Install

Add to your Unity project as a git package using the package manager.

https://github.com/Less3Design/L3-tween.git

Usage

L3 Tween is based around exclusively supporting the way I like to write tweens:

private Tween moveTween;

void DoAnimation()
{
    Vector3 startPos = transform.position;
    Vector3 endPos = Random.insideUnitSphere;
    //cancel previous tween, start a new one
    moveTween = moveTween.Cancel().New(1f).SetOnUpdate((t) => {
      transform.position = Vector3.Lerp(startPos,endPos,t);
    });
}

Tween is a readonly struct handle, so always assign the result of Cancel() / New(). A handle goes dead the moment its tween completes or is cancelled; tween.IsActive tells you which. Setting a callback on a dead handle logs a warning and does nothing.

Supporting just a single use case lets us keep the business logic to only a couple hundred lines. Here is all the state we mainatin:

public class TweenObject
{
    public ushort id;
    public ushort version;
    public bool active;
    public int activeIndex;

    public float fromValue;
    public float toValue;
    public float duration;
    public float elapsedTime;
    public Ease easeType;
    public TweenUpdateType deltaTimeType;

    public Action<float> onUpdate;
    public Action onComplete;
    public Action onCancel;
}

Pool size

The pool starts at 512 tweens and doubles whenever it runs out, up to a max of 4096 (hard limit 65536, ids are ushorts).

Configure it from Project Settings > Less3 > Tween or from code, before the first tween:

[RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
static void ConfigureTweens() => TweenManager.Configure(initialPoolSize: 1024, maxPoolSize: 8192);

Performance

It's super good enough. If you need to animate many thousands of objects at once I reccomend treating that like a particle system, don't use tweens.

• TweenObjects are pooled; allocation is O(1) off a free list
• Only active tweens are iterated. A frame with no tweens running costs a single int compare
• The biggest cost will be whatever you allocate and execute inside tweens
• No async job burst etc... because the goal is to keep code as simple as possible

Video showing the system allocating tweens through its pool

Recording.2025-12-20.170935.mp4