feat(pawn): Adds VR scaling functionality

Source/RWTHVRToolkit/Private/Pawn/RWTHVRPawn.cpp

@@ -41,8 +41,30 @@ ARWTHVRPawn::ARWTHVRPawn(const FObjectInitializer& ObjectInitializer) : Super(Ob
 
 	LeftHand = CreateDefaultSubobject<UReplicatedMotionControllerComponent>(TEXT("Left Hand MCC"));
 	LeftHand->SetupAttachment(RootComponent);
+
+	GetRootComponent()->TransformUpdated.AddLambda([this](USceneComponent*, EUpdateTransformFlags, ETeleportType)
+	{
+		FVector CurrentScale = this->GetActorScale3D();
+		if (CurrentScale.X == CurrentScale.Y && CurrentScale.Y == CurrentScale.Z)
+		{
+			float expectedScale = GetWorldSettings()->WorldToMeters / InitialWorldToMeters;
+			float ErrorPrecision = 1E-05;
+			if (FMath::IsNearlyEqual(CurrentScale.X, expectedScale, ErrorPrecision))
+			{
+				return;
+			}
+		}
+		UE_LOGFMT(Toolkit, Warning,
+		          "ARWTHVRPawn: Do not adjust the scale of the pawn directly. This will not work in VR. Use ARWTHVRPawn::SetScale(float) instead.")
+		;
+	});
+}
+
+void ARWTHVRPawn::BeginPlay()
+{
+	Super::BeginPlay();
+	InitialWorldToMeters = GetWorldSettings()->WorldToMeters;
 }
-void ARWTHVRPawn::BeginPlay() { Super::BeginPlay(); }
 
 void ARWTHVRPawn::Tick(float DeltaSeconds)
 {
@@ -56,6 +78,17 @@ void ARWTHVRPawn::Tick(float DeltaSeconds)
 	EvaluateLivelink();
 }
 
+/*
+ *	Scales the Pawn while also adjusting the WorldToMeters ratio to adjust for pupillary distance.
+ *	Only supports uniform scaling.
+ */
+void ARWTHVRPawn::SetScale(float NewScale)
+{
+	FVector NewScaleVector = FVector(NewScale, NewScale, NewScale);
+	GetWorldSettings()->WorldToMeters = InitialWorldToMeters * NewScale;
+	SetActorScale3D(NewScaleVector);
+}
+
 /*
  * The alternative would be to do this only on the server on possess and check for player state/type,
  * as connections now send their playertype over.

Source/RWTHVRToolkit/Public/Pawn/RWTHVRPawn.h

@@ -31,6 +31,9 @@ public:
 
 	virtual void NotifyControllerChanged() override;
 
+	UFUNCTION(BlueprintCallable)
+	void SetScale(float NewScale);
+	
 	UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Pawn|Input")
 	TArray<UInputMappingContext*> InputMappingContexts;
 
@@ -111,4 +114,5 @@ protected:
 
 private:
 	UInputComponent* ActivePlayerInputComponent;
+	float InitialWorldToMeters;
 };