添加机关

首先向场景里面添加一个聚光源

添加聚光源以后，可以对其属性进行修改，如图：

然后需要给聚光源添加一个触发体积（TriggerVolume）。

然后调整触发体积的大小，按空格进行切换模式，移动旋转缩放

代码编写

所有引入的头文件都需要放在 #include “openDoor.generated.h” 之前。
定义ATriggerVolume的指针，添加UPROPERTY(EditAnywhere)，这样表示可以在任意地方赋值。
所以可以在界面上进行赋值。

#include <Engine/TriggerVolume.h>UPROPERTY(EditAnywhere)
ATriggerVolume* trigger;

赋值如图：
选中门，然后选中自定义的组件openDoor

编译完成，会添加Trigger

然后选中TriggerVolume即可。

划重点：
pawn = GetWorld()->GetFirstPlayerController()->GetPawn(); // 得到defaultPawn

这句代码不能放到构造函数里面，否则编译会造成虚幻的崩溃。

给密室添加屋顶

这里使用玻璃作为屋顶。

添加玻璃，然后使用缩放工具进行调整，盖满整个房间即可。

打印日志

UE4里面日志，使用UE_LOG，第一个参数默认是LogTemp，第二个参数是日志类型，警告是Warning，字符串使用TEXT() 括起来。
UE_LOG(LogTemp, Warning, TEXT("%s begin openDoor()"), *owner->GetName());

控制系统角色

运行，然后F8弹出，能看到一个DefaultPawn，这个是系统默认角色。

创建一个新游戏模式替换DefaultPawn

创建以后，指定pawn为刚才创建的对象。
运行，F8，pawn就是我们自定义的pawn了。

添加抓取组件

获取起点和终点

FVector start;FRotator viewRot;GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(start, viewRot);FVector end = start + viewRot.Vector() * 100; // 100cmDrawDebugLine(GetWorld(), start, end, FColor(255, 0, 0), false, 0.0f, 0, 10.0f);

物体拾取，碰撞属性设置

在检查碰撞的时候，只检测ECollisionChannel::ECC_PhysicsBody类别的物体。

设置物体属性：

今日完整代码

openDoor.h

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "openDoor.generated.h"class AActor;
class ATriggerVolume;
UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class MYPROJECT_API UopenDoor : public UActorComponent
{GENERATED_BODY()public:	// Sets default values for this component's propertiesUopenDoor();protected:// Called when the game startsvirtual void BeginPlay() override;public:	// Called every framevirtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;void openDoor();void closeDoor();private:AActor* owner;AActor* pawn;UPROPERTY(EditAnywhere)ATriggerVolume* trigger;float openTime = 0.4f;float lastTime = 0.0f;
};

openDoor.cpp

// Fill out your copyright notice in the Description page of Project Settings.#include "openDoor.h"
#include <GameFramework/Actor.h>
#include <Engine/TriggerVolume.h>
#include <Engine/World.h>// Sets default values for this component's properties
UopenDoor::UopenDoor()
{// Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features// off to improve performance if you don't need them.PrimaryComponentTick.bCanEverTick = true;
}// Called when the game starts
void UopenDoor::BeginPlay()
{Super::BeginPlay();/*	openDoor();*/owner = GetOwner();pawn = GetWorld()->GetFirstPlayerController()->GetPawn();  // 得到defaultPawnUE_LOG(LogTemp, Warning, TEXT("%s begin openDoor()"), *owner->GetName());
}// Called every frame
void UopenDoor::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{Super::TickComponent(DeltaTime, TickType, ThisTickFunction);if (nullptr != trigger && trigger->IsOverlappingActor(pawn)){openDoor();lastTime = GetWorld()->GetTimeSeconds();}if (GetWorld()->GetTimeSeconds() - lastTime > openTime){closeDoor();}
}void UopenDoor::openDoor()
{// pitch=y yaw=z roll=x
/*	FRotator newRotator = FRotator(0, 0, 0);*/FRotator newRotator = FRotator(0, 180, 0);owner->SetActorRotation(newRotator);
}void UopenDoor::closeDoor()
{// pitch=y yaw=z roll=xFRotator newRotator = FRotator(0, 90, 0);owner->SetActorRotation(newRotator);
}

grabber.h

// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"
#include "Components/ActorComponent.h"
#include "grabber.generated.h"UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
class MYPROJECT_API Ugrabber : public UActorComponent
{GENERATED_BODY()public:	// Sets default values for this component's propertiesUgrabber();protected:// Called when the game startsvirtual void BeginPlay() override;public:	// Called every framevirtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;private:FVector getLineStart();FVector getLineEnd();AActor* lineTrace();
};

grabber.cpp

// Fill out your copyright notice in the Description page of Project Settings.#include "grabber.h"
#include <Engine/World.h>
#include <DrawDebugHelpers.h>// Sets default values for this component's properties
Ugrabber::Ugrabber()
{// Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features// off to improve performance if you don't need them.PrimaryComponentTick.bCanEverTick = true;// ...
}// Called when the game starts
void Ugrabber::BeginPlay()
{Super::BeginPlay();// ...}// Called every frame
void Ugrabber::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
{Super::TickComponent(DeltaTime, TickType, ThisTickFunction);
}FVector Ugrabber::getLineStart()
{// 设置起点和终点，画射线FVector start;FRotator viewRot;GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(start, viewRot);return start;
}FVector Ugrabber::getLineEnd()
{FVector start;FRotator viewRot;GetWorld()->GetFirstPlayerController()->GetPlayerViewPoint(start, viewRot);return start + viewRot.Vector() * 100; // 100cm
}AActor* Ugrabber::lineTrace()
{// 检查碰撞FHitResult hit;GetWorld()->LineTraceSingleByObjectType(hit, getLineStart(), getLineEnd(), FCollisionObjectQueryParams(ECollisionChannel::ECC_PhysicsBody),FCollisionQueryParams(FName(TEXT(""), false, GetOwner()));AActor * act = hit.GetActor();if (nullptr != act){UE_LOG(LogTemp, Warning, TEXT(line hit : % s), *act->GetName());}return act;
}