# Smooth Rotation for the love of epic

Hello, I just want to smooth the rotation of the needle when its rotate, I think I’m missing something
here i can’t seems to find it. i know about lerp and timeline but i cloud not understand the how to get the rotation of the needle ( start - end ) to be in lerp ( A - B ).

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Hey @Abdalah.Salameh!

I would actually suggest a timeline here. Play from start as the input, when you open up the timeline (double click) add a Float value and make two keys with value of 0 and 1. For the 0 value key, place it at time 0 as well. Figure out how long you want the movement to take, and place the key with value of 1 at that time.

Go back out to the event graph, and on the float output of the timeline, plug that into a LERP as the alpha. (0 value = A, 1 value = B). For the A and B use “Old health %” as A and “New health %” as B.

And there you go! Let us know if you need any additional walking through!

Also, as a bonus, you can right click the keys in the Timeline to add curve to the value so it can move faster or slower as different times.

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(post deleted by author)

Thank you mate but “Old health %" “New health %" ??? i dont understand from where i can get these?

Thank you! but sorry this sound more complicated than timeline & lerp nods

Well, when the player takes damage, before applying the damage you get “Health / Max health” which will be a %. That’s your “Old Health” (A), so save that float.

Then, you have the player take the damage or healing.

Upon taking the damage or heal, you have a new health value. So you do “Health / Max Health” again. That’s your “New Health” (B).

At the end of the event, run the Timeline and LERP I talked about, with A being “Old Health” and B being “New Health”. The timeline will run it’s course changing from A to B values. That goes into the “Alpha” on the LERP (this creates the slide effect).

The output on the lerp goes to the “Set Relative Rotation” Y like you have above, attached to the “Update” output on the Timeline, but instead of setting it instantly it should change between point A (before getting hit/healed) and point B (after getting hit/healed) gradually- the speed of which is governed by your timeline’s final Key.

Timeline and interpolate, u could also use event tick instead of timeline if you think it’s worth it. I mean it’s real simple, you just finterp current needle rotation to the target needle rotation.