UnityCameraController

CameraController.cs

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


[RequireComponent(typeof(Camera))]

public class CameraController : MonoBehaviour
{
    enum MouseButton
    {
        LEFT = 0,
        RIGHT = 1,
        MIDDLE = 2,
    };

    [SerializeField]
    private GameObject FocusingObject = null;

    public float DistanceFromFocusingObject = 3.0f;

    public bool IsMouseControlActive = true;

    public KeyCode PositionResetKey = KeyCode.Space;

    private Vector3 FocusingObjInitPosition;
    private Vector3 ThisInitPosition;

    private Vector3 motionStartedMousePos;

    private const float CameraTrackingScale = 0.005f;
    private const float CameraRotationScale = 0.05f;

    void Start()
    {
        if (FocusingObject == null)
        {
            FocusingObject = new GameObject("FocusingObject");
            FocusingObject.transform.position = Vector3.zero;
        }

        this.transform.parent = FocusingObject.transform;
        var deltaVec = (this.transform.position - FocusingObject.transform.position);
        deltaVec = (deltaVec == Vector3.zero) ? (new Vector3(1, 1, 1)).normalized : deltaVec.normalized;
        this.transform.position = FocusingObject.transform.position + DistanceFromFocusingObject * deltaVec;
        this.transform.LookAt(FocusingObject.transform.position);
        FocusingObjInitPosition = FocusingObject.transform.position;
        ThisInitPosition = this.transform.position;
    }

    void Update()
    {
        if (IsMouseControlActive)
        {
            UpdateMouseEvent();
        }

        if (Input.GetKeyDown(PositionResetKey))
        {
            FocusingObject.transform.position = FocusingObjInitPosition;
            this.transform.position = ThisInitPosition;
        }

        this.transform.LookAt(FocusingObject.transform.position);
    }

    public void UpdateMouseEvent()
    {
        //checked new input system: https://blogs.unity3d.com/2019/10/14/introducing-the-new-input-system/

        float scroll = Input.GetAxis("Mouse ScrollWheel");
        if (scroll != 0.0f)
        {
            CameraDolly(scroll);
        }

        if(Input.GetMouseButtonDown((int)MouseButton.MIDDLE) || Input.GetMouseButtonDown((int)MouseButton.RIGHT))
        {
            this.motionStartedMousePos = Input.mousePosition;
        }

        if (Input.GetMouseButton((int)MouseButton.MIDDLE))
        {            
            CameraTrack(Input.mousePosition - this.motionStartedMousePos);
            this.motionStartedMousePos = Input.mousePosition;
        }

        if (Input.GetMouseButton((int)MouseButton.RIGHT))
        {
            CameraOutsideInRotation(Input.mousePosition - this.motionStartedMousePos);
            this.motionStartedMousePos = Input.mousePosition;
        }
        
    }

    private void CameraOutsideInRotation(Vector3 delta)
    {
        delta = (new Vector3(delta.y, delta.x, 0.0f)) * CameraRotationScale;
        FocusingObject.transform.localEulerAngles += delta;
    }

    private void CameraTrack(Vector3 delta)
    {
        delta = delta * CameraTrackingScale;
        FocusingObject.transform.Translate(Vector3.right * -delta.x);
        FocusingObject.transform.Translate(Vector3.up * -delta.y);
    }


    private void CameraDolly(float delta)
    {
        var deltaVec = (this.transform.position - FocusingObject.transform.position);
        var updatedDeltaVec = deltaVec * (1.0f + delta);

        if (updatedDeltaVec.magnitude > 0.01)
        {
            this.transform.position = this.FocusingObject.transform.position + updatedDeltaVec;
        }
        return;
    }
}