I need help on my unity project. Camera is acting weird, I'm trying to move my player in the direction the camera is looking

Question

When I turn my player, my character doesn't move in the direction it's pointing. My movement script is:

using UnityEngine;

public class PlayerMovement : MonoBehaviour {

    [SerializeField] public Rigidbody rb;
    [SerializeField] public Rigidbody speed;

    // Update is called once per frame
    void FixedUpdate()
    {
        // These are the keys.
        if ( Input.GetKey("d") )
        {
            rb.AddForce(speed, 0, 0);
        }
        if ( Input.GetKey("a") )
        {
            rb.AddForce(-speed, 0, 0);
        }
        if ( Input.GetKey("w") )
        {
            rb.AddForce(0, 0, speed);
        }
        if ( Input.GetKey("s") )
        {
            rb.AddForce(0, 0, -speed);
        }
    }
}

My turning script for the camera and the character is:

using UnityEngine;

    public class CameraScript : MonoBehaviour
    {
        public Transform t;
        int m = 1;
        // Start is called before the first frame update
        void FixedUpdate()
        {
            if ( Input.GetKey("q"))
            {
                transform.Rotate(0,-m, 0 * Time.deltaTime);
            }
            if ( Input.GetKey("e"))
            {
                transform.Rotate(0,m,0 * Time.deltaTime);
            }
        }
    }

I have no error that I can tell you, sorry for the lack of info, I just don't know what's happening in my game.

Answer 1

In addition to Luemus' answer

First in

public Rigidbody speed;

I assume a typo and it most probably should be a

public float speed;

Then you seem to only rotate the camera but you never rotate t which seems to be your player object reference.

Anyway, in general whenever there is any Rigidbody and thereby the physics engine involved you shouldn't set any hard value via the Transform component - not even in FixedUpdate. This might break physics, collision detection and lead to strange behavior.

Rather go through the Rigidbody component like e.g.

public Rigidbody player;

// For the Camera which I assume be not part of the Rigidbody
// It is ok to rotate in Update
void Update()
{
    if (Input.GetKey(KeyCode.Q))
    {
        // You most likely would rather want to multiply "m" with "Time.deltaTime"
        // .. not "0"
        transform.Rotate(0,-m * Time.deltaTime, 0);
    }

    if ( Input.GetKey(KeyCode.E))
    {
        // Same here
        transform.Rotate(0,m * Time.deltaTime, 0);
    }
}

private void FixedUpdate()
{
    // Now tell the player Rigidbody to mirror the camera rotation
    player.MoveRotation(transform.rotation);
}

Answer 2

AddForce method uses world space!

Try using AddRelativeForce instead:

if ( Input.GetKey("d") )
{
    rb.AddRelativeForce(speed, 0, 0);
}
...

Note that AddRelativeForce will also take the scales into account.

Or alternatively take the rb.rotation into account:

if ( Input.GetKey("d") )
{
    rb.AddForce(rb.rotation * new Vector3(speed, 0, 0));
}
...