Unity - Rotate around point tool - test 1

RotationHelper.cs

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

[InitializeOnLoad]
public class RotationHelper
{

    private static bool enabled;
    
    static RotationHelper()
    { 
        EditorApplication.update += Update;
        SceneView.onSceneGUIDelegate += OnSceneGUIDelegate;
    }

    private static int selectedAxis = 2;
    
    private static Event lastEvent;
    static void OnSceneGUIDelegate(SceneView sceneView)
    {
        var e = Event.current;
        if (e == null)
            return;
        
        lastEvent = e;

        var controlId = 0;
        if (enabled)
        {
            controlId = GUIUtility.GetControlID(FocusType.Passive);
            
            DrawUI();
        }

        switch (e.type)
        {
                case EventType.MouseDown:
                    if (e.button == 0 && enabled)
                    {
                        GUIUtility.hotControl = controlId;
                        Event.current.Use();

                        if (rotating)
                        {
                            
                        }
                        else
                        {
                            rotating = true;
                            selectedPoint = lastSelectedPoint;
                        }
                    }

                    break;
                
                case EventType.MouseDrag:
                    if (rotating && e.button == 0)
                    {
                        var axis = Vector3.up;
                        if (selectedAxis == 1)
                            axis = selectedGo.transform.right;
                        if (selectedAxis == 3)
                            axis = selectedGo.transform.forward; 
                        
                        selectedGo.transform.RotateAround(selectedPoint, axis, 20f * e.delta.x * Time.smoothDeltaTime);
                    }

                    break;
                
                case EventType.KeyDown:
                    if (e.keyCode == KeyCode.J)
                    {
                        enabled = !enabled;
                        if (!enabled)
                            rotating = false;
                    }

                    if (e.keyCode == KeyCode.Alpha1)
                        selectedAxis = 1;
                    if (e.keyCode == KeyCode.Alpha2)
                    {
                        selectedAxis = 2;
                        
                        GUIUtility.hotControl = controlId;
                        Event.current.Use();
                    }

                    if (e.keyCode == KeyCode.Alpha3)
                        selectedAxis = 3;
                    
                    if (e.keyCode == KeyCode.Escape)
                    {
                        if (rotating)
                            rotating = false;
                        else
                            enabled = false;
                    }

                    break;
        }
    }
    
    static void Update()
    {
        if (enabled)
            HandleActiveMode();
    }

    private static bool rotating;
    private static Vector3 selectedPoint;
    private static Vector3 lastSelectedPoint;
    private static GameObject selectedGo;

    private static Camera camera;
    
    private static void HandleActiveMode()
    {
        if (Selection.activeGameObject == null)
            return;

        if (Camera.current == null || lastEvent == null)
            return;

        camera = Camera.current;
        selectedGo = Selection.activeGameObject;
        
        var mousePos = new Vector3(lastEvent.mousePosition.x, camera.pixelHeight - lastEvent.mousePosition.y, 0);

        if (!rotating)
        {
            var ray = HandleUtility.GUIPointToWorldRay(mousePos);
//        Debug.DrawRay(ray.origin, ray.direction * 2000f, Color.red, 2f);

            var ray2 = camera.ScreenPointToRay(mousePos);
//        Debug.DrawRay(ray2.origin, ray2.direction * 2000f, Color.blue, 2f);

            lastSelectedPoint = FindClosestPoint(selectedGo, ray2);
        }
        
    }

    private static void DrawUI()
    {
        if (camera == null)
            return;

        Vector3 point;
        if (rotating)
        {
            Handles.color = Color.red;
            point = selectedPoint;
        }
        else
        {
            Handles.color = Color.blue;
            point = lastSelectedPoint;
        }
        
        Handles.DrawSolidDisc(point, camera.transform.forward * -1f, 0.1f);
        
    }
    private static float DistanceToRay(Vector3 point, Ray ray)
    {
        var distance = Vector3.Distance(ray.origin, point);
        var angle = Vector3.Angle(ray.direction, point - ray.origin);
        
        return (distance * Mathf.Sin(angle * Mathf.Deg2Rad));
    }
    
    private static Vector3 FindClosestPoint(GameObject go, Ray ray)
    {
        //collect vertices
        var meshFilters = go.GetComponentsInChildren<MeshFilter>();

        var vertices = new List<Vector3>();
        
        foreach (var meshFilter in meshFilters)
        {
            if (meshFilter.sharedMesh == null)
                continue;

            foreach (var vertex in meshFilter.sharedMesh.vertices)
            {
                vertices.Add(meshFilter.transform.TransformPoint(vertex));
            }
        }
        
        //find
        var closestVertex = Vector3.zero;
        var minDistance = float.MaxValue;
        
        foreach (var vertex in vertices)
        {
            var dist = DistanceToRay(vertex, ray);
//            Debug.Log(vertexPos + " d = " + dist);
            
            if (dist < minDistance)
            {
                closestVertex = vertex;
                minDistance = dist;
            }
        }

        return closestVertex;
    }
}