Adding BasicVRInteractionComponent to encapsulate clicking and grabbing behavior

Source/DisplayClusterExtensions/Private/BasicVRInteractionComponent.cpp

+// Fill out your copyright notice in the Description page of Project Settings.
+
+
+#include "BasicVRInteractionComponent.h"
+
+
+#include "Clickable.h"
+#include "Grabable.h"
+#include "GrabbingBehaviorComponent.h"
+
+// Sets default values for this component's properties
+UBasicVRInteractionComponent::UBasicVRInteractionComponent()
+{
+	// 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;
+
+	// ...
+}
+
+void UBasicVRInteractionComponent::BeginInteraction()
+{
+	if(!InteractionRayEmitter) return;
+	
+	// start and end point for raytracing
+	const FTwoVectors StartEnd = GetHandRay(MaxClickDistance);
+	const FVector Start = StartEnd.v1;
+	const FVector End   = StartEnd.v2;	
+
+	// will be filled by the Line Trace Function
+	FHitResult Hit;
+
+	//if hit was not found return  
+	const FCollisionObjectQueryParams Params;
+	if (!GetWorld()->LineTraceSingleByObjectType(Hit, Start, End, Params))
+		return;
+
+	AActor* HitActor = Hit.GetActor();
+	
+	// try to cast HitActor int a Grabable if not succeeded will become a nullptr
+	IGrabable*  GrabableActor  = Cast<IGrabable>(HitActor);
+	IClickable* ClickableActor = Cast<IClickable>(HitActor);
+
+	if (GrabableActor != nullptr && Hit.Distance < MaxGrabDistance)
+	{
+		// call grabable actors function so he reacts to our grab
+		GrabableActor->OnGrabbed_Implementation();
+		
+
+		UGrabbingBehaviorComponent* Behavior = HitActor->FindComponentByClass<UGrabbingBehaviorComponent>();
+		if ( Behavior == nullptr)
+			HandlePhysicsAndAttachActor(HitActor);
+
+		// we save the grabbedActor in a general form to access all of AActors functions easily later
+		GrabbedActor = HitActor;
+	}
+	else if (ClickableActor != nullptr && Hit.Distance < MaxClickDistance)
+	{
+		ClickableActor->OnClicked_Implementation(Hit.Location);
+	}
+}
+
+
+void UBasicVRInteractionComponent::EndInteraction()
+{
+	if(!InteractionRayEmitter) return;
+	
+	// if we didnt grab anyone there is no need to release
+	if (GrabbedActor == nullptr)
+		return;
+
+	// let the grabbed object reacot to release
+	Cast<IGrabable>(GrabbedActor)->OnReleased_Implementation();
+
+	// Detach the Actor
+
+	UPrimitiveComponent* PhysicsComp = GrabbedActor->FindComponentByClass<UPrimitiveComponent>();
+	UGrabbingBehaviorComponent* Behavior = GrabbedActor->FindComponentByClass<UGrabbingBehaviorComponent>();
+	if (Behavior == nullptr)
+	{
+		GrabbedActor->GetRootComponent()->DetachFromComponent(FDetachmentTransformRules::KeepWorldTransform);
+		PhysicsComp->SetSimulatePhysics(bDidSimulatePhysics);
+	}
+
+	// forget about the actor
+	GrabbedActor = nullptr;
+}
+
+// Called every frame
+void UBasicVRInteractionComponent::TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
+{
+	Super::TickComponent(DeltaTime, TickType, ThisTickFunction);
+
+	// if an actor is grabbed and a behavior is defined move move him accordingly  
+	if (GrabbedActor == nullptr || 	InteractionRayEmitter == nullptr) return;
+	
+	UGrabbingBehaviorComponent* Behavior = GrabbedActor->FindComponentByClass<UGrabbingBehaviorComponent>();
+
+	// if our Grabable Actor is not constrained
+	if (Behavior != nullptr)
+	{	
+		// specifies the hand in space
+		const FVector HandPos = InteractionRayEmitter->GetComponentLocation();
+		const FQuat HandQuat = InteractionRayEmitter->GetComponentQuat();
+
+		Behavior->HandleNewPositionAndDirection(HandPos, HandQuat); 
+	}
+}
+
+void UBasicVRInteractionComponent::Initialize(USceneComponent* RayEmitter, float InMaxGrabDistance, float InMaxClickDistance)
+{
+	if(RayEmitter != nullptr) return;
+
+	InteractionRayEmitter = RayEmitter;
+	MaxGrabDistance = InMaxGrabDistance;
+	MaxClickDistance = InMaxClickDistance;
+}
+
+void UBasicVRInteractionComponent::HandlePhysicsAndAttachActor(AActor* HitActor)
+{
+	UPrimitiveComponent* PhysicsComp = HitActor->FindComponentByClass<UPrimitiveComponent>();	
+	
+	bDidSimulatePhysics = PhysicsComp->IsSimulatingPhysics(); // remember if we need to tun physics back on or not	
+	PhysicsComp->SetSimulatePhysics(false);
+	FAttachmentTransformRules Rules = FAttachmentTransformRules(EAttachmentRule::KeepWorld, true);
+	HitActor->AttachToComponent(InteractionRayEmitter, Rules);
+}
+
+FTwoVectors UBasicVRInteractionComponent::GetHandRay(const float Length) const
+{
+	const FVector Start = InteractionRayEmitter->GetComponentLocation();
+	const FVector Direction = InteractionRayEmitter->GetForwardVector();
+	const FVector End = Start + Length * Direction;
+
+	return FTwoVectors(Start, End);
+}

Source/DisplayClusterExtensions/Public/BasicVRInteractionComponent.h

+// Fill out your copyright notice in the Description page of Project Settings.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Components/ActorComponent.h"
+#include "BasicVRInteractionComponent.generated.h"
+
+
+UCLASS( ClassGroup=(Custom), meta=(BlueprintSpawnableComponent) )
+class DISPLAYCLUSTEREXTENSIONS_API UBasicVRInteractionComponent : public UActorComponent
+{
+	GENERATED_BODY()
+
+public:	
+	// Sets default values for this component's properties
+	UBasicVRInteractionComponent();
+
+	UFUNCTION(BlueprintCallable) void BeginInteraction(); 
+	UFUNCTION(BlueprintCallable) void EndInteraction();   	
+	
+	// Called every frame
+	virtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;
+
+	UPROPERTY(BlueprintReadWrite) float MaxGrabDistance = 50;
+	UPROPERTY(BlueprintReadWrite) float MaxClickDistance = 500;
+
+	UFUNCTION(BlueprintCallable) void Initialize(USceneComponent* RayEmitter, float InMaxGrabDistance = 50, float InMaxClickDistance = 500);
+	
+	UFUNCTION(BlueprintCallable, BlueprintPure) AActor* GetGrabbedActor() const { return GrabbedActor;	}
+	UFUNCTION(BlueprintCallable, BlueprintPure) USceneComponent* GetInteractionRayEmitter() const { return InteractionRayEmitter;	}
+private:
+	/* indicates if the grabbed actor was simulating physics before we grabbed it */
+	UPROPERTY() bool bDidSimulatePhysics;	
+	/* Holding a reference to the actor that is currently being grabbed */
+	UPROPERTY() AActor* GrabbedActor;
+	UPROPERTY() USceneComponent* InteractionRayEmitter = nullptr;
+	
+	void HandlePhysicsAndAttachActor(AActor* HitActor);
+	FTwoVectors GetHandRay(float Length) const;
+};