UnityEditor.HandleUtility.CalcRayPlaceOffset C# (CSharp) Method

        internal static float CalcRayPlaceOffset(Transform[] objects, Vector3 normal)
        {
            return INTERNAL_CALL_CalcRayPlaceOffset(objects, ref normal);
        }

        public void OnSceneDrag(SceneView sceneView)
        {
            GameObject target = base.target as GameObject;

            switch (PrefabUtility.GetPrefabType(target))
            {
            case PrefabType.Prefab:
            case PrefabType.ModelPrefab:
            {
                Event     current = Event.current;
                EventType type    = current.type;
                if (type != EventType.DragUpdated)
                {
                    if (type == EventType.DragPerform)
                    {
                        string uniqueNameForSibling = GameObjectUtility.GetUniqueNameForSibling(null, dragObject.name);
                        dragObject.hideFlags = HideFlags.None;
                        Undo.RegisterCreatedObjectUndo(dragObject, "Place " + dragObject.name);
                        EditorUtility.SetDirty(dragObject);
                        DragAndDrop.AcceptDrag();
                        Selection.activeObject             = dragObject;
                        HandleUtility.ignoreRaySnapObjects = null;
                        EditorWindow.mouseOverWindow.Focus();
                        dragObject.name = uniqueNameForSibling;
                        dragObject      = null;
                        current.Use();
                        break;
                    }
                    if (type == EventType.DragExited)
                    {
                        if (dragObject != null)
                        {
                            UnityEngine.Object.DestroyImmediate(dragObject, false);
                            HandleUtility.ignoreRaySnapObjects = null;
                            dragObject = null;
                            current.Use();
                        }
                        break;
                    }
                }
                else
                {
                    if (dragObject == null)
                    {
                        dragObject           = (GameObject)PrefabUtility.InstantiatePrefab(PrefabUtility.FindPrefabRoot(target));
                        dragObject.hideFlags = HideFlags.HideInHierarchy;
                        dragObject.name      = target.name;
                    }
                    if (HandleUtility.ignoreRaySnapObjects == null)
                    {
                        HandleUtility.ignoreRaySnapObjects = dragObject.GetComponentsInChildren <Transform>();
                    }
                    DragAndDrop.visualMode = DragAndDropVisualMode.Copy;
                    object obj3 = HandleUtility.RaySnap(HandleUtility.GUIPointToWorldRay(current.mousePosition));
                    if (obj3 != null)
                    {
                        RaycastHit hit = (RaycastHit)obj3;
                        float      num = 0f;
                        if (Tools.pivotMode == PivotMode.Center)
                        {
                            float num2 = HandleUtility.CalcRayPlaceOffset(HandleUtility.ignoreRaySnapObjects, hit.normal);
                            if (num2 != float.PositiveInfinity)
                            {
                                num = Vector3.Dot(dragObject.transform.position, hit.normal) - num2;
                            }
                        }
                        dragObject.transform.position = Matrix4x4.identity.MultiplyPoint(hit.point + ((Vector3)(hit.normal * num)));
                    }
                    else
                    {
                        dragObject.transform.position = HandleUtility.GUIPointToWorldRay(current.mousePosition).GetPoint(10f);
                    }
                    if (sceneView.in2DMode)
                    {
                        Vector3 position = dragObject.transform.position;
                        position.z = PrefabUtility.FindPrefabRoot(target).transform.position.z;
                        dragObject.transform.position = position;
                    }
                    current.Use();
                }
                break;
            }
            }
        }