Unity player movement, rotation breaks the movement

Question

I'm new on unity and I developed a script to move a player cube:

        var moveSpeed = 5.0f;

        var x = moveSpeed * Input.GetAxis("Horizontal") * Time.deltaTime;
        var z = moveSpeed * Input.GetAxis("Vertical") * Time.deltaTime;

        transform.Translate(
            x,
            0f,
            z
        );

This works fine, the cube moves around the plane.

Then I wanted to make the cube rotate to face the movement, I mean, if the cube is moving to the right, face the right, etc.

the problem is when I change the transform.rotation with the direction position, there is a strange behaviour.

The movement is like WASD (the camera doesn't rotate, but I want to use Input.GetAxis("Horizontal"))

Any idea?

Thanks

Answer 1

void Update()
{
    var moveSpeed = 5.0f;

    //move relative to world space (so rotation doesn't affect movement)
    var x = moveSpeed * Input.GetAxis("Horizontal") * Time.deltaTime;
    var z = moveSpeed * Input.GetAxis("Vertical") * Time.deltaTime;
    transform.Translate(x, 0f, z, Space.World);

    //work out angle using atan 2
    float angle = Mathf.Atan2(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical")) * Mathf.Rad2Deg;

    // prevent cube snapping to angle if there is no movement
    if(Input.GetAxis("Horizontal") != 0f || Input.GetAxis("Vertical") != 0f)
        transform.rotation =  Quaternion.Euler(0f, angle, 0f);
}

Atan2 is used to work out the rotation as it will take XY values and generate an angle in radians. So all we have to do is convert the radians to degrees via angle * Mathf.Rad2Deg and set it to the transform.