基于C++代码的UE4学习（三十）——蓝图的Construction Script与TIMER结合的控制Cube显现

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基于C++代码的UE4学习（三十）——蓝图的Construction Script与TIMER结合的控制Cube显现

 

这一节需要从三部分来讲，先讲解第一部分。

Construction与构造函数之间的关系。

构造函数是C++中的，Construction是蓝图中的，暂且理解为蓝图中的构造函数。

***但是，它们还是有区别的，Construction在C++中调用可以更改在构造函数中赋值好的属性值。

先定义一个ACTOR类，头文件内容如下，加粗的内容之前都学习过，这里不再赘述：

 

1 #include "CoreMinimal.h" 2 #include "GameFramework/Actor.h" 3 #include "MyActor.generated.h" 4 5 UCLASS() 6 class ONCONSTRUCTION_API AMyActor : public AActor 7 { 8 GENERATED_BODY() 9 10 public: 11 // Sets default values for this actor's properties 12 AMyActor(); 13 14 protected: 15 // Called when the game starts or when spawned 16 virtual void BeginPlay() override; 17 18 public: 19 // Called every frame 20 virtual void Tick(float DeltaTime) override; 21 22 virtual void EndPlay(EEndPlayReason::Type EndReason) override; 23 24 virtual void OnConstruction(const FTransform& Transform) override; 25 26 virtual void PostEditChangeProperty(FPropertyChangedEvent& PropertyChangedEvent) override; 27 28 UPROPERTY(EditAnywhere,BlueprintReadWrite) 29 bool show; 30 31 UPROPERTY() 32 class UStaticMeshComponent* myStaticMesh; 33 34 private: 35 36 FTIMERHandle myTimerHandle; 37 void setBomb(); 38 };

 

重点是源文件：

 

1 // Fill out your copyright notice in the DeScription page of Project Settings. 2 3 4 #include "MyActor.h" 5 #include "UObject/ConstructorHelpers.h" 6 #include "Components/StaticMeshComponent.h" 7 8 // Sets default values 9 AMyActor::AMyActor() 10 { 11 // Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it. 12 PrimaryActorTick.bCanEverTick = true; 13 myStaticMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("myStaticMesh")); 14 auto asset = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Engine/BasicShapes/Cube.Cube'")); 15 show = true; 16 if (asset.Succeeded()) { 17 myStaticMesh->SetStaticMesh(asset.Object); 18 myStaticMesh->SetMobility(EComponentMobility::Movable); 19 } 20 21 } 22 23 24 void AMyActor::OnConstruction(const FTransform& Transform) { 25 //在构造函数中的初始化的属性被更改时候的代码，写在这里，它将重新构造更新。 26 show = false; 27 myStaticMesh->SetVisibility(show); 28 } 29 30 void AMyActor::PostEditChangeProperty(FPropertyChangedEvent& events) 31 { 32 if (events.Property != nullptr) { 33 const FName propertyName = events.Property->GetFName(); 34 35 if (propertyName == GET_MEMBER_NAME_CHECKED(AMyActor, show)) { 36 myStaticMesh->SetVisibility(show); 37 } 38 } 39 } 40 41 42 43 // Called when the game starts or when spawned 44 void AMyActor::BeginPlay() 45 { 46 Super::BeginPlay(); 47 GetWorld()->GetTimerManager().SetTimer(myTimerHandle, this, &AMyActor::setBomb, 3.0f, true); 48 49 } 50 51 // Called every frame 52 void AMyActor::Tick(float DeltaTime) 53 { 54 Super::Tick(DeltaTime); 55 56 myStaticMesh->SetVisibility(show); 57 58 } 59 60 void AMyActor::EndPlay(EEndPlayReason::Type EndReason) 61 { 62 GetWorld()->GetTimerManager().ClearTimer(myTimerHandle); 63 } 64 65 void AMyActor::setBomb() { 66 show = !show; 67 }

 

 

构造函数是AMyActor，在里面将show属性设置为了true，这样会导致Cube在被构造的时候，是看得见的。

但是在OnConstruction函数中将show属性设置为了false。这样会导致Cube在被构造的时候，又成了看不见的。

 

1 AMyActor::AMyActor() 2 { 3 // Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it. 4 PrimaryActorTick.bCanEverTick = true; 5 myStaticMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("myStaticMesh")); 6 auto asset = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Engine/BasicShapes/Cube.Cube'")); 7 show = true; 8 if (asset.Succeeded()) { 9 myStaticMesh->SetStaticMesh(asset.Object); 10 myStaticMesh->SetMobility(EComponentMobility::Movable); 11 } 12 13 } 14 15 16 void AMyActor::OnConstruction(const FTransform& Transform) { 17 //在构造函数中的初始化的属性被更改时候的代码，写在这里，它将重新构造更新。 18 show = false; 19 myStaticMesh->SetVisibility(show); 20 }

 

第二部分，我们将手动控制show属性，人为操纵将其可见与否进行设置。这里需要说明的是，PostEditChangeProperty方法只能相应人为操作（目前只实验出如此，如果可以自动的话，一定有别的方法，而我现在还不清楚，希望知道的可以告诉我，先谢谢了）

 

1 void AMyActor::PostEditChangeProperty(FPropertyChangedEvent& events) 2 { 3 if (events.Property != nullptr) { 4 const FName propertyName = events.Property->GetFName(); 5 6 if (propertyName == GET_MEMBER_NAME_CHECKED(AMyActor, show)) { 7 myStaticMesh->SetVisibility(show); 8 } 9 } 10 }

 

 

第三部分，我不想手动控制，加一个Timer，用计时器来帮忙显示和关闭显示。

 

1 void AMyActor::BeginPlay() 2 { 3 Super::BeginPlay(); 4 GetWorld()->GetTimerManager().SetTimer(myTimerHandle, this, &AMyActor::setBomb, 3.0f, true); 5 6 } 7 8 void AMyActor::setBomb() { 9 show = !show; 10 } 11 12 void AMyActor::Tick(float DeltaTime) 13 { 14 Super::Tick(DeltaTime); 15 16 myStaticMesh->SetVisibility(show); 17 18 }

 

 

这里是放在Tick里去不断调用SetVisibility方法的，这一点很重要，因为PostEditChangeProperty方法无法响应Timer对属性的改变。

每隔三秒，show的值会取反，会改变，从而造成效果的改变，此时手动点击show属性一样可以改变。

 

 

本文标签： 蓝图代码ConstructionTimerScript