How to make two or more objects stick together ?

Questions & Answers
1

Well I am making a jigsaw like game (2d) I’ve run over many like question that suggested to parent objects together, well that will make one object follow the other but not vice versa I want to drag either of the two objects and the other move along.

Any help ?

2

I don’t know how you are approaching your drag and drop and your combining of pieces. Here is a bit of code as an example of how it may be done. This may not be the best approach for your specific mechanics, but it show a proof of concept. To make the code simple, each visible piece has an empty game object as a parent. If pieces are combined, one of the two parents is abandoned. As mentioned in my comments above, the drag and drop moves the empty parent game object, not the child piece.

#pragma strict
import System.Collections.Generic;

private var offset : Vector3;

function OnMouseDown () {
	var v3 = Vector3(Input.mousePosition.x, Input.mousePosition.y, transform.parent.position.z - Camera.main.transform.position.z);
	v3 = Camera.main.ScreenToWorldPoint(v3);
	offset = transform.parent.position - v3;
}

function OnMouseDrag() {
	var v3 = Vector3(Input.mousePosition.x, Input.mousePosition.y, transform.parent.position.z - Camera.main.transform.position.z);
	v3 = Camera.main.ScreenToWorldPoint(v3);
	transform.parent.position = v3 + offset;
}

function Combine(piece : GameObject) {
	var transforms : List.<Transform> = new List.<Transform>();  
	var parent = piece.transform.parent;
	
	var trans = transform.parent;
	
	for (var child : Transform in transform.parent) {
		transforms.Add(child);
	}
	
	for (var child : Transform in transforms) {
		child.parent = parent;
    }
}

Note that the combine code transfers all siblings to the new parent. This will allow two collections of more than one piece to be combined.