BagarBuildGame/FreeCam/Assets/Scripts/FreeCam.cs

using UnityEngine;
using UnityEngine.InputSystem;

public class FreeCam : MonoBehaviour
{
    [Header("Controls")]

    public float moveSpeed = 10f;
    public bool ghost = true;

    [Header("Sensitivity")]

    public float XAxisSensitivity = 30f;
    public float YAxisSensitivity = 30f;

    [Space]

    [Range(0, 89)] public float MaxXAngle = 60f;

    // privates

    private Vector2 _inputMouse;
    private Vector2 _velocity;
    private CharacterController _controller;

    private float _rotationX;


    private void Start()
    {
        // TODO remove - doesn't belong here - test only
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;

        _inputMouse = Vector2.zero;
        _velocity = Vector2.zero;
        _controller = gameObject.GetComponent<CharacterController>();

        _rotationX = 0;
    }

    // Update is called once per frame
    // TODO test if checking (input values = 0) to avoid calculus reduces CPU usage
    private void Update()
    {
        float rotationHorizontal = _inputMouse.x * XAxisSensitivity * Time.deltaTime;
        float rotationVertical = _inputMouse.y * YAxisSensitivity * Time.deltaTime;

        // always rotate Y in global world space to avoid gimbal lock
        transform.Rotate(Vector3.up * rotationHorizontal, Space.World);

        float rotationY = transform.localEulerAngles.y;

        _rotationX += rotationVertical;
        _rotationX = Mathf.Clamp(_rotationX, -MaxXAngle, MaxXAngle);

        transform.localEulerAngles = new Vector3(-_rotationX, rotationY, 0);

        float translationX = _velocity.x * moveSpeed * Time.deltaTime;
        float translationZ = _velocity.y * moveSpeed * Time.deltaTime;

        Vector3 _move = new Vector3(translationX, 0f, translationZ);

        // ghost directly moves transform. non-ghost uses CharacterController collision detection
        if (ghost) {
            transform.Translate(_move);
        } else {
            _move = transform.TransformVector(_move);
            _controller.Move(_move);
        }
    }

    public void OnLook(InputValue value)
    {
        Vector2 valueAsVector2 = value.Get<Vector2>();
        _inputMouse.x = valueAsVector2.x;
        _inputMouse.y = valueAsVector2.y;
    }

    public void OnMovement(InputValue value)
    {
        Vector2 valueAsVector2 = value.Get<Vector2>();
        _velocity.x = valueAsVector2.x;
        _velocity.y = valueAsVector2.y;
    }
}