最简单的 UE 4 C++ 教程 —— 触发器框【二十】
【摘要】
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 ...
原教程是基于 UE 4.18，我是基于 UE 4.25】
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】。
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#pragma once
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#include "CoreMinimal.h"
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#include "Engine/TriggerBox.h"
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#include "MyTriggerBox.generated.h"
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/**
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*
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*/
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UCLASS()
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class HELLOUNREAL_API AMyTriggerBox : public ATriggerBox {
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GENERATED_BODY()
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protected:
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// Called when the game starts or when spawned
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virtual void BeginPlay() override;
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public:
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// constructor sets default values for this actor's properties
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AMyTriggerBox();
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// declare overlap begin function
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UFUNCTION()
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void OnOverlapBegin(AActor* OverlappedActor, AActor* OtherActor);
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// declare overlap end function
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UFUNCTION()
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void OnOverlapEnd(AActor* OverlappedActor, AActor* OtherActor);
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};
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。
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#include "MyTriggerBox.h"
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// include draw debu helpers header file
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#include "DrawDebugHelpers.h"
我们也可以 #define 一些调试日志的快捷方式。
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#define print(text) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 1.5, FColor::Green,text)
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#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。
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AMyTriggerBox::AMyTriggerBox()
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{
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//Register Events
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OnActorBeginOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapBegin);
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OnActorEndOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapEnd);
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}
在 BeginPlay 上，我们将使用 DrawDebugBox 绘制调试框。
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void AMyTriggerBox::BeginPlay()
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{
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Super::BeginPlay();
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DrawDebugBox(GetWorld(), GetActorLocation(), GetComponentsBoundingBox().GetExtent(), FColor::Purple, true, -1, 0, 5);
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}
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 。
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void AMyTriggerBox::OnOverlapBegin(class AActor* OverlappedActor, class AActor* OtherActor)
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{
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// check if Actors do not equal nullptr and that
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if (OtherActor && (OtherActor != this)) {
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// print to screen using above defined method when actor enters trigger box
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print("Overlap Begin");
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printFString("Overlapped Actor = %s", *OverlappedActor->GetName());
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}
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}
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void AMyTriggerBox::OnOverlapEnd(class AActor* OverlappedActor, class AActor* OtherActor)
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{
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if (OtherActor && (OtherActor != this)) {
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// print to screen using above defined method when actor leaves trigger box
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print("Overlap Ended");
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printFString("%s has left the Trigger Box", *OtherActor->GetName());
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}
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}
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。
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#define print(text) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 1.5, FColor::Green,text)
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#define printFString(text, fstring) if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Green, FString::Printf(TEXT(text), fstring))
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#include "MyTriggerBox.h"
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// include draw debu helpers header file
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#include "DrawDebugHelpers.h"
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AMyTriggerBox::AMyTriggerBox()
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{
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//Register Events
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OnActorBeginOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapBegin);
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OnActorEndOverlap.AddDynamic(this, &AMyTriggerBox::OnOverlapEnd);
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}
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// Called when the game starts or when spawned
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void AMyTriggerBox::BeginPlay()
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{
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Super::BeginPlay();
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DrawDebugBox(GetWorld(), GetActorLocation(), GetComponentsBoundingBox().GetExtent(), FColor::Purple, true, -1, 0, 5);
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}
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void AMyTriggerBox::OnOverlapBegin(class AActor* OverlappedActor, class AActor* OtherActor)
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{
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// check if Actors do not equal nullptr and that
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if (OtherActor && (OtherActor != this)) {
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// print to screen using above defined method when actor enters trigger box
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print("Overlap Begin");
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printFString("Overlapped Actor = %s", *OverlappedActor->GetName());
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}
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}
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void AMyTriggerBox::OnOverlapEnd(class AActor* OverlappedActor, class AActor* OtherActor)
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{
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if (OtherActor && (OtherActor != this)) {
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// print to screen using above defined method when actor leaves trigger box
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print("Overlap Ended");
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printFString("%s has left the Trigger Box", *OtherActor->GetName());
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}
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}
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。
文章来源: panda1234lee.blog.csdn.net，作者：panda1234lee，版权归原作者所有，如需转载，请联系作者。
原文链接：panda1234lee.blog.csdn.net/article/details/119186637
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