今天讲解的是自定义事件的触发（Custom Event）。

在蓝图中是这个：

我们现在用代码来完成自定义事件的触发。这次我们并不使用GameModeBase类作为中介，而是就使用Trigger类充当中介，我们将其宏可以定义为EditAnywhere。

创建一个自定义事件，需要在UCLASS宏之前加上DECLARE_EVENT(类名, 自定义事件的名称，自己起即可)。

 1 #pragma once2 3 #include "CoreMinimal.h"4 #include "GameFramework/Actor.h"5 #include "Components\BoxComponent.h"6 #include "MyTrigger.generated.h"7 8 9 
10 DECLARE_EVENT(AMyTrigger, FPlayerEntered)
11 
12 UCLASS(Blueprintable,NotBlueprintType)
13 
14 class CUSTOMEVENT_API AMyTrigger : public AActor
15 {
16     GENERATED_BODY()
17     
18 public:    
19     // Sets default values for this actor's properties
20     AMyTrigger();
21 
22 protected:
23     // Called when the game starts or when spawned
24     virtual void BeginPlay() override;
25 
26 public:    
27     // Called every frame
28     virtual void Tick(float DeltaTime) override;
29 
30     UPROPERTY()
31     class UBoxComponent* box;
32 
33     UFUNCTION()
34     virtual void NotifyActorBeginOverlap(AActor* OtherActor) override;
35 
36     UFUNCTION()
37     virtual void NotifyActorEndOverlap(AActor* OtherActor) override;
38 
39 public:
40     FPlayerEntered onPlayerEntered;
41 };

以下是Trigger类的源文件：

 1 // Fill out your copyright notice in the Description page of Project Settings.2 3 4 #include "MyTrigger.h"5 6 // Sets default values7 AMyTrigger::AMyTrigger()8 {9      // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
10     PrimaryActorTick.bCanEverTick = true;
11     box = CreateDefaultSubobject<UBoxComponent>(TEXT("box"));
12     box->InitBoxExtent(FVector(50.0f));
13     RootComponent = box;
14 }
15 
16 // Called when the game starts or when spawned
17 void AMyTrigger::BeginPlay()
18 {
19     Super::BeginPlay();
20     
21 }
22 
23 // Called every frame
24 void AMyTrigger::Tick(float DeltaTime)
25 {
26     Super::Tick(DeltaTime);
27 
28 }
29 
30 void AMyTrigger::NotifyActorBeginOverlap(AActor* OtherActor)
31 {
32     onPlayerEntered.Broadcast();   //通过Broadcast()方法来通知运行其绑定的所有方法。
33 }
34 
35 void AMyTrigger::NotifyActorEndOverlap(AActor* OtherActor)
36 {
37     
38 }

以下是PointLight类的头文件代码：

 1 // Fill out your copyright notice in the Description page of Project Settings.2 3 #pragma once4 5 #include "CoreMinimal.h"6 #include "GameFramework/Actor.h"7 #include "MyTrigger.h"8 #include "Components\PointLightComponent.h"9 #include "MyListener.generated.h"
10 
11 UCLASS()
12 class CUSTOMEVENT_API AMyListener : public AActor
13 {
14     GENERATED_BODY()
15     
16 public:    
17     // Sets default values for this actor's properties
18     AMyListener();
19 
20 protected:
21     // Called when the game starts or when spawned
22     virtual void BeginPlay() override;
23 
24 public:    
25     // Called every frame
26     virtual void Tick(float DeltaTime) override;
27 
28 public:
29 
30     UPROPERTY()
31     class UPointLightComponent* pointLight;
32 
33     UPROPERTY(EditAnywhere)
34     AMyTrigger* eventSource;   //这里引入了Trigger类的指针，并将宏设定为EditAnywhere，需要在程序运行前进行手动加载。可以修改为自动加载。
35 
36     UFUNCTION()
37     void onTriggerEvent();
38 
39 };

以下是PointLight类的源文件代码：

 1 // Fill out your copyright notice in the Description page of Project Settings.2 3 4 #include "MyListener.h"5 6 // Sets default values7 AMyListener::AMyListener()8 {9      // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
10     PrimaryActorTick.bCanEverTick = true;
11     pointLight = CreateDefaultSubobject<UPointLightComponent>(TEXT("pointLight"));
12     RootComponent = pointLight;
13 }
14 
15 // Called when the game starts or when spawned
16 void AMyListener::BeginPlay()
17 {
18     Super::BeginPlay();
19 
20     if (eventSource) {
21         eventSource->onPlayerEntered.AddUObject(this,&AMyListener::onTriggerEvent);   //通过自定义事件的对象调用AddUObject函数绑定方法，而不是BindUObject方法。
22     }
23     
24 }
25 
26 // Called every frame
27 void AMyListener::Tick(float DeltaTime)
28 {
29     Super::Tick(DeltaTime);
30 
31 }
32 
33 void AMyListener::onTriggerEvent()
34 {
35     pointLight->SetLightColor(FLinearColor(FMath::RandRange(0,1), FMath::RandRange(0, 1), FMath::RandRange(0, 1)));
36 }

如果你很懒，不想手动选择，想这样自动选好。

那就这样改改：

1     TArray<AActor*> Lists;
2 
3     UGameplayStatics::GetAllActorsOfClass(GetWorld(), AMyTrigger::StaticClass(), Lists);
4
5     for (int i = 0; i < Lists.Num();i++) {  
6         AMyTrigger* trigger = Cast<AMyTrigger>(Lists[i]);  
7         if (trigger) {  
8            eventSource = trigger;  
9          } 
10     }

 效果如下：