那里建设网站/热点新闻

原教程是基于 UE 4.18，我是基于 UE 4.25】

英文原地址

接上一节教程，在本教程中，当角色与一个触发器框（Trigger Box）发生重叠时将触发一个事件。

创建一个新的 C++ TriggerBox 子类【它继承自 TriggerBase 类，而它又继承自 Actor 类】并将其命名为 MyTriggerBox 。在头文件中添加 OnOverlapBegin 和 OnOverlapEnd 函数。

下面是最终的 .h 头文件【原教程的头文件代码错了，已修复】。

#pragma once#include "CoreMinimal.h"
#include "Engine/TriggerBox.h"
#include "MyTriggerBox.generated.h"/****/
UCLASS()
class HELLOUNREAL_API AMyTriggerBox : public ATriggerBox {GENERATED_BODY()protected:// Called when the game starts or when spawnedvirtual void BeginPlay() override;public:// constructor sets default values for this actor's propertiesAMyTriggerBox();// declare overlap begin functionUFUNCTION()void OnOverlapBegin(AActor* OverlappedActor, AActor* OtherActor);// declare overlap end functionUFUNCTION()void OnOverlapEnd(AActor* OverlappedActor, AActor* OtherActor);
};

在 .cpp 文件中，为了帮助我们可视化触发器框，我们必须 #include DrawDebugHelpers.h 文件。

#include "MyTriggerBox.h"
// include draw debu helpers header file
#include "DrawDebugHelpers.h"

我们也可以 #define 一些调试日志的快捷方式。

#define print(text) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 1.5, FColor::Green,text)
#define printFString(text, fstring) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, FString::Printf(TEXT(text), fstring))

在该 actor 的构造函数中，我们将向 OnActorBeginOverlap.AddDynamic 和 OnActorEndOverlap.AddDynamic 注册重叠事件。
 

AMyTriggerBox::AMyTriggerBox()
{//Register EventsOnActorBeginOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapBegin);OnActorEndOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapEnd);
}

在 BeginPlay 上，我们将使用 DrawDebugBox 绘制调试框。

void AMyTriggerBox::BeginPlay()
{Super::BeginPlay();DrawDebugBox(GetWorld(), GetActorLocation(), GetComponentsBoundingBox().GetExtent(), FColor::Purple, true, -1, 0, 5);}

接下来，我们将编写重叠函数，它将向屏幕打印一条消息，指示进入和退出触发器框的 actor 。

void AMyTriggerBox::OnOverlapBegin(class AActor* OverlappedActor, class AActor* OtherActor)
{// check if Actors do not equal nullptr and that if (OtherActor && (OtherActor != this)) {// print to screen using above defined method when actor enters trigger boxprint("Overlap Begin");printFString("Overlapped Actor = %s", *OverlappedActor->GetName());}
}void AMyTriggerBox::OnOverlapEnd(class AActor* OverlappedActor, class AActor* OtherActor)
{if (OtherActor && (OtherActor != this)) {// print to screen using above defined method when actor leaves trigger boxprint("Overlap Ended");printFString("%s has left the Trigger Box", *OtherActor->GetName());}
}

编译代码，将新 actor 拖放到游戏中，如下所示

 运行起来的框是这样的

下面是最后的 .cpp 文件。

#define print(text) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 1.5, FColor::Green,text)
#define printFString(text, fstring) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, FString::Printf(TEXT(text), fstring))#include "MyTriggerBox.h"
// include draw debu helpers header file
#include "DrawDebugHelpers.h"AMyTriggerBox::AMyTriggerBox()
{//Register EventsOnActorBeginOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapBegin);OnActorEndOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapEnd);
}// Called when the game starts or when spawned
void AMyTriggerBox::BeginPlay()
{Super::BeginPlay();DrawDebugBox(GetWorld(), GetActorLocation(), GetComponentsBoundingBox().GetExtent(), FColor::Purple, true, -1, 0, 5);}void AMyTriggerBox::OnOverlapBegin(class AActor* OverlappedActor, class AActor* OtherActor)
{// check if Actors do not equal nullptr and that if (OtherActor && (OtherActor != this)) {// print to screen using above defined method when actor enters trigger boxprint("Overlap Begin");printFString("Overlapped Actor = %s", *OverlappedActor->GetName());}
}void AMyTriggerBox::OnOverlapEnd(class AActor* OverlappedActor, class AActor* OtherActor)
{if (OtherActor && (OtherActor != this)) {// print to screen using above defined method when actor leaves trigger boxprint("Overlap Ended");printFString("%s has left the Trigger Box", *OtherActor->GetName());}
}

最后，按下播放键，操控玩家在触发器框里进进出出，得到的最终效果图如下所示。