem, GameplayAbilityに関する講演で使用したC++コードについて

Last updated at Posted at 2021-10-05

はじめに

2021/10/2 に開催された「オンライン出張ヒストリア!ゲーム開発勉強会2021」にて、『目指せ脱UE4初心者!?知ってると開発が楽になる便利機能を紹介 DataAsset, Subsystem, GameplayAbility編 』というタイトルで講演をしました。

スライド:https://www.slideshare.net/historia_Inc/ue4-dataasset-subsystem-gameplayability
講演動画:https://www.youtube.com/watch?v=2L1Dor22Kjs

この講演ではSubsystem, GameplayAbilityを使うために必要なC++コードを紹介したのですが、オンライン上のスライドですとコピペがしづらいのでC++コード部分を抽出して記事化しました。

Subsystem

p68 GameInstance Subsystemの場合 - 準備 -

#pragma once

#include "CoreMinimal.h"
#include "Subsystems/GameInstanceSubsystem.h"
#include "MyGameInstanceSubsystem.generated.h"

UCLASS()
class ○○○_API UMyGameInstanceSubsystem
 : public UGameInstanceSubsystem
{
    GENERATED_BODY()

public:
    UFUNCTION(BlueprintCallable)
    int32 GetScore(){ return Score; }

private:
    int32 Score;
};

p74 BPから作成可能に(要コンパイル)

#pragma once

#include "CoreMinimal.h"
#include "Subsystems/WorldSubsystem.h"
#include "MyWorldSubsystem.generated.h"

UCLASS(Blueprintable, Abstract)
class ACTIONRPG_API UMyWorldSubsystem : public UWorldSubsystem
{
    GENERATED_BODY()

};

p82 拡張用BPのプロパティを持たせるには

#pragma once

#include "CoreMinimal.h"
#include "Subsystems/GameInstanceSubsystem.h"
#include "MyGameInstanceSubsystem.generated.h"

// 拡張用BPのベースとなるクラス
UCLASS(Abstract, Blueprintable, MinimalAPI, meta = (ShowWorldContextPin))
class UMyGameInstanceSubsystemHelperBase : public UObject
{
    GENERATED_BODY()
};

UCLASS()
class SUBSYSTEMBP_API UMyGameInstanceSubsystem : public UGameInstanceSubsystem
{
    GENERATED_BODY()

public:
    // 拡張用BPのプロパティ
    UPROPERTY(Transient, BlueprintReadWrite)
    UMyGameInstanceSubsystemHelperBase* SubsystemHelper;

};

p84 C++側で生成と設定をする手も ( .h側 )

#pragma once

#include "CoreMinimal.h"
#include "Subsystems/GameInstanceSubsystem.h"
#include "MyGameInstanceSubsystem.generated.h"

UCLASS(Abstract, Blueprintable, MinimalAPI, meta = (ShowWorldContextPin))
class UMyGameInstanceSubsystemHelperBase : public UObject
{
    GENERATED_BODY()
};

UCLASS()
class SUBSYSTEMBP_API UMyGameInstanceSubsystem : public UGameInstanceSubsystem
{
    GENERATED_BODY()

public:

    UMyGameInstanceSubsystem();

    virtual void Initialize(FSubsystemCollectionBase& Collection) override;
    virtual void Deinitialize() override;

    UPROPERTY(Transient, BlueprintReadOnly)
    UMyGameInstanceSubsystemHelperBase* SubsystemHelper;

private:
    TSubclassOf< class UMyGameInstanceSubsystemHelperBase > SubsystemHelperClass;
};

p85,86 C++側で生成と設定をする手も ( .cpp側 )

#include "MyGameInstanceSubsystem.h"
#include "Runtime/CoreUObject/Public/UObject/ConstructorHelpers.h"

UMyGameInstanceSubsystem::UMyGameInstanceSubsystem()
{
    // 拡張用BPのクラス情報を検索・取得。パスの指定には注意
    // .ini や プロジェクト設定でBPアセットのパスを設定できるようにしておくと親切
    static ConstructorHelpers::FClassFinder<UMyGameInstanceSubsystemHelperBase> BluePrintFile(TEXT("/Game/Subsystem/BP_MyGameInstanceSubsystemHelper"));
    if (BluePrintFile.Class) 
    {
        SubsystemHelperClass = (UClass*)BluePrintFile.Class;
    }
}

void UMyGameInstanceSubsystem::Initialize(FSubsystemCollectionBase& Collection)
{
    SubsystemHelper = nullptr;  

    if (SubsystemHelperClass)
    {
        // 拡張用BPを生成・設定
        SubsystemHelper = NewObject<UMyGameInstanceSubsystemHelperBase>(GetTransientPackage(), SubsystemHelperClass);
    }
}

void UMyGameInstanceSubsystem::Deinitialize()
{
    SubsystemHelper = nullptr;
}

p88 C++側で関数の準備をする場合

UCLASS(Abstract, Blueprintable, MinimalAPI, meta = (ShowWorldContextPin))
class UMyGameInstanceSubsystemHelperBase : public UObject
{
    GENERATED_BODY()

public:
    // 処理の中身はBP側で書くことを宣言
    UFUNCTION(BlueprintCallable, BlueprintImplementableEvent)
    void TestFunc();
};

Gameplay Ability

p130 .h側

#pragma once

#include "CoreMinimal.h"
#include "Kismet/BlueprintFunctionLibrary.h"
#include "AbilitySystemComponent.h"
#include "MyBlueprintFunctionLibrary.generated.h"

UCLASS()
class ACTIONRPG_API UMyBlueprintFunctionLibrary : public UBlueprintFunctionLibrary
{
    GENERATED_BODY()


    UFUNCTION(BlueprintCallable, meta = (DefaultToSelf = "Target"))
    static void GiveAbilityToComponent(AActor* Target, UAbilitySystemComponent* AbilitySystem, TArray<TSubclassOf<class UGameplayAbility>> AbilityList);

};

p131 .cpp側

#include "MyBlueprintFunctionLibrary.h"

void UMyBlueprintFunctionLibrary::GiveAbilityToComponent(AActor* Target, UAbilitySystemComponent* AbilitySystem, TArray<TSubclassOf<class UGameplayAbility>> AbilityList)
{
    if (AbilitySystem && Target)
    {
        int32 inputID(0);
        if (AbilityList.Num() > 0)
        {
            for (auto Ability : AbilityList) 
            {
                if (Ability)
                {
                    AbilitySystem->GiveAbility(FGameplayAbilitySpec(Ability.GetDefaultObject(), 1, inputID++));
                }
            }
        }
        AbilitySystem->InitAbilityActorInfo(Target, Target);
    }
}

p132 プロジェクト側の .Build.cs

PrivateDependencyModuleNames.AddRange(
new string[] {
    "GameplayAbilities"
    }
);

さいごに

DataAsset, Subystem, GameplayAbilityはいいぞ!

おしまい

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