public static void OnSceneGUI(SceneView sceneView)
        {
            if (EditorApplication.isPlayingOrWillChangePlaymode)
            {
                return;
            }

            CameraUtility.InitDistanceChecks(sceneView);
            SelectionUtility.HandleEvents();
            InitTools();

            HandleBuilderEvents();
            {
                UpdateTool();

                if (instance.activeTool != null)
                {
                    if (RealtimeCSG.CSGSettings.EnableRealtimeCSG)
                    {
                        // handle the tool
                        var sceneSize = sceneView.position.size;
                        var sceneRect = new Rect(0, 0, sceneSize.x, sceneSize.y - ((CSG_GUIStyleUtility.BottomToolBarHeight + 4) + 17));

                        instance.activeTool.HandleEvents(sceneRect);
                    }
                    else
                    {
                        if (Event.current.type == EventType.Repaint)
                        {
                            var brushes         = instance.filteredSelection.BrushTargets;
                            var wireframes      = new List <GeometryWireframe>(brushes.Length);
                            var transformations = new List <Matrix4x4>(brushes.Length);
                            for (int i = 0; i < brushes.Length; i++)
                            {
                                var brush = brushes[i];
                                if (!brush)
                                {
                                    continue;
                                }

                                if (brush.ChildData == null ||
                                    !brush.ChildData.Model)
                                {
                                    continue;
                                }

                                var brushTransformation = brush.compareTransformation.localToWorldMatrix;

                                wireframes.Add(BrushOutlineManager.GetBrushOutline(brushes[i].brushNodeID));
                                transformations.Add(brushTransformation);
                            }
                            if (wireframes.Count > 0)
                            {
                                CSGRenderer.DrawSelectedBrushes(instance.zTestLineMeshManager, instance.noZTestLineMeshManager,
                                                                wireframes.ToArray(), transformations.ToArray(),
                                                                ColorSettings.SelectedOutlines, GUIConstants.thickLineScale);
                            }
                            MaterialUtility.LineDashMultiplier      = 1.0f;
                            MaterialUtility.LineThicknessMultiplier = 1.0f;
                            MaterialUtility.LineAlphaMultiplier     = 1.0f;
                            instance.zTestLineMeshManager.Render(MaterialUtility.ZTestGenericLine);
                            instance.zTestLineMeshManager.Render(MaterialUtility.ZTestGenericLine);
                        }
                    }
                }
            }

            int sceneWindowId   = GUIUtility.GetControlID(SceneWindowHash, FocusType.Passive);
            var sceneWindowType = Event.current.GetTypeForControl(sceneWindowId);

            if (sceneWindowType == EventType.Repaint)
            {
                if (currentEditorWindows.Count > 0)
                {
                    for (int i = 0; i < currentEditorWindows.Count; i++)
                    {
                        currentEditorWindows[i].Repaint();
                    }
                    return;
                }
            }

            if (sceneWindowType == EventType.MouseMove)
            {
                SceneDragToolManager.IsDraggingObjectInScene = false;
            }

            if (RealtimeCSG.CSGSettings.EnableRealtimeCSG)
            {
                if (sceneView && sceneWindowType != EventType.Used && !SceneDragToolManager.IsDraggingObjectInScene)
                {
                    if (currentEditorWindows.Count == 0)
                    {
                        try
                        {
                            Handles.BeginGUI();
                            Rect windowRect = new Rect(Vector2.zero, sceneView.position.size);
                            EditModeSelectionGUI.HandleWindowGUI(windowRect);
                        }
                        finally
                        {
                            Handles.EndGUI();
                        }
                    }
                }
            }
        }
        //void OnSceneGUI() <- paints -everything- again for every selected brush
        public static void OnSceneGUI(SceneView sceneView)
        {
            if (EditorApplication.isPlayingOrWillChangePlaymode)
            {
                return;
            }


            /*
             * int prevHotControl		= GUIUtility.hotControl;
             * int prevKeyboardControl = GUIUtility.keyboardControl;
             *
             * // make it impossible for the tool to click in the bottom bar area
             * int bottomBarId	 = GUIUtility.GetControlID (BottomBarInputHash, FocusType.Passive);
             * bool forceRevert = false;
             * //if (GUIUtility.hotControl == 0)
             * {
             *      var bottomBarRect = sceneView.position;
             *      var min = bottomBarRect.min;
             *      var max = bottomBarRect.max;
             *
             *      min.y = max.y - (GUIStyleUtility.BottomToolBarHeight + 18);
             *
             *      bottomBarRect.min = min;
             *      bottomBarRect.max = max;
             *
             *      if (bottomBarRect.Contains(Event.current.mousePosition))
             *      {
             *              GUIUtility.hotControl	   = bottomBarId;
             *              GUIUtility.keyboardControl = bottomBarId;
             *              forceRevert = true;
             *      }
             * }
             */
            SelectionUtility.HandleEvents();
            InitTools();

            HandleBuilderEvents();
            //HandleYMode();
            {
                UpdateTool();

                if (instance.activeTool != null)
                {
                    if (RealtimeCSG.CSGSettings.EnableRealtimeCSG)
                    {
                        // handle the tool
                        var sceneSize = sceneView.position.size;
                        var sceneRect = new Rect(0, 0, sceneSize.x, sceneSize.y - ((GUIStyleUtility.BottomToolBarHeight + 4) + 17));
                        //var originalEventType = Event.current.type;
                        //if (originalEventType == EventType.MouseMove ||
                        //	originalEventType == EventType.MouseUp)
                        //	holdingDownMouse = false;

                        //var mousePos = Event.current.mousePosition;
                        //if (originalEventType == EventType.Layout ||
                        //	originalEventType == EventType.Repaint ||
                        //	sceneRect.Contains(mousePos) ||
                        //	holdingDownMouse)
                        instance.activeTool.HandleEvents(sceneRect);

                        //if (originalEventType == EventType.MouseDown ||
                        //	originalEventType == EventType.MouseDrag)
                        //	holdingDownMouse = true;
                    }
                    else
                    {
                        if (Event.current.type == EventType.Repaint)
                        {
                            var brushes      = instance.filteredSelection.BrushTargets;
                            var wireframes   = new List <GeometryWireframe>(brushes.Length);
                            var translations = new List <Vector3>(brushes.Length);
                            for (int i = 0; i < brushes.Length; i++)
                            {
                                var brush = brushes[i];
                                if (!brush)
                                {
                                    continue;
                                }

                                var brushCache = InternalCSGModelManager.GetBrushCache(brush);
                                if (brushCache == null ||
                                    brushCache.childData == null ||
                                    !brushCache.childData.Model)
                                {
                                    continue;
                                }

                                var brushTranslation = brushCache.compareTransformation.modelLocalPosition + brushCache.childData.ModelTransform.position;

                                wireframes.Add(BrushOutlineManager.GetBrushOutline(brushes[i].brushID));
                                translations.Add(brushTranslation);
                            }
                            if (wireframes.Count > 0)
                            {
                                CSGRenderer.DrawSelectedBrushes(instance.zTestLineMeshManager, instance.noZTestLineMeshManager,
                                                                wireframes.ToArray(), translations.ToArray(),
                                                                ColorSettings.SelectedOutlines, ToolConstants.thickLineScale);
                            }
                            MaterialUtility.LineDashMultiplier      = 1.0f;
                            MaterialUtility.LineThicknessMultiplier = 1.0f;
                            MaterialUtility.LineAlphaMultiplier     = 1.0f;
                            instance.zTestLineMeshManager.Render(MaterialUtility.ZTestGenericLine);
                            instance.zTestLineMeshManager.Render(MaterialUtility.ZTestGenericLine);
                        }
                    }
                }
            }

            /*
             * // reset the control so the bottom bar can take over
             * if (forceRevert)
             * {
             *      GUIUtility.hotControl		= prevHotControl;
             *      GUIUtility.keyboardControl	= prevKeyboardControl;
             * }
             */

            int sceneWindowId   = GUIUtility.GetControlID(SceneWindowHash, FocusType.Passive);
            var sceneWindowType = Event.current.GetTypeForControl(sceneWindowId);

            if (sceneWindowType == EventType.Repaint)
            {
                if (currentEditorWindows.Count > 0)
                {
                    for (int i = 0; i < currentEditorWindows.Count; i++)
                    {
                        currentEditorWindows[i].Repaint();
                    }
                    return;
                }
            }

            if (sceneWindowType == EventType.MouseMove)
            {
                SceneTools.IsDraggingObjectInScene = false;
            }

            if (RealtimeCSG.CSGSettings.EnableRealtimeCSG)
            {
                if (sceneView != null && sceneWindowType != EventType.Used && !SceneTools.IsDraggingObjectInScene)
                {
                    if (currentEditorWindows.Count == 0)
                    {
                        try
                        {
                            Handles.BeginGUI();
                            Rect windowRect = new Rect(Vector2.zero, sceneView.position.size);
                            CSGBrushEditorGUI.HandleWindowGUI(windowRect);
                        }
                        finally
                        {
                            Handles.EndGUI();
                        }
                    }
                }
            }
        }