How to: First Person Mesh(Arms) to follow the crosshair

Development Programming & Scripting C++
1

Hi,

I’m trying to understand how the arms are following the crosshair movement in ShooterGame.

I want to implement the same functionality, but I can’t get where the value are set for the Arms.

I catch for the ThirdPerson mesh but can’t get it for the FirstPerson.

Thanks,

2

The crosshair in shootergame is drawn in the center of the screen.
The movement of the players view is controlled by adding pitch to the player controller.

3

This was not what I’m looking for. I wanted to know how the Arms were following the mouse movement.
And I found it, it’s in CameraUpdate on Character class.

thanks,

4

Could you explain the method you used in some detail?
That be awsome. :slight_smile:

5

Odd, I would like to know more too. I just made my own arms children of the Camera and everything worked fine :slight_smile:

6

Just look in ShooterGame code in the CharacterClass::OnCameraUpdate(const FVector& CameraLocation, const FRotator& CameraRotation)

They are using the camera location & rotation to place & rotate the arms correctly.



USkeletalMeshComponent* DefMesh1P = Cast<USkeletalMeshComponent>(GetClass()->GetDefaultSubobjectByName(TEXT("PawnMesh1P")));
	const FMatrix DefMeshLS = FRotationTranslationMatrix(DefMesh1P->RelativeRotation, DefMesh1P->RelativeLocation);
	const FMatrix LocalToWorld = ActorToWorld().ToMatrixWithScale();

	// Mesh rotating code expect uniform scale in LocalToWorld matrix

	const FRotator RotCameraPitch(CameraRotation.Pitch, 0.0f, 0.0f);
	const FRotator RotCameraYaw(0.0f, CameraRotation.Yaw, 0.0f);

	const FMatrix LeveledCameraLS = FRotationTranslationMatrix(RotCameraYaw, CameraLocation) * LocalToWorld.InverseSafe();
	const FMatrix PitchedCameraLS = FRotationMatrix(RotCameraPitch) * LeveledCameraLS;
	const FMatrix MeshRelativeToCamera = DefMeshLS * LeveledCameraLS.InverseSafe();
	const FMatrix PitchedMesh = MeshRelativeToCamera * PitchedCameraLS;

	Mesh1P->SetRelativeLocationAndRotation(PitchedMesh.GetOrigin(), PitchedMesh.Rotator());
7

Thanks i will have a look at the shooter example as well. :slight_smile:
Thanks for the share.

8

Also, if your weapon class contains your arms, and it is simply extended from actor, you can set the rotation from the Character’s tick function:



void MyCharacter::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
    
    Weapon->SetActorLocation(GetPawnViewLocation());
    Weapon->SetActorRotation(GetViewRotation());
}