ue4 line trace code

void ATankPlayerController::Tick(float DeltaSeconds)
{
    Super::Tick(DeltaSeconds);

    if(LineTraceTankAim()) UE_LOG(LogTemp, Warning, TEXT("line good"));
}

bool ATankPlayerController::LineTraceTankAim() const
{
    auto AimDirection = FVector(0.0f);
    GetAimDirection(AimDirection);

    //get start and end of trace line
    auto CamPos = GetAutoActivateCameraForPlayer()->GetActorLocation(); //start
    auto TraceEnd = CamPos + AimDirection*ShootRange;                   //end

    FHitResult HitResult; //output
    return GetWorld()->LineTraceSingleByChannel
        (
            HitResult,
            CamPos, TraceEnd,
            ECollisionChannel::ECC_Visibility,
            FCollisionQueryParams::DefaultQueryParam,
            FCollisionResponseParams::DefaultResponseParam
        );
}

bool ATankPlayerController::GetAimDirection(FVector& OutAimDirection) const
{
    //get rasterized crosshair coordinates
    int32 cx,cy;
    GetViewportSize(cx, cy);
    float cfx = cx * CrosshairX;
    float cfy = cy * CrosshairY;
    FVector wl;                                                           //wl is garbage
    return DeprojectScreenPositionToWorld(cfx,cfy, wl, OutAimDirection);  //got AimDirection
}