A 💩 tweening library for Unity - only made for the pun, don't actually use it.

Make sure you have using Coroutween; at the top of your script

After that, you have a few options for how to tween stuff. In the following examples I'll show how to change the FOV of a camera with each approach.

1. The easiest way is to use premade tweens like this:

camera.FieldOfViewTo (to: 25f, duration, EaseType.ElasticOut);

2. The next way lets you tween any supported value (int, float, Vector2/3/4, Quaternion, Color)

Coroutween.To (from: camera.fieldOfView, to: 25f, duration, EaseType.ElasticOut, x => camera.fieldOfView = x);

3. The final way gives you complete control by simply providing a callback with the tween's eased progress.

var from = camera.fieldOfView;
var to = 25f;
Coroutween.CreateInterpolater (duration, EaseType.ElasticOut, t => camera.fieldOfView = Mathf.LerpUnclamped (from, to, t));

All of these examples produce the same result:

Every tween method that has an EaseType will also have an overload with an EaseMethod which is a callback that lets you calculate your own easing. If, for example, you wanted to use an animation curve instead of a preset easing type, you could pass curve.Evaluate instead of some EaseType.

Here's small example of how you could use it:

public float duration = 1f;
public AnimationCurve positionCurve = new AnimationCurve ();

private void Update ()
{
    if (Input.GetKeyDown (KeyCode.Space))
        transform.PositionTo (transform.position + Vector3.up, duration, positionCurve.Evaluate);
}

If you are a little clever, you could even use tweens with physics

public Transform target;
public float duration = 1f;
public Rigidbody rb;

private Vector3 targetPosition;

private IEnumerator Start ()
{
    while (true)
    {
        yield return Coroutween.To (transform.position, target.position, duration, EaseType.ElasticOut, x => targetPosition = x);
    }
}

private void FixedUpdate ()
{
    rb.MovePosition (targetPosition);
}