最简单的 UE 4 C++ 教程 —— 触发区域的灯光切换【二十三】

怼烎@ 2022-09-01 15:56 176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，**本教程需要注意的是**，需要确保第一人称的 Character 是纯净的，即没有《[最简单的 UE 4 C++ 教程 —— 为 Charactor 添加重叠事件【十九】][UE 4 C_ _ _ _ Charactor]》添加的代码，否则触发灯光的开关可能会有冲突。

在本教程中，我们将创建一个灯，当用户进入 actor 的 **USphereComponent** 时，它会打开或关闭。创建一个新的 C++ 角色类并将其命名为 **LightSwitchTrigger** 。在头文件中，我们将定义我们的 **PointLight**、**USphereComponent**、**Overlap** 函数和 **ToggleLight** 函数。

### LightSwitchTrigger.h ###

#pragma once
    
    #include "CoreMinimal.h"
    #include "GameFramework/Actor.h"
    #include "LightSwitchTrigger.generated.h"
    
    UCLASS()
    class UNREALCPP_API ALightSwitchTrigger : public AActor
    {
    	GENERATED_BODY()
    	
    public:	
    	// Sets default values for this actor's properties
    	ALightSwitchTrigger();
    
    protected:
    	// Called when the game starts or when spawned
    	virtual void BeginPlay() override;
    
    public:	
    	// Called every frame
    	virtual void Tick(float DeltaTime) override;
    
    	// declare point light comp
    	UPROPERTY(VisibleAnywhere, Category = "Light Switch")
    	class UPointLightComponent* PointLight;
    
    	// declare sphere comp
    	UPROPERTY(VisibleAnywhere, Category = "Light Switch")
    	class USphereComponent* LightSphere;
    
    	// declare light intensity variable
    	UPROPERTY(VisibleAnywhere, Category = "Light Switch")
    	float LightIntensity;
    	
    	// declare overlap begin function
    	UFUNCTION()
    	void OnOverlapBegin(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult);
    
    	// declare overlap end function
    	UFUNCTION()
    	void OnOverlapEnd(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex);
    
    	// declare ToggleLight function
    	UFUNCTION()
    	void ToggleLight();
    };

接下来，在 .cpp 中，我们将 **\#include DrawDebuHelpers.h** 来帮助我们可视化碰撞球体。

在 **LightSwitchTrigger** 初始函数中，我们将把光照强度设置为 3000.0f。接下来，我们将添加一个 **PointLight** 作为我们的 **RootComponent** 。然后，我们将为触发器球体 的 actor 添加一个**USphereComponent （LightSphere）**，并将其附加到 **RootComponent** 。然后将 **USphereComponent** 连接到我们稍后将创建的 **Overlap** 函数。

### 设置触发器中的灯光 ###

ALightSwitchTrigger::ALightSwitchTrigger()
    {
     	// 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;
    
    	LightIntensity = 3000.0f;
    
    	PointLight = CreateDefaultSubobject<UPointLightComponent>(TEXT("Point Light"));
    	PointLight->Intensity = LightIntensity;
    	//PointLight->bVisible = true; 过时
        //PointLight->SetVisibleFlag(true);
        PointLight->SetVisibility(true);
    	RootComponent = PointLight;
    
    	LightSphere = CreateDefaultSubobject<USphereComponent>(TEXT("Light Sphere Component"));
    	LightSphere->InitSphereRadius(300.0f);
    	LightSphere->SetCollisionProfileName(TEXT("Trigger"));
    	LightSphere->SetupAttachment(RootComponent);
    
    	LightSphere->OnComponentBeginOverlap.AddDynamic(this, &ALightSwitchTrigger::OnOverlapBegin);
    	LightSphere->OnComponentEndOverlap.AddDynamic(this, &ALightSwitchTrigger::OnOverlapEnd); 
    
    }

在 **BeginPlay()** 中添加一个与 **LightSphere** 半径相同的调试球体。

void ALightSwitchTrigger::BeginPlay()
    {
    	Super::BeginPlay();
    
    	DrawDebugSphere(GetWorld(), GetActorLocation(), 300.f, 50, FColor::Green, true, -1, 0, 2);
    	
    }

创建一个名为 **ToggleLight()** 的函数，用于切换 **PointLight** 的可见性。

void ALightSwitchTrigger::ToggleLight()
    {
        PointLight->ToggleVisibility();
    }

接下来，我们将创建两个重叠函数，它们都调用 ToggleLight 函数来切换灯光的可见性。

void ALightSwitchTrigger::OnOverlapBegin(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)
    {
        if (OtherActor && (OtherActor != this) && OtherComp)
        {
            ToggleLight();
        }
    }
    
    void ALightSwitchTrigger::OnOverlapEnd(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex)
    {
        if (OtherActor && (OtherActor != this) && OtherComp)
        {
            ToggleLight();
        }
    }

完整的 cpp 代码如下

#include "LightSwitchTrigger.h"
    #include "Components/PointLightComponent.h"
    #include "Components/SphereComponent.h"
    // include draw debu helpers header file
    #include "DrawDebugHelpers.h"
    
    // Sets default values
    ALightSwitchTrigger::ALightSwitchTrigger()
    {
     	// 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;
    
    	LightIntensity = 3000.0f;
    
    	PointLight = CreateDefaultSubobject<UPointLightComponent>(TEXT("Point Light"));
    	PointLight->Intensity = LightIntensity;
    	PointLight->bVisible = true;
    	RootComponent = PointLight;
    
    	LightSphere = CreateDefaultSubobject<USphereComponent>(TEXT("Light Sphere Component"));
    	LightSphere->InitSphereRadius(300.0f);
    	LightSphere->SetCollisionProfileName(TEXT("Trigger"));
    	LightSphere->SetupAttachment(RootComponent);
    
    	LightSphere->OnComponentBeginOverlap.AddDynamic(this, &ALightSwitchTrigger::OnOverlapBegin);
    	LightSphere->OnComponentEndOverlap.AddDynamic(this, &ALightSwitchTrigger::OnOverlapEnd); 
    
    }
    
    // Called when the game starts or when spawned
    void ALightSwitchTrigger::BeginPlay()
    {
    	Super::BeginPlay();
    
    	DrawDebugSphere(GetWorld(), GetActorLocation(), 300.f, 50, FColor::Green, true, -1, 0, 2);
    	
    }
    
    // Called every frame
    void ALightSwitchTrigger::Tick(float DeltaTime)
    {
    	Super::Tick(DeltaTime);
    
    }
    
    void ALightSwitchTrigger::OnOverlapBegin(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)
    {
        if (OtherActor && (OtherActor != this) && OtherComp)
        {
            ToggleLight();
        }
    }
    
    void ALightSwitchTrigger::OnOverlapEnd(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex)
    {
        if (OtherActor && (OtherActor != this) && OtherComp)
        {
            ToggleLight();
        }
    }
    
    void ALightSwitchTrigger::ToggleLight()
    {
        PointLight->ToggleVisibility();
    }

最后，编译代码并将 **LightSwitchTrigger** 拖到场景中。现在当玩家进入球体区域时，灯光就会切换开启状态。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70][] 放置触发区域到场景中

游戏运行的效果图：进入触发区域关闭灯光，离开触发区域开启灯光

![20210729035544944.gif][] 进进出出触发区域以切换灯光的开启状态

[Link 1]: https://unrealcpp.com/light-switch-trigger/
[UE 4 C_ _ _ _ Charactor]: https://panda1234lee.blog.csdn.net/article/details/119152036
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BhbmRhMTIzNGxlZQ_size_16_color_FFFFFF_t_70]: /images/20220829/a7fd57c0a1f642fea682fbf233735ccb.png
[20210729035544944.gif]: /images/20220829/0f9ab121b9224eeb8f9a9068f4673082.png