最简单的 UE 4 C++ 教程 —— 注册组件的 hit 事件【十五】

我不是女神ヾ 2022-09-01 07:40 13阅读 0赞

**原教程是基于 UE 4.18，我是基于 UE 4.25】**

[英文原地址][Link 1]

接上一节教程，在本教程中，我们将学习如何在组件上注册一个 hit 事件。创建一个新的 C++ Actor 子类并将其命名为 **OnComponentHit** 。在头文件中，将声明一个 **UBoxComponent** 变量和一个当组件注册一个 hit 事件时运行的 void 函数。

下面是最终的头文件

### OnHitComponent.h ###

#pragma once
    
    #include "CoreMinimal.h"
    #include "GameFramework/Actor.h"
    #include "OnComponentHit.generated.h"
    
    UCLASS()
    class UNREALCPP_API AOnComponentHit : public AActor
    {
    	GENERATED_BODY()
    	
    public:	
    	// Sets default values for this actor's properties
    	AOnComponentHit();
    
    protected:
    	// Called when the game starts or when spawned
    	virtual void BeginPlay() override;
    
    public:	
    	// Called every frame
    	virtual void Tick(float DeltaTime) override;
    
    	UPROPERTY(VisibleAnywhere)
    	class UBoxComponent* MyComp;
    
    	UFUNCTION()
    	void OnCompHit(UPrimitiveComponent* HitComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, FVector NormalImpulse, const FHitResult& Hit);
    	
    };

在 .cpp 文件中，首先 \#include BoxComponent.h 头文件 。

#include "OnComponentHit.h"
    // include files
    #include "Components/BoxComponent.h"

接下来，我们将在 actor 的构造函数中为 actor 设置默认值。我们将用 **UBoxComponent** 初始化actor，并将其设置为 **RootComponent** 。然后，我们将添加 **OnComponentHit** 到组件，并将它连接到我们的 **OnCompHit** 函数。我们将在下一步创建 **OnCompHit （回调函数）**。我还将默认的 **CollisionProfileName** 设置为 **BlockAllDynamic** ，这可以稍后在编辑器中更改。

// Sets default values
    AOnComponentHit::AOnComponentHit()
    {
     	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    	PrimaryActorTick.bCanEverTick = true;
    
    	// Use a sphere as a simple collision representation
    	MyComp = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxComp"));
    	MyComp->SetSimulatePhysics(true);
        MyComp->SetNotifyRigidBodyCollision(true);
        
    	MyComp->BodyInstance.SetCollisionProfileName("BlockAllDynamic");
    	MyComp->OnComponentHit.AddDynamic(this, &AOnComponentHit::OnCompHit);
    
    	// Set as root component
    	RootComponent = MyComp;
    
    }

现在让我们创建简单的 **OnCompHit** 函数，当我们的 actor 撞击它时，它将打印并显示其他 actor 的名字到屏幕上。关于 **OnComponentHit** 的更多信息，你可以在访问一些不错的 AnswerHub [帖子1][1]、[帖子2][1]，或者在这里访问 ue4 [文档][Link 2]

void AOnComponentHit::OnCompHit(UPrimitiveComponent* HitComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, FVector NormalImpulse, const FHitResult& Hit)
    {
    	if ((OtherActor != NULL) && (OtherActor != this) && (OtherComp != NULL))
    	{
    		if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, FString::Printf(TEXT("I Hit: %s"), *OtherActor->GetName()));
    	}
    }

以下就是最终完整的 .cpp 文件

#include "OnComponentHit.h"
    #include "Components/BoxComponent.h"
    
    // Sets default values
    AOnComponentHit::AOnComponentHit()
    {
     	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    	PrimaryActorTick.bCanEverTick = true;
    
    	// Use a sphere as a simple collision representation
    	MyComp = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxComp"));
    	MyComp->SetSimulatePhysics(true);
    	MyComp->SetNotifyRigidBodyCollision(true);
    	MyComp->BodyInstance.SetCollisionProfileName("BlockAllDynamic");
    	MyComp->OnComponentHit.AddDynamic(this, &AOnComponentHit::OnCompHit);
    
    	// Set as root component
    	RootComponent = MyComp;
    
    }
    
    // Called when the game starts or when spawned
    void AOnComponentHit::BeginPlay()
    {
    	Super::BeginPlay();
    	
    }
    
    // Called every frame
    void AOnComponentHit::Tick(float DeltaTime)
    {
    	Super::Tick(DeltaTime);
    
    }
    
    void AOnComponentHit::OnCompHit(UPrimitiveComponent* HitComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, FVector NormalImpulse, const FHitResult& Hit)
    {
    	if ((OtherActor != NULL) && (OtherActor != this) && (OtherComp != NULL))
    	{
    		if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, FString::Printf(TEXT("I Hit: %s"), *OtherActor->GetName()));
    	}
    }

编译代码。将 actor 拖放到游戏场景中。添加一个静态网格到该 actor，并调整尺寸以适应 hit 框。当你按下 play 时，actor 应该注册 hit 事件。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70][]

运行的结果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70 1][]

[Link 1]: https://unrealcpp.com/on-component-hit/
[1]: https://answers.unrealengine.com/questions/429353/cpp-on-component-hit-doesnt-fire.html
[Link 2]: https://docs.unrealengine.com/latest/INT/API/Runtime/Engine/Components/UPrimitiveComponent/OnComponentHit/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70]: /images/20220829/dbb1fb122c4540ce996a647a81238a77.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70 1]: /images/20220829/d6bc261b75834d50bf9493773935de07.png