Unity Script: FPS Player Movement

 This is a First Person character controller.  Move with WASD, Jump with Space. 

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

public class PlayerMovement : MonoBehaviour

{

    public CharacterController controller;

    public float speed = 12f;

    public float gravity = -9.81f;

    public float jumpHeight = 3f;

    public Transform groundCheck;

    public float groundDistance = 0.4f;

    public LayerMask groundMask;

    Vector3 velocity;

    bool isGrounded;

    // Start is called before the first frame update

    void Start()

    {

       

    }

    // Update is called once per frame

    void Update()

    {

        isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);

        if(isGrounded && velocity.y < 0){

            velocity.y = -2f;

        }

        float x = Input.GetAxis("Horizontal");

        float z = Input.GetAxis("Vertical");

        Vector3 move = transform.right * x + transform.forward * z;

        controller.Move(move * speed * Time.deltaTime);

        if(Input.GetButtonDown("Jump") && isGrounded){

            velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);

        }

        velocity.y += gravity * Time.deltaTime;

        controller.Move(velocity * Time.deltaTime);

    }

}