Rotation third person in direction to camera?

Question

I want my object to rotate towards the camera at the same time when I rotate the camera, so that the player while walking is always oriented in the direction of the camera, as in typical third-person games. Unfortunately, any method used so far leads me to a rotation of the object, slightly behind, the rotation of the camera. I've been looking for a solution for a week and I'm desperate. I publish a video of the rotation I have with an object.

video of the late rotation

private Rigidbody rb;
public float speed = 1.0f;

void Start()
    {
      rb = GetComponent<Rigidbody>(); 
    }

direction = Camera.main.transform.forward;
direction.y = 0.00f;

private void FixedUpdate ()
{

 Quaternion targetRotation = Quaternion.LookRotation(direction);
Quaternion newRotation = Quaternion.Lerp(rb.transform.rotation, targetRotation, speed * Time.fixedDeltaTime);
rb.MoveRotation(newRotation);
 }  

}

Answer 1

This is an inappropriate use for Quaternion.Lerp because you aren't working with a proportion of how far to move. Currently, you're basically telling it to only rotate a tiny percentage of the way to the target rotation.

You should rather use Quaternion.RotateTowards, because you can easily calculate angular rotation based on deltaTime (or, fixedDeltaTime as you use):

public float speed = 30f; // max rotation speed of 30 degrees per second

// ...

Quaternion newRotation = Quaternion.RotateTowards(rb.transform.rotation, targetRotation, 
        speed * Time.deltaTime);
rb.MoveRotation(newRotation);

After re-reading your question, now it seems that you don't want a smooth transition/lerp. In that case, just set the rotation to the target rotation:

rb.MoveRotation(targetRotation);

If even that is too much interpolation/not immediate enough, you could set the rigidbody's rotation in Update:

private void Update ()
{
    rb.rotation = Quaternion.LookRotation(direction);
}