Rotate object's local up towards a vector.

This worked perfectly, thank you! I used the first option you posted. Is there anyway to do this over time so it doesn't pop to that rotation? Thanks!

You need to Lerp towards the direction:

Using the first method this might work:

     objectA.transform.up = Vector3.Lerp(objectA.transform.up, direction, Time.deltaTime * speedFactor);

I'd normally use the second method which would look like:

      var targetRotation = Quaternion.FromToRotation(Vector3.forward, Vector3.up) * Quaternion.LookRotation(direction);
      transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, Time.deltaTime * speedFactor);

$$anonymous$$ight also be worth trying the Slerp method, too.

In this case it would be hard to quantify the difference since it's using the "fudgy" smoothing of a Lerp towards a value using the time step - if you were to ensure that the smooth movement happened over a fixed period of time (perhaps by using a coroutine) then Slerp would provide an easing effect rather than a hard start stop.

Thank you for this. I have been using NGUI for years and have often wanted to point a UI element not along the z axis at something in the scene and this works great for that. Here is some code to have an arrow follow the edge of the screen and point at a target using UGUI.

 public Transform target;
         public Camera mainCamera;
         public Transform ship;
         Image arrow;
         
         void Start () {
             arrow = GetComponent<Image> ();
         }
     
         void Update () {
 //Check used to see if item is on screen
             Vector3 screenPos = mainCamera.WorldToViewportPoint (target.position);
 //Get Vector to target from ship
             Vector3 distance = ship.position - target.position;
 //Get left, right, up and down variance and use UI width and height to deter$$anonymous$$e position
             float leftRight = Vector3.Dot (distance.normalized, target.right);
             float upDown = Vector3.Dot (distance.normalized, target.up);
             leftRight = $$anonymous$$athf.Clamp(-leftRight*480, -375, 375);
             upDown = $$anonymous$$athf.Clamp(-upDown*800,-88, 215);
 //Assign position
             transform.localPosition = new Vector3 (leftRight ,upDown,transform.localPosition.z);
 //Look at target using the right arrow.  Invert the normalized vector because the arrow moves //around the screen area.
                 transform.right = -distance.normalized;
 
 //If target is on screen show it if now hide it
             if (screenPos.x > 0 && screenPos.x < 1 &&
                 screenPos.y > 0.2f && screenPos.y < 1) {
                 arrow.enabled = false;
             } else {
                 arrow.enabled = true;
             }
     
         }