how to set z rotation to be always 0

Questions & Answers
1

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class mouseLook : MonoBehaviour
{
    public float mouseSensitivity = 100f;
    public Transform playerBody;
    // Start is called before the first frame update
    void Start()
    {
        Cursor.lockState = CursorLockMode.Locked;
    }

    // Update is called once per frame
    void Update()
    {
        float mouseX = Input.GetAxis("Mouse X") * mouseSensitivity * Time.deltaTime;
        float mouseY = Input.GetAxis("Mouse Y") * mouseSensitivity * Time.deltaTime;

        playerBody.Rotate(Vector3.up * mouseX);
        playerBody.Rotate(Vector3.right * -mouseY);

    }
}
2

put this last in update:

playerBody.rotation=new Vector3(playerBody.rotation.x,playerBody.rotation.y,0);

or you can set the constraints in the inspector.