UI朝向相机

public class LookAtCamera : MonoBehaviour
{
    private enum Mode
    {
        LookAt,
        LookAtInverted,
        Forward,
        ForwardInverted,
    }

    [SerializeField] private Mode mode;

    void LateUpdate()
    {
        switch (mode)
        {
            case Mode.LookAt:
                transform.LookAt(Camera.main.transform);
                break;

            case Mode.LookAtInverted:
                Vector3 dirFromCamera = transform.position - Camera.main.transform.forward;
                transform.LookAt(dirFromCamera);
                break;

            case Mode.Forward:
                transform.forward = Camera.main.transform.forward;
                break;

            case Mode.ForwardInverted:
                transform.forward = -Camera.main.transform.forward;
                break;

        }
    }
}