file
namespace    UE::VirtualCamera::Private
function     static TTuple<int32, int32, TArray<HHitProxy*>> GetProxyMap

	 * @see FViewport::GetHitProxyMap.
	 */
	static TTuple<int32, int32, TArray<HHitProxy*>> GetProxyMap(FViewport& Viewport, const FVector2D& InScreenPosition, const uint32 HitProxySize)
	{
		// See FViewport::GetHitProxy.
		// Compute a HitProxySize x HitProxySize test region with the center at (X,Y).
		int32 MinX = InScreenPosition.X - HitProxySize;
		int32 MinY = InScreenPosition.Y - HitProxySize;
		int32 MaxX = InScreenPosition.X + HitProxySize;
		int32 MaxY = InScreenPosition.Y + HitProxySize;
		
		// Clip the region to the viewport bounds.
		const FIntPoint ViewportSize = Viewport.GetSizeXY();
		MinX = FMath::Clamp(MinX, 0, ViewportSize.X - 1);
		MinY = FMath::Clamp(MinY, 0, ViewportSize.Y - 1);
		MaxX = FMath::Clamp(MaxX, 0, ViewportSize.X - 1);

file
namespace    UE::VirtualCamera::Private
function     static void EnumerateHitProxies

		FViewport& Viewport,
		const FVector2D& InScreenPosition,
		const uint32 HitProxySize,
		TFunctionRef<EBreakBehaviour(const UPrimitiveComponent& Component)> Callback
		)
	{
		auto[TestSizeX, TestSizeY, ProxyMap] = GetProxyMap(Viewport, InScreenPosition, HitProxySize);
		if (ProxyMap.IsEmpty())
		{
			return;
		}
		
		const auto ProcessProxy = [&Callback](HHitProxy* Proxy) -> EBreakBehaviour

file
function     bool UVCamBlueprintFunctionLibrary::MultiTraceHitProxyOnViewport

	using namespace UE::VirtualCamera::Private;
	TArray<FVCamTraceHitProxyResult> HitResults;
	EnumerateHitProxies(*Viewport, InScreenPosition, FMath::Max(InQueryParams.HitProxySize, 0), [&InQueryParams, &HitResults](const UPrimitiveComponent& Component)
	{
		if (PassesFilters(Component, InQueryParams))
		{
			// Component is in a HActor proxy, which keeps a const reference. We cannot safely use const_cast without invoking undefined behavior.
			// Hence we must resort to this runtime search hack.
			TArray<UActorComponent*> Components = Component.GetOwner()->GetComponents().Array();

	/** Determine the size of the query area around the center pixel. */
	UPROPERTY(EditAnywhere, BlueprintreadWrite, Category = "VirtualCamera")
	int32 HitProxySize = 5;

	/** Components on these actors should not be considered. */
	UPROPERTY(EditAnywhere, BlueprintreadWrite, Category = "VirtualCamera")
	TArray<AActor*> IgnoredActors;
};

file
function     class VIRTUALCAMERA_API UVCamBlueprintFunctionLibrary : public UBlueprintFunctionLibrary { GENERATED_BODY

	/**
	 * Traces from the viewport and returns all components that contribute to the pixels surrounding InScreenPosition.
	 * The size of the pixel area checked is controlled by InQueryParams.HitProxySize.
	 * 
	 * This finds actors that have NoCollision set. The actor is found by determining which actors contribute to the specified pixel.
	 * This function is designed for Editor builds; in Runtime builds, it returns false.
	 *
	 * @param InScreenPosition The viewport position to trace
	 * @param InTargetViewport The viewport to trace in
	 * @param InQueryParams Parameters for how the actors should be queried
	 * @param Result The result, set if this function returns true.
	 *
	 * @return Whether Result was written to
	 */
	UFUNCTION(BlueprintPure, Category = "VirtualCamera")
	static bool MultiTraceHitProxyOnViewport(const FVector2D& InScreenPosition, EVCamTargetViewportID InTargetViewport, FVCamTraceHitProxyQueryParams InQueryParams, TArray<FVCamTraceHitProxyResult>& Result);

private:

#if WITH_EDITOR
	/** Returns the current sequencer. */
	static TWeakPtr<ISequencer> GetSequencer();

file
function     FViewport::FViewport

{
	//initialize the hit proxy kernel
	HitProxySize = 5;
	if (GIsEditor) 
	{
		GConfig->GetInt( TEXT("UnrealEd.HitProxy"), TEXT("HitProxySize"), (int32&)HitProxySize, GEditorIni );
		HitProxySize = FMath::Clamp( HitProxySize, (uint32)1, (uint32)MAX_HITPROXYSIZE );
	}

	// Cache the viewport client's hit proxy storage requirement.
	bRequiresHitProxyStorage = ViewportClient && ViewportClient->RequiresHitProxyStorage();
#if !WITH_EDITOR && !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	if ( bRequiresHitProxyStorage )

file
function     HHitProxy* FViewport::GetHitProxy

HHitProxy* FViewport::GetHitProxy(int32 X,int32 Y)
{
	// Compute a HitProxySize x HitProxySize test region with the center at (X,Y).
	int32	MinX = X - HitProxySize,
			MinY = Y - HitProxySize,
			MaxX = X + HitProxySize,
			MaxY = Y + HitProxySize;

	FIntPoint VPSize = GetSizeXY();
	
	// Clip the region to the viewport bounds.
	MinX = FMath::Clamp(MinX, 0, VPSize.X - 1);
	MinY = FMath::Clamp(MinY, 0, VPSize.Y - 1);

file
class        class FViewport : public FRenderTarget, protected FRenderResource

	/** The size of the region to check hit proxies */
	uint32 HitProxySize;

	/** What is the current window mode. */
	EWindowMode::Type WindowMode;

	/** True if the viewport client requires hit proxy storage. */
	uint32 bRequiresHitProxyStorage : 1;