UE5 C++（十七）— 射线检测

前言

射线检测简单来说就是通过相机发射一条射线，用来检测对象的一种检测机制。
官网介绍：使用射线进行命中判定

这里主要介绍4种常用的射线检测方式。

根据通道进行射线检测

关键API：LineTraceSingleByChannel

声明变量
MyCharacter.h

	//射线检测
	FVector StartLocation;
	FVector EndLocation;
	FVector Direction;
	FHitResult HitResult;

在Tick中实现通道进行射线检测
MyCharacter.cpp

// Called every frame
void AMyCharacter::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

	StartLocation = MyCamera->GetComponentLocation();
	Direction = MyCamera->GetForwardVector();
	EndLocation = StartLocation + Direction * 1000.f;
	// 根据通道进行射线检测
	bool bHit = GetWorld()->LineTraceSingleByChannel(HitResult, StartLocation, EndLocation, ECC_Visibility); // 根据通道查询检测
	if (bHit)
	{
		AActor *HitActor = HitResult.GetActor();
		FVector ImpactPoint = HitResult.ImpactPoint;
		FVector HitLocation = HitResult.Location;
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("HitActor 1 :%s"), *HitActor->GetName()));
	}
}

编译 之后，在场景中添加CUBE运行

根据对象查询射线检测

关键API：LineTraceSingleByObjectType
声明变量
MyCharacter.h

	//射线检测
	FVector StartLocation;
	FVector EndLocation;
	FVector Direction;
	FHitResult HitResult;

在Tick中实现通道进行射线检测
MyCharacter.cpp

// Called every frame
void AMyCharacter::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

	StartLocation = MyCamera->GetComponentLocation();
	Direction = MyCamera->GetForwardVector();
	EndLocation = StartLocation + Direction * 1000.f;
	// 根据对象查询检测
	//添加通道 按指定对象检测，非指定指定对象是不会检测到的
	FCollisionObjectQueryParams ObjectQueryParams;
	ObjectQueryParams.AddObjectTypesToQuery(ECC_WorldStatic);
	bool bHit2 = GetWorld()->LineTraceSingleByObjectType(HitResult, StartLocation, EndLocation, ObjectQueryParams); // 根据对象查询检测
	if(bHit2)
	{
		AActor *HitActor = HitResult.GetActor();
		FVector ImpactPoint = HitResult.ImpactPoint;
		FVector HitLocation = HitResult.Location;
		GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("HitActor 2 :%s"), *HitActor->GetName()));
	}
}

编译 之后，在场景中添加CUBE运行

多通道射线检测

关键API：LineTraceMultiByChannel

声明变量
MyCharacter.h

	//射线检测
	FVector StartLocation;
	FVector EndLocation;
	FVector Direction;
	FHitResult HitResult;
	//多射线检测
	TArray<FHitResult> HitResults;

在Tick中实现通道进行射线检测
MyCharacter.cpp

// Called every frame
void AMyCharacter::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

	StartLocation = MyCamera->GetComponentLocation();
	Direction = MyCamera->GetForwardVector();
	EndLocation = StartLocation + Direction * 1000.f;
	// 根据多通道进行射线检测
		bool HitMuilt= GetWorld()->LineTraceMultiByChannel(HitResults, StartLocation, EndLocation, ECC_Visibility); // 多射线检测
	if (HitMuilt)
	{
		for (int32 i = 0; i < HitResults.Num(); i++)
		{
			AActor *HitActor = HitResults[i].GetActor();
			FVector ImpactPoint = HitResults[i].ImpactPoint;
			FVector HitLocation = HitResults[i].Location;
			GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("HitActor 3 :%s"), *HitActor->GetName()));
		}
	}
}

编译 之后，在场景中添加CUBE运行。

多射线对象查询检测

关键API：LineTraceMultiByObjectType

声明变量
MyCharacter.h

	//射线检测
	FVector StartLocation;
	FVector EndLocation;
	FVector Direction;
	FHitResult HitResult;
	//多射线检测
	TArray<FHitResult> HitResults;

在Tick中实现通道进行射线检测
MyCharacter.cpp

// Called every frame
void AMyCharacter::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

	StartLocation = MyCamera->GetComponentLocation();
	Direction = MyCamera->GetForwardVector();
	EndLocation = StartLocation + Direction * 1000.f;
	// 多射线对象查询检测
	FCollisionObjectQueryParams ObjectQueryParams;
	ObjectQueryParams.AddObjectTypesToQuery(ECC_WorldStatic);
	ObjectQueryParams.AddObjectTypesToQuery(ECC_WorldDynamic);
	bool HitMuilt2 = GetWorld()->LineTraceMultiByObjectType(HitResults, StartLocation, EndLocation, ObjectQueryParams); // 多射线检测
	if (HitMuilt2)
	{
		for (int32 i = 0; i < HitResults.Num(); i++)
		{
			AActor *HitActor = HitResults[i].GetActor();
			FVector ImpactPoint = HitResults[i].ImpactPoint;
			FVector HitLocation = HitResults[i].Location;
			GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("HitActor 4 :%s"), *HitActor->GetName()));
		}
	}
}

编译之后，要把CUBE设置为ECC_WorldDynamic 类型碰撞

在场景中运行，也是能正常打印的。