# How can i check when Lerp has finished?

private bool hitted = false;
private Vector3 hitPosition;

private void Test()
{
RaycastHit hit;

if (Physics.Raycast(start.position, Vector3.left, out hit, 1.5f)
|| Physics.Raycast(start.position, Vector3.right, out hit, 1.5f)
|| Physics.Raycast(start.position, Vector3.forward, out hit, 1.5f))
{
if (hit.transform.tag == "Test")
{
hitted = true;
hitPosition = hit.transform.localPosition;
}
}
}

private void Update()
{
if (hitted == true)
{
player.localRotation = Quaternion.Lerp(player.localRotation, Quaternion.LookRotation(hitPosition), 1 * Time.deltaTime);
}
}


What i want to detect is when the player finished rotating and then set back hitted to false.

• The particular form of Lerp you've used here is an exponential ease-out - that means, mathematically, it never really "finishes" - it just gets closer and closer and closer to the target, slowing down as it goes. So, you can either test when the rotation has gotten "close enough," or switch to a form that completes the rotation in some fixed amount of time. What works better for your use case? Dec 3, 2017 at 0:25

## 2 Answers

You can check when your rotation has gotten "close enough" using a quaternion dot product, like so:

private void Update()
{
if (hitted == true)
{
Quaternion targetRotation = Quaternion.LookRotation(hitDirection);

// Ensure we're correctly compensating for variable framerate
float sharpness = 0.1f;
float blend = 1f - Mathf.Pow(1f - sharpness, 30f * Time.deltaTime);

player.localRotation = Quaternion.Lerp(player.localRotation, targetRotation, blend);

// A Quaternion dot product gives you the cosine of the angle
// between the rotations. Closer to 1 = more similar.
if(Quaternion.Dot(transform.rotation, targetRotation) > 0.9999f) {
// Now we're within 1 degree of the target rotation.
// Put your "arrived" code here.
}
}
}


Or, if you don't need to precisely control the exact threshold you want to use, Unity's default == operator on quaternions includes a little wiggle room, so in many cases you can even just test:

if (player.localRotatiin == targetRotation)


You can just use the t Time. Instead of writing 1 * Time.deltaTime just make 4 fields, LerpTime, CurrentLerpingTime, Speed, T;

Then check whether the T is more than or equal to 1, if it is then the lerp has finished!.

private float LerpTime = 1.0f;
private float CurrentLerpingTime;
private float Speed = 25f;

private void Update(){

......

if(hitted == true){

CurrentLerpingTime = Mathf.Clamp01(CurrentLerpingTime + (speed * Time.deltaTime));

t = CurrentLerpingTime / LerpTime;

player.localRotation = Quaternion.Lerp(player.localRotation, Quaternion.LookRotation(hitPosition), t);

if(t >= 1){
Debug.Log("Lerping Has Finished!");
}
}
}