Unity Camera Movement in Game view like Scene View with filtering

SmoothGameCameraMovement.cs

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


// Moves Camera similar to how camera is moved in the Unity view port. Drop the scrip on the game object which has the camera and you wish to move. 

public class SmoothGameCameraMovement : MonoBehaviour
{
    public  float lateralSpeed         = 0.0015f;
    public  float LongitudinalSpeed    = 0.0008f;
    public  float verticalSpeed        = 0.001f;
    public  float mouseMoevementSpeed  = 0.2f;
    public  float fovChangeSpeed       = 0.0008f;
    public  float ShiftMultiplyer      = 4f;
    public  bool  InvertedY            = false;

    // ------------------------------------------------------

    // these need to be > 0 and <= 1. closer to 0 is smoother movement 
    public  float verticalFilter       = 0.003f;  
    public  float lateralFilter        = 0.005f;
    public  float LongitudinalFilter   = 0.005f;
    public  float mouseFilter          = 0.04f;
    public  float fovFilter            = 0.0001f;

    // ------------------------------------------------------

    private float vertical;
    private float lateral;
    private float longitudinal;
    private float speedMultiplyer =  1f;
    private float inversion       = -1f;
    private float fovGain;


    private GameObject TransformDummy;
    private Camera     mainCam;


    void Start()
    {
        if (InvertedY) inversion =  1f;
        else           inversion = -1f;

        if (TransformDummy == null) TransformDummy = new GameObject("TransformDummy");
        TransformDummy.transform.rotation= this.transform.rotation;


        mainCam = this.GetComponent<Camera>();
        if (mainCam == null) mainCam = this.transform.GetComponentInChildren<Camera>();
        if (mainCam == null) mainCam = Camera.main;
        if (mainCam == null) Debug.LogWarning("the Class Move Camera could not find any camera.");

    }

    void Update()
    {

        // -------------------------------------------------------------------------------------------------------


        // ========================================
        // Speed Multiplyer
        speedMultiplyer = Mathf.Lerp(speedMultiplyer, 1f, 0.1f);
        if (Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.Mouse1))
        {
            speedMultiplyer += 0.2f * timeStep();
            speedMultiplyer = Mathf.Clamp(speedMultiplyer, 1f, ShiftMultiplyer);
        }



        // ========================================
        // Left Right Movement

        lateral  = Mathf.Lerp(lateral, 0f, lateralFilter * timeStep());
        lateral  = Mathf.Clamp(lateral, -1f, 1f);

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

        if (Input.GetKey(KeyCode.Mouse1)) lateral += x * lateralSpeed* timeStep();

        this.transform.position += this.transform.right * lateral * speedMultiplyer * timeStep();

        // ========================================
        // Foward Backward Movement

        longitudinal = Mathf.Lerp(longitudinal, 0f, LongitudinalFilter * timeStep());
        longitudinal = Mathf.Clamp(longitudinal, -1f, 1f);

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

        if (Input.GetKey(KeyCode.Mouse1)) longitudinal += y * LongitudinalSpeed;
        this.transform.position += this.transform.forward * longitudinal* speedMultiplyer;

        // ========================================
        // Up Down Movement

        vertical = Mathf.Lerp(vertical, 0f, verticalFilter);
        
        if (Input.GetKey(KeyCode.E) && Input.GetKey(KeyCode.Mouse1)) vertical += verticalSpeed * timeStep(); // UP 
        if (Input.GetKey(KeyCode.Q) && Input.GetKey(KeyCode.Mouse1)) vertical -= verticalSpeed * timeStep(); // DOWN 


        this.transform.position += this.transform.up * vertical * speedMultiplyer * timeStep();

        // ========================================
        // Mouse Movement X

        float mouseX = Input.GetAxis("Mouse X");
        if (Input.GetKey(KeyCode.Mouse1)) TransformDummy.transform.Rotate(Vector3.up * mouseX* mouseMoevementSpeed * timeStep(), Space.World);
        

        // ========================================
        // Mouse Movement Y

        float mouseY = Input.GetAxis("Mouse Y");
        if (Input.GetKey(KeyCode.Mouse1)) TransformDummy.transform.Rotate(TransformDummy.transform.right * -1f * mouseY* mouseMoevementSpeed * timeStep(), Space.World);


        this.transform.rotation = Quaternion.Slerp(this.transform.rotation, TransformDummy.transform.rotation, mouseFilter * timeStep());


        if (mainCam == null) return;

        // FOV
        fovGain = Mathf.Lerp(fovGain, 0f, fovFilter * timeStep());
        fovGain = Mathf.Clamp(fovGain, -1f, 1f);

        float mScrollDelta = Input.mouseScrollDelta.y*-1f;
        if (Input.GetKey(KeyCode.Mouse1)) fovGain += mScrollDelta * fovChangeSpeed * timeStep();
        mainCam.fieldOfView += fovGain; 

    }

    float timeStep() {
        return Time.deltaTime / 0.0066f; }
    
}