A smooth (ease in out) version of Lerp?

Hi there,
I was using some code like this to move a camera from one position to another, but I can't figure out a way to get it to ease out and in of the movement. I realise that Lerp is Linear, but is there a way to get it to be smooth?

I've looked into mathfx but im not sure how to use the hermite function with this code...

Code (csharp):

1.  
2. var Startspot : Transform;
3. var Midspot : Transform;
4. var Endspot : Transform;
5.  
6. function Update () {
7. transform.position = Vector3.Lerp(Startspot.position,Endspot.position,Time.time);
8. }

Thanks
Pete

 

Well, you could replace Time.time with a variable of your own and smooth it by hand.... 1 = at the other side, 0 = at the first side.

 

Something like this should work:

Code (csharp):

1.  
2. var time = Mathfx.Hermite(0.0, 1.0, Time.time);
3. transform.position = Vector3.Lerp(Startspot.position,Endspot.position,time);

 

The easiest thing is, don't use Update, use coroutines. Mathf.Smoothstep is useful too:

Code (csharp):

1. var startspot : Transform;
2. var endspot : Transform;
3.  
4. function Start () {
5.     SmoothMove(startspot.position, endspot.position, 5.0);
6. }
7.  
8. function SmoothMove (startpos : Vector3, endpos : Vector3, seconds : float) {
9.     var t = 0.0;
10.     while (t <= 1.0) {
11.         t += Time.deltaTime/seconds;
12.         transform.position = Vector3.Lerp(startpos, endpos, Mathf.SmoothStep(0.0, 1.0, t));
13.         yield;
14.     }
15. }

--Eric

 

you could use easingfunctions like this:

Code (csharp):

1.  
2. void Update()
3. {
4.     if (Time.time - timeStamp <= duration)
5.         factor = (float)Cubic.easeInOut(Time.time - timeStamp, 0, 1, duration);
6. }
7.  
8.  
9. void FixedUpdate()
10. {
11.     Vector3 changePosition = startPosition + factor * (targetPosition - startPosition);
12.     transform.localPosition = changePosition;
13. }
14.  

 

Hey thanks Guys!
I ended up using Eric5h5's solution as it fitted best with what I was doing.
That works great but I was wondering, is there a way to exaggerate the easing effect there?
Thanks again!
Pete

 

Apply the smoothstep to itself again...maybe kind of cheesy, but should be effective:

Code (csharp):

1. transform.position = Vector3.Lerp(startpos, endpos, Mathf.SmoothStep(0.0, 1.0, Mathf.SmoothStep(0.0, 1.0, t)));

--Eric

 

That worked perfect,
I actually triple embedded it! 0_o
Thanks again.

 

You could just use Sine of Time. Know how the Sine wave looks smooth? That's an ease-in out function. This is what I use:

Code (CSharp):

1.  
2. float t =0;
3. float duration = 2f;
4. Transform from;
5. Transform to;
6. float moveSpeed = 0f;
7. void Start(){
8.         transform.position = from.position;
9.         moveSpeed = Vector3.Distance(from.position, to.position);
10. }
11. void Update(){
12.  
13.     t += Time.deltaTime;
14.     if (t < duration){
15.         transform.position += -transform.up * Time.deltaTime * Mathf.Sin(t * Mathf.PI / duration) * moveSpeed/Mathf.PI * 2f;
16.     }
17. }

 

If you want to be able to fine tune your interpolation function, you can use an AnimationCurve so you can edit the curve manually from the Inspector:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class CustomInterpolation : MonoBehaviour
5. {
6.     public AnimationCurve curve = AnimationCurve.Linear(0.0f, 0.0f, 1.0f, 1.0f);
7.     public Transform start;
8.     public Transform end;
9.     public float duration = 1.0f;
10.     float t;
11.     // Use this for initialization
12.     void Start ()
13.     {
14.         t = 0.0f;
15.     }
16.  
17.     // Update is called once per frame
18.     void Update ()
19.     {
20.         t += Time.deltaTime;
21.         float s = t / duration;
22.         transform.position = Vector3.Lerp(start.position, end.position, curve.Evaluate(s));
23.     }
24. }
25.  

Doing the tweening yourself can be tedious, I suggest using an external tool. I'm really satisfied with DOTween:

http://dotween.demigiant.com/

It will make you code simpler and save you a lot of time:

Code (CSharp):

1. using UnityEngine;
2. using DG.Tweening;
3.  
4. public class CustomInterpolation : MonoBehaviour
5. {
6.     public AnimationCurve curve = AnimationCurve.Linear(0.0f, 0.0f, 1.0f, 1.0f);
7.     public Transform start;
8.     public Transform end;
9.     public float duration = 1.0f;
10.  
11.     // Use this for initialization
12.     void Start ()
13.     {
14.         transform.DOMove(end.position, duration)
15.             .ChangeStartValue(start.position)
16.             .SetEase(curve);
17.     }
18. }
19.  

 

Thought I would share my move and rotate coroutine based on ericbegue's code above. Thanks for the share!

Code (CSharp):

1.    
2.     public Transform m_playerTrans;
3.     public AnimationCurve m_moveCurve = AnimationCurve.Linear(0.0f, 0.0f, 1.0f, 1.0f);
4.     public float m_moveDuration = 1.0f;
5.  
6.     void DoMove()
7.     {
8.         StartCoroutine(MoveToPosition(m_playerTransform, destinationTransform, m_moveDuration));
9.     }
10.  
11.     private IEnumerator MoveToPosition(Transform movingTrans, Transform moveToTrans, float duration)
12.     {
13.         float animationTime = 0;
14.         var startPos = movingTrans.position;
15.         var startRot = movingTrans.rotation;
16.         var endPos = moveToTrans.position;
17.         var endRot = moveToTrans.rotation;
18.         var animationTimeLength = m_moveCurve[m_moveCurve.length - 1].time;
19.  
20.         while(animationTime < animationTimeLength)
21.         {
22.             animationTime += (Time.deltaTime / duration);
23.             movingTrans.position = Vector3.Lerp(startPos, endPos, m_moveCurve.Evaluate(animationTime));
24.             movingTrans.rotation = Quaternion.Slerp(startRot, endRot, m_moveCurve.Evaluate(animationTime));
25.             yield return null;
26.         }
27.     }

 

take your t value and pass it through one of these first.
https://gist.github.com/Fonserbc/3d31a25e87fdaa541ddf

 

Holy crap this helped me so much, being able to visually play with the curves in the inspector was a huge help for what I'm currently working on. Thanks!

 

@ericbegue Love ya !!!

As an artist, there's only so much nested calculations my brain can handle before it explodes.

Your solution with Dotween and animation Curves is brilliant!

Thanks alot