Orbit Camera Controller for Unity

OrbitCameraController.cs

using UnityEngine;
using UnityEditor;

#if UNITY_EDITOR
[RequireComponent(typeof(Camera))]
public class OrbitCameraController : MonoBehaviour
{
    public bool _alignWithViewAtStart = true;
    public bool _alignSceneViewAtQuit = false;
    public bool _enableBallControl = false;
    public bool _enableRollControl = false;

    private Vector3 _pivot;
    private Camera _camera;
    private const float _translateCoef = 0.02f;
    private const float _rotateCoef = 4.0f;
    private const float _zoomCoef = 0.1f;
    private const float _rollCoef = 2.0f;
    
    void OnEnable()
    {
        _camera = GetComponent<Camera>();
        if (_alignWithViewAtStart && _camera.targetDisplay == Display.activeEditorGameViewTarget)
        {
            SceneView sv = SceneView.lastActiveSceneView;
            _pivot = sv.pivot;
            transform.rotation = sv.rotation;
            transform.position = _pivot - transform.forward * sv.cameraDistance;
        }
    }
    void OnDisable()
    {
        if (_alignSceneViewAtQuit && _camera.targetDisplay == Display.activeEditorGameViewTarget)
        {
            SceneView sv = SceneView.lastActiveSceneView;
            sv.pivot = _pivot;
            sv.rotation = transform.rotation;
            sv.size = Vector3.Distance(_pivot, transform.position) * Mathf.Sin(sv.cameraSettings.fieldOfView * 0.5f * Mathf.Deg2Rad);
        }
    }
    void LateUpdate()
    {
        if(_camera.targetDisplay != Display.activeEditorGameViewTarget) return;
        if (Input.GetKey(KeyCode.LeftAlt) || Input.GetKey(KeyCode.RightAlt))
        {
            if (Input.GetMouseButton(0))
                if (Input.GetKey(KeyCode.LeftControl) || Input.GetKey(KeyCode.RightControl)) Translate();
                else RotateAroundPivot();
            else if (Input.GetMouseButton(2)) Translate();
            else if (Input.GetMouseButton(1))
                if (Input.GetKey(KeyCode.LeftControl) || Input.GetKey(KeyCode.RightControl))
                    if (_enableRollControl) Roll();
                    else RotateAroundOrigin();
                else Zoom();
            transform.position += transform.forward * Input.mouseScrollDelta.y;
        }
    }
    void Translate()
    {
        float coef = Vector3.Distance(_pivot, transform.position) * Mathf.Atan(_camera.fieldOfView * 0.5f) * _translateCoef;
        if(Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.LeftShift)) coef *= 2.0f;
        Vector3 move = coef * (transform.right * Input.GetAxis("Mouse X") + transform.up * Input.GetAxis("Mouse Y"));
        _pivot -= move;
        transform.position -= move;
    }
    void RotateAroundPivot()
    {
        float coef = _rotateCoef;
        if(Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.LeftShift)) coef *= 2.0f;
        transform.RotateAround(_pivot, _enableBallControl ? transform.up : Vector3.up, coef * Input.GetAxis("Mouse X"));
        transform.RotateAround(_pivot, transform.right, coef * -Input.GetAxis("Mouse Y"));
    }
    void RotateAroundOrigin()
    {
        float coef = _rotateCoef;
        if(Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.LeftShift)) coef *= 2.0f;
        transform.Rotate(coef * -Input.GetAxis("Mouse Y"), coef * Input.GetAxis("Mouse X"), 0);
    }
    void Zoom()
    {
        float coef = _zoomCoef * Vector3.Distance(_pivot, transform.position);
        if(Input.GetKey(KeyCode.LeftShift) || Input.GetKey(KeyCode.LeftShift)) coef *= 2.0f;
        transform.position += coef * transform.forward * Input.GetAxis("Mouse X");
        transform.position -= coef * transform.forward * Input.GetAxis("Mouse Y");
    }
    void Roll()
    {
        transform.Rotate(Vector3.forward, _rollCoef * Input.GetAxis("Mouse X"));
    }
}

[CustomEditor(typeof(OrbitCameraController))]
public class OrbitCameraControllerEditor : Editor
{
    public override void OnInspectorGUI()
    {
        base.OnInspectorGUI();
        if(GUILayout.Button("Reset Scene View"))
        {
            SceneView sv = SceneView.lastActiveSceneView;
            sv.ResetCameraSettings();
            sv.pivot = Vector3.zero;
            sv.rotation = Quaternion.LookRotation(new Vector3(-1, -.7f, -1));
            sv.size = 10f;
        }
        EditorGUILayout.LabelField("Alt Left : Orbit Around Pivot");
        EditorGUILayout.LabelField("Alt Left Ctrl : Translate");
        EditorGUILayout.LabelField("Alt Middle : Translate");
        EditorGUILayout.LabelField("Alt Right or Wheel : Zoom");
        EditorGUILayout.LabelField("Alt Right Ctrl : Roll or Rotate");
        EditorGUILayout.LabelField("Shift : x2");
        EditorGUILayout.HelpBox("To feedback, Copy Component of the Transform on runtime then Paste Component Values after quit.", MessageType.None);
    }
}
#endif

see http://ossan-engineer.blogspot.com/2022/06/orbitcameracontroller.html