Wheel rotation, what am I doing wrong?

Question

Ok so I am trying to get a wheel to rotate an object as if it is a wheel of a known diameter and traveling a known distance, and I need to know how much to rotate the object.

My understanding is the equation for that is ( distance / circumference = degrees to rotate ), where circumference = diameter * pi. Except when I try to actually apply that equation the rotations I am getting are tiny compared to the movement.

 public class WheelDebug : MonoBehaviour
 {
     public float MoveSpeed = 1;
     public float Diamiter = 1.41f;
     
     // Update is called once per frame
     void Update()
     {
         float distanceMoved = MoveSpeed * Time.deltaTime;
         transform.position += Vector3.forward * distanceMoved;
 
         float circumference = Diamiter * Mathf.PI;
         float rotationToTravelDistance = distanceMoved / circumference;
         transform.rotation *= Quaternion.Euler(rotationToTravelDistance, 0, 0);
     }
 }

So based on my understanding, what is happening above is every frame, which occurs ~60 times a second, my object moves MoveSpeed * Time.deltaTime, resulting in the object moving 1 unity unit or meter, per second in game, regardless of framerate.

Since I record it as distanceMoved, I can then plug that into the wheel turn calculation since I know that is the exact distance the object moved this frame, and.... I know what I did wrong.

Posting this anyway so anyone running into the same problem

Answer 1

Best Answer

Answer by CiberX15 · Jul 27, 2021 at 01:18 AM

Ok so the problem was my equation was correctly returning the PERCENTAGE of how far I needed to turn, it wasn't returning the degrees of rotation. So all I had to do to make it work seamlessly is multiply the rotation travel distance by 360. So the corrected code is as follows:

 public class WheelDebug : MonoBehaviour
 {
     public float MoveSpeed = 1;
     public float Diamiter = 1.41f;
     
     // Update is called once per frame
     void Update()
     {
         float distanceMoved = MoveSpeed * Time.deltaTime;
         transform.position += Vector3.forward * distanceMoved;
 
         float circumference = Diamiter * Mathf.PI;
         float rotationToTravelDistance = distanceMoved / circumference;
         transform.rotation *= Quaternion.Euler(rotationToTravelDistance * 360, 0, 0);
     }
 }

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elenzil · Jul 27, 2021 at 06:27 PM 0

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glad you sorted it.

ps, 360 degrees in a circle, 365 days in a year.

CiberX15 elenzil · Jul 28, 2021 at 02:57 AM 0

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[face palms] Fixed.

Wheel rotation, what am I doing wrong?

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