How to detect if an Actor is IN or OUT a closed Spline?

[Avlu]

How to detect if an Actor is IN or OUT a closed Spline? I don´t know if there is a note or a setting for that.

[Everynone]

Same question?

How to get a grid system in a closed spline for a city builder game?

Do you know how I can fill the inside of a closed spline with a grid system. My Idea is that I can easily change the spline and my grid system changes with it. Also important to say is that the player shouldn´t be able to place buildings out of the spline and the player is only able to place buildings in the closed spline.

[Avlu]

Sounds like. This question just means the same, but without the grid system.

[amittelman]

[quote=“Avlu_, post:1, topic:1670073, full:true, username:Avlu”]
How to detect if an Actor is IN or OUT a closed Spline? I don´t know if there is a note or a setting for that.
[/quote]

Blockquote

You can try this code:

void ASplineEffectActor::SetupSpline()
{
	// Clear existing spline points and box components
	SplineComponent->ClearSplinePoints(false);
	for (UBoxComponent* BoxComponent : BoxComponents)
	{
		if (BoxComponent)
		{
			BoxComponent->DestroyComponent();
		}
	}
	BoxComponents.Empty();

	// Define spline points in World space
	FVector Points[4] = { FVector(0.f, 0.f, 0.f), FVector(100.f, 0.f, 0.f), FVector(100.f, 40.f, 0.f), FVector(0.f, 40.f, 0.f) };
	for (int32 i = 0; i < 4; i++)
	{
		SplineComponent->AddSplinePoint(Points[i], ESplineCoordinateSpace::Local, true);
	}
	SplineComponent->SetClosedLoop(true);
	SplineComponent->UpdateSpline();
}

void ASplineEffectActor::SetupMultipleSplineColliders()
{
	// Number of colliders per segment
	const int32 NumCollidersPerSegment = 5;

	// Clear previous box components
	for (UBoxComponent* BoxComponent : BoxComponents)
	{
		if (BoxComponent)
		{
			BoxComponent->DestroyComponent();
		}
	}
	BoxComponents.Empty();

	// Get total spline length
	float TotalSplineLength = SplineComponent->GetSplineLength();

	// Calculate desired distance between colliders
	float ColliderSpacing = TotalSplineLength / (NumCollidersPerSegment * SplineComponent->GetNumberOfSplinePoints());

	// Add multiple Box Colliders along the spline
	for (float DistanceAlongSpline = 0.0f; DistanceAlongSpline < TotalSplineLength - ColliderSpacing; DistanceAlongSpline += ColliderSpacing)
	{
		FVector StartLocation = SplineComponent->GetLocationAtDistanceAlongSpline(DistanceAlongSpline, ESplineCoordinateSpace::Local);
		FVector EndLocation = SplineComponent->GetLocationAtDistanceAlongSpline(DistanceAlongSpline + ColliderSpacing, ESplineCoordinateSpace::Local);
		FVector Center = (StartLocation + EndLocation) / 2.0f;
		FVector Direction = (EndLocation - StartLocation).GetSafeNormal();


		UE_LOG(LogTemp, Log, TEXT("DistanceAlongSpline: %f"), DistanceAlongSpline);
		UE_LOG(LogTemp, Log, TEXT("StartLocation: %s"), *StartLocation.ToString());
		UE_LOG(LogTemp, Log, TEXT("EndLocation: %s"), *EndLocation.ToString());
		UE_LOG(LogTemp, Log, TEXT("Center (before Z offset): %s"), *Center.ToString());
		UE_LOG(LogTemp, Log, TEXT("Direction: %s"), *Direction.ToString());

		// Offset the center slightly below the spline and make the box extend downward
		Center.Z -= 500.f; // Move the box slightly below the spline

		// Log the adjusted center location
		UE_LOG(LogTemp, Log, TEXT("Center (after Z offset): %s"), *Center.ToString());

		// Calculate the extent of the box
		float SplineWidth = 10.f; // Adjust based on your spline width
		FVector Extent = FVector(ColliderSpacing / 2.0f, SplineWidth, 510.f); // Adjust the Z extent as needed

		// Create a new box component
		UBoxComponent* BoxComponent = NewObject<UBoxComponent>(this, UBoxComponent::StaticClass());
		BoxComponent->SetWorldLocation(Center);
		BoxComponent->SetBoxExtent(Extent);

		// Set the box rotation to match the direction of the spline
		FRotator BoxRotation = Direction.Rotation();
		BoxComponent->SetWorldRotation(BoxRotation);

		// Attach the box to the spline component
		BoxComponent->SetupAttachment(SplineComponent);

		// Configure box collision properties
		BoxComponent->SetCollisionProfileName(TEXT("OverlapAllDynamic"));
		BoxComponent->OnComponentBeginOverlap.AddDynamic(this, &ASplineEffectActor::OnBoxOverlap);

		// Enable visibility for debugging
		BoxComponent->SetHiddenInGame(false);
		BoxComponent->SetVisibility(true);

		// Register the component with the world
		BoxComponent->RegisterComponent();

		// Add the box to the array of box components
		BoxComponents.Add(BoxComponent);

		// Create a debug text render component
		UTextRenderComponent* TextComponent = NewObject<UTextRenderComponent>(this);
		TextComponent->SetText(FText::FromString(FString::Printf(TEXT("Box %d"), BoxComponents.Num())));
		TextComponent->SetWorldSize(30.0f);
		TextComponent->SetupAttachment(BoxComponent);
		TextComponent->SetRelativeLocation(FVector(0.f, 0.f, 400.f)); // Adjust to position above the box
		TextComponent->SetHorizontalAlignment(EHorizTextAligment::EHTA_Center);

		// Register the text component
		TextComponent->RegisterComponent();

		//UE_LOG(LogTemp, Log, TEXT("BoxComponents.Num: %d"), *BoxComponents.Num());


	}
}

SetupSpline should be called from the constructor:

ASplineEffectActor::ASplineEffectActor()
{
	PrimaryActorTick.bCanEverTick = true;

	SetRootComponent(CreateDefaultSubobject<USceneComponent>("SceneRoot"));

	// Create Spline Component
	SplineComponent = CreateDefaultSubobject<USplineComponent>(TEXT("SplineComponent"));
	SplineComponent->SetupAttachment(RootComponent);
	SplineComponent->SetClosedLoop(true);

	SetupSpline();
}

SetupMultipleSplineColliders should be called from BeginPlay

basicly it created a wall of boxColliders around the spline which i can easily observe.

Hope it helps…