VRPawnMovement.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/FloatingPawnMovement.h"
#include "Components/CapsuleComponent.h"
#include "Camera/CameraComponent.h"

#include "VRPawnMovement.generated.h"

/*
 * This Movement component is needed since in VR not only the pawn itself (UpdatedComponent) is moved but also the
 * user herself can walk and thereby move the CameraComponent, which can also lead to collisions or e.g. going up steps 
 *
 * The four modes are:
 * None: No controller movement is applied and no corrections regarding steps or collisions with walls are done
 * Ghost: The same as above but now the Inputs can be used for unconstrained flying (also through objects)
 * Fly: The user can fly but not through walls etc. When the user walks against a wall the scene is moved with her to avoid walking through
 *      The user can also walk up stairs with a maximum step height of MaxStepHeight
 * Walk: Additionally to Fly now gravity keeps the user on the floor
 */

UENUM(BlueprintType)
enum class EVRNavigationModes : uint8
{
	NAV_NONE UMETA(DisplayName = "None (no controller movement)"),
	NAV_GHOST UMETA(DisplayName = "Ghost (flying, also through walls)"),
	NAV_FLY UMETA(DisplayName = "Fly (prohibiting collisions)"),
	NAV_WALK UMETA(DisplayName = "Walk (gravity and prohibiting collisions)")
};

UCLASS()
class RWTHVRTOOLKIT_API UVRPawnMovement : public UFloatingPawnMovement
{
	GENERATED_UCLASS_BODY()

public:

	virtual void TickComponent(float DeltaTime, enum ELevelTick TickType,
	                           FActorComponentTickFunction* ThisTickFunction) override;

	void SetHeadComponent(USceneComponent* NewHeadComponent);

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "VR Movement")
	EVRNavigationModes NavigationMode = EVRNavigationModes::NAV_WALK;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "VR Movement")
	float MaxStepHeight = 40.0f;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "VR Movement")
	float GravityAcceleration = 981.0f;
	
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "VR Movement")
	float UpSteppingAcceleration = 500.0f;

	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "VR Movement")
	float CapsuleRadius = 40.0f;

private:
	FHitResult CreateLineTrace(FVector Direction, const FVector Start, bool Visibility);
	FHitResult CreateMultiLineTrace(FVector Direction, const FVector Start, float Radius, bool Visibility);
	void SetCapsuleColliderToUserSize();
	void CheckForPhysWalkingCollision();
	bool CheckForVirtualMovCollision(FVector PositionChange, float DeltaTime);
	void MoveByGravityOrStepUp(float DeltaSeconds);
	void ShiftVertically(float DiffernceDistance, float VerticalAcceleration, float DeltaSeconds, int Direction);
	//(direction = Down = -1), (direction = Up = 1)

	UPROPERTY(VisibleAnywhere) UCapsuleComponent* CapsuleColliderComponent = nullptr;
	UPROPERTY() USceneComponent* HeadComponent = nullptr;

	float VerticalSpeed = 0.0f;
	FVector LastHeadPosition;
};