Small performance improvements

Unreal Courses Talk
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#1

Hi, great tutorials so far.

I would like to share some small performance improvements to the solution provided.

  • There is no need to recalculate JourneyLength on every tick. It is always the same value so we can create a member variable to store it.

  • Actually, we don’t even need to calculate the distance between the two locations using the Size function. We can use the DistSquared function from FVector which is faster as it does not calculate a square root and we just need to compare distances, so we are good.

  • There is no need either to obtain the Direction vector on every tick. We can store it at BeginPlay and invert it every time we reach the target location.

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

    if (HasAuthority())
    {
        FVector CurrentLocation = GetActorLocation();

        // Check if we have reached the target.
        if (FVector::DistSquared(GlobalStartLocation, CurrentLocation) >= SquareDistance)
        {
            // Swap the target and start locations.
            Swap(GlobalStartLocation, GlobalTargetLocation);

            // Invert the movement direction.
            MovementDirection *= -1;
        }
        else
        {
            // Keep moving towards the target.
            SetActorLocation(CurrentLocation + (MovementDirection * Speed * DeltaSeconds));
        }
    }
}

void AMovingPlatform::BeginPlay()
{
    Super::BeginPlay();
    
    if (HasAuthority())
    {
        SetReplicates(true);
        SetReplicateMovement(true);

        GlobalStartLocation = GetActorLocation();

        // We need to transform the LOCAL TargetLocation to Global space.
        GlobalTargetLocation = GetTransform().TransformPosition(TargetLocation);

        MovementDirection = (GlobalTargetLocation - GlobalStartLocation).GetSafeNormal();

        SquareDistance = FVector::DistSquared(GlobalTargetLocation, GlobalStartLocation);
    }
}

It would be also possible to calculate the time that will take to reach the target position at the BeginPlay and work with that… Can anyone think about any cons about that last approach?

Thanks!

4 Likes
#2

I know this post was a while ago but: the only concern about using time is if the game is paused you would also have to account for this in the time to reach the location.

#3

True. Its all about the context. That’s different for every project really.

Always something different assuming its not copy paste or only using the exact same thing without differences.

What works for one might not work for another.

#4

In the context of multiplayer, other players don’t pause when you do. So, allowing things to continue in the background is a perfectly valid approach.
Single player is a whole different story.

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