UE4 Scripting with C++_04

青铜和钢铁比黄金和白银要坚硬

看视频固然快，但视频中其实没有书上涉及的点多

1、本节借助Packt Publishing - Intermediate Coding Concepts with Unreal Engine 4巩固Event和Delegate

01)、Event有二，在于重写 NotifyBeginOverlap和NotifyEndOvelap

02)、Delegate有三

1、在GameMode中声明Delegate,原因是GameMode的生命周期长
    在WorldSetting中选择GameMode使之生效
    DECLARE_DELEGATE(FStandardDelegateSignature)
    FStandardDelegateSignature CharacterVisualEffectsDelegateStart;
    FStandardDelegateSignature CharacterVisualEffectsDelegateStop;
2、获取GameMode并进行绑定，其中UGameplayStatics这个词记不住
    AUnrealScriptingBasicGameMode *MyGameMode = Cast<AUnrealScriptingBasicGameMode>(UGameplayStatics::GetGameMode(TheWorld));
    if (MyGameMode != nullptr) {
        MyGameMode->CharacterVisualEffectsDelegateStart.BindUObject(this,
	&AUnrealScriptingBasicCharacter::makeEFXVisible);
	MyGameMode->CharacterVisualEffectsDelegateStop.BindUObject(this,
	&AUnrealScriptingBasicCharacter::makeEFXInVisible);
	}
3、在EndPlay中解绑定
  	myGameMode->CharacterVisualEffectsDelegateStart.Unbind();
	myGameMode->CharacterVisualEffectsDelegateStop.Unbind();

03)、自定义Event

1、声明
	DECLARE_EVENT(APillSpawner,FPlayerEntered)
	FPlayerEntered OnPlayerEntered;
2、广播
        OnPlayerEntered.Broadcast();//没有智能提示，但编译通过
3、设置TriggerSource
	class APillSpawner* TriggerEventSource;
4、获取TriggerEventSource
        auto Itr = TActorIterator<APillSpawner>(GetWorld());
	TriggerEventSource = *Itr;
5、绑定TriggerEvent
        TriggerEventSource->OnPlayerEntered.AddUObject(
            this, &AMagicPill::OnTriggerEvent);
6、自定义OnTriggerEventn内容
        void AMagicPill::OnTriggerEvent()
    {
	PillEffect = FMath::RandRange(-150.f, 150.f);
	GEngine->AddOnScreenDebugMessage(-1, 5, FColor::Green,
	FString::Printf(TEXT("%f is my newValue"), PillEffect));
    }

2、本节借助Packt Publishing - Intermediate Coding Concepts with Unreal Engine 4学习Input

01)、Action和Axis Mapping

1、外设交互的手段，在project setting->engine->input中设置
Action Mapping有pressed和released状态
Axis Mapping则允许持续的输入
   在代码中绑定相应的动作函数
	PlayerInputComponent->BindAction("Jump", IE_Pressed, this, &ACharacter::Jump);
	PlayerInputComponent->BindAxis("MoveRight", this, &AUnrealScriptingBasicCharacter::MoveRight);

02)、关于Collsion有几点疑问还没有解决，下一节给出理解。

如果是一个场景中的物体，一般具备什么？什么决定了交互，什么决定了它的物理属性？如果要加collision componnet的话那又是什么决定了overlap属性呢等等。

3、再看书本

Chapter06:collision的理解强化

生词：
intersection：横断，横切; 交叉，相交; 交叉点，交叉线; [数] 交集; 
There are three classes of intersection for collisions
notifcation：通知; 通知单; 布告; 公布; 
Collisions that pass through each other without any notifcation
interpenetration：渗透，互相贯通
Collisions that prevent all interpenetration

1、三种碰撞Class：

Ignore:使得物体互相穿透
overlap:trigger the OnBeginOverlap and OnEndOverlap events
Block：使得物体不能够穿过

2、Actor是可以防止在场景中的，它可以有多个component，有一些component自身具备可以具备碰撞，而碰撞单独也可以作为组件加在Actor身上，这些component的collision通过设置，可以协调工作，例如对于一把剑，剑本身可以是block,all，外部再加一个长方体collision设置overlap，用于拾取操作。相对的，可以分析，吃鸡里面的捡枪，见子弹，地上的枪和子弹都是ovelap的，发生碰撞时可以触发拾取操作。另外西游记中的人参果对地面是ovelap或是ignore的。这里也说明了一点，对于碰撞，它有自己的形状。另外可以自定义物体对物体之间的碰撞属性。我可以看到你，或者无视你。

理解之后方便再看视频中的collision:

Character.h文件

      添加Overlap函数重写和PostInitializeComponents用于绑定
   UFUNCTION(BlueprintNativeEvent,Category=Collision)   
   void OnOverlapBegin(UPrimitiveComponent* comp, 
            AActor* otherActor, 
            UPrimitiveComponent* otherComp, 
            int32 otherBodyIndex, 
            bool bFromSweep,
             const FHitResult& SWeepResult);  
    virtual void PostInitializeComponents()override;

.c文件：

void AUnrealScriptingBasicCharacter::PostInitializeComponents() {
	Super::PostInitializeComponents();
	if (RootComponent) {
		GetCapsuleComponent()->OnComponentBeginOverlap.AddDynamic(this, &AUnrealScriptingBasicCharacter::OnOverlapBegin);
	}
}

void AUnrealScriptingBasicCharacter::OnOverlapBegin_Implementation(UPrimitiveComponent* comp, AActor* otherActor, UPrimitiveComponent* otherComp,
	int32 otherBodyIndex, bool bFromSweep, const FHitResult& SWeepResult){
	AMagicPill* isPill = Cast<AMagicPill>(otherActor);
	if (isPill != nullptr) {
		if (PickupMode) {
			GEngine->AddOnScreenDebugMessage(-1, 3, FColor::Blue,
				FString::Printf(TEXT("Colliding with %s"), *otherActor->GetName()));
			HP += isPill->getEffect();
			isPill->Destroy();
			GEngine->AddOnScreenDebugMessage(-1, 3, FColor::Blue,
				FString::Printf(TEXT("My Hp is %f"), HP));
			HPText->SetText(FText::FromString(FString::Printf(TEXT("HP:%.1f"), HP)));
		}}}

UE4 Scripting with C++_04

青铜和钢铁比黄金和白银要坚硬

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