The best navigation code to using rigidbody in unity3d?

Question

I want to press the key once

My cube moves to the right and rotates 90 degrees

The rotation is well done

But it does not move well

using UnityEngine;

using System.Collections;

public class Player : MonoBehaviour
{

    public float speed;

    public float time;

    public GameObject contactPoint;

    private Rigidbody rig;

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

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.D))
        {
            StartCoroutine(RotatePlayer(Vector3.forward * 90, Vector3.right, time));
        }

        if (Input.GetKeyDown(KeyCode.A))
        {
            StartCoroutine(RotatePlayer(Vector3.back * 90, Vector3.left, time));
        }
    }

    private IEnumerator RotatePlayer(Vector3 byAngle, Vector3 dir, float inTime)
    {

        Quaternion fromAngle = contactPoint.transform.rotation;
        Quaternion toAngle = Quaternion.Euler(transform.eulerAngles - byAngle);

        for (float t = 0; t < 1; t += Time.deltaTime / inTime)
        {   
            rig.MovePosition(transform.position + (dir * speed * Time.deltaTime));
            rig.MoveRotation(Quaternion.Slerp(fromAngle, toAngle, t));

            yield return null;
        }
    }
}

Answer 1

Your main issue is: You should do Physics related things like movement of a Rigidbody only in FixedUpdate.

For Coroutines Unity provides WaitForFixedUpdate which does exactly what the name says, making sure the code after it is executed in a FixedUpdate physics call.

private IEnumerator RotatePlayer(Vector3 byAngle, Vector3 dir, float inTime)
{
    yield return new WaitForFixedUpdate();

    // here I would also use "rig" instead of "transform"
    Quaternion fromAngle = contactPoint.transform.rotation;
    Quaternion toAngle = Quaternion.Euler(rig.eulerAngles - byAngle);

    for (float t = 0; t < 1; t += Time.deltaTime / inTime)
    {   
        yield return new WaitForFixedUpdate();

        // here I would also use "rig" instead of "transform"
        rig.MovePosition(rig.position + (dir * speed * Time.deltaTime));
        rig.MoveRotation(Quaternion.Slerp(fromAngle, toAngle, t));
    }
}

beyond that it is a bit unclear what exactly you define as not move well. You also should somehow make sure that only one routine is running at a time. Either by terminating already running routines like

private void Update()
{
    if (Input.GetKeyDown(KeyCode.D))
    {
        StopAllCoroutines();
        StartCoroutine(RotatePlayer(Vector3.forward * 90, Vector3.right, time));
    }

    if (Input.GetKeyDown(KeyCode.A))
    {
        StopAllCoroutines();
        StartCoroutine(RotatePlayer(Vector3.back * 90, Vector3.left, time));
    }
}

or preventing new routines from starting until the current one is finished using a flag like

private bool alreadyRotating;

private IEnumerator RotatePlayer(Vector3 byAngle, Vector3 dir, float inTime)
{
    if(alreadyRotating) yield break;

    alreadyRotating = true;

    ......

    alreadyRotating = false;
}