[c#] screen to local/object coordinates, best method

I have a number of objects, using playing cards for test, on top of each other like this:

The objects are perfectly lined out and then i click on Heart Queen (HQ) and get the following:

When i click on HQ i do make the HQ parent and the other yellow is child's as well as increase their sort order to get them on top. Here is the code i use for this:

Code (csharp):

1. print ("Here we go - " + MainScript.selectedGameObjectList.Count);
2.  
3.         firstRound = true;
4.  
5.         // Allocate all selected objects to the container
6.         foreach(GameObject aGameObject in MainScript.selectedGameObjectList) {
7.  
8.             if(firstRound) {
9.                 // At the first round do not add child as the first object is parent
10.  
11.                 theFirstGO = aGameObject;
12.  
13. //              theFirstGO.transform.renderer.sortingOrder = 100;
14.  
15.                 firstRound = false;
16.             }
17.             else {
18.                 // Add to parent
19.                 print (aGameObject.name + " / " + aGameObject.transform.position);
20.  
21.                 aGameObject.transform.parent = theFirstGO.transform;
22.                 aGameObject.collider2D.enabled = false;
23.  
24.             }
25.         }
26.  
27.         // Make sure the selected container, with all it's objects, get's on top
28.  
29.         theMainScript = new MainScript(); // Set up access to MainScript
30.         GameObject dummyGO;
31.  
32.         int lengthOfList = MainScript.selectedGameObjectList.Count;
33.  
34.         for(int zz = 0; zz < MainScript.selectedGameObjectList.Count; zz++) {
35.             MainScript.selectedGameObjectList[zz].transform.renderer.sortingOrder = 100; //transform.renderer.sortingOrder;
36.         }

However, my challenge is how to, except for the selected object (HQ) which get's on top, keep the position for the child's the parent after selection? I know there is some functions for some type of conversion like world to local etc. but have not been able to figure out how to do this?

Worst case i guess this needs to be done manually for each selected object, which i tried but not really got it perfect.

Not that it matters but in Objective-C/SpriteKit I would manually do it this way:

Code (csharp):

1. //////SAVE THE REALATIVE POSITION BETWEEN THE NODE ON SCREEN AND IN THE CONTAINER//////
2.  [_relativePositionDifferenceArray addObject:aNode.name];
3.  [_relativePositionDifferenceArray addObject:[NSNumber valueWithCGPoint:CGPointMake(aNode.position.x - _containerNode.position.x, aNode.position.y - _containerNode.position.y)]];
4.  [_relativePositionDifferenceArray addObject:[NSNumber numberWithFloat:aNode.zRotation]];

 

If you want to only move the parent object, you could try this and adjust/optimize it for your needs.

Code (csharp):

1.  
2. public Transform[] childs;
3. public bool onlyParent;
4. void Update()
5. {
6.      if (Input.GetKey(KeyCode.W))
7.      {
8.           transform.Translate(Vector3.forward * Time.deltaTime*5);
9.           if (onlyParent)
10.           {
11.                foreach (Transform c in childs)
12.                {
13.                     // move it into the opposite direction 'back' or  ' - Vector3.forward'
14.                     c.Translate(Vector3.back * Time.deltaTime*5);
15.                }
16.           }
17.      }
18.  
19.      // press C to assign all childs to the array
20.      if (Input.GetKeyDown(KeyCode.C))
21.      {
22.             childs = new Transform[transform.childCount];
23.             for (int i = 0; i < childs.Length; i++)
24.           {
25.                 childs[i] = transform.GetChild(i);
26.           }
27.      }
28. }
29.