Wheel rotation, what am I doing wrong?

Questions & Answers
1

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

2

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);
    }
}
3

Marvellous! Thanks so much for posting this!
This is the solution I was looking for, for a similar in principle but not in execution problem.
I’m glad you took the time to write this out!