How can I grab a reference of a game-object in a scene from a prefab

Question

currently I am working on a Equipment system that will Instantiate Game objects into the scene from a list, prior to this I was not using a Instantiation system with just keeping the Game Objects Active in the scene at all time.

Now with Instantiating the Game Object(Prefab) I am running into the error of Loosing the References when I instantiate them, I have looked at various other articles before such as this Discussion here:

However I am looking at alternative ways other than using Tags as this system may use a large amount of tags decreasing game performance overtime, would anyone know different methods as to saving references from a scene into a prefab?

So as this is a new system I am really just looking for suggestions on how to save references of scene game-objects into a prefab, as my old system was just holding the game objects active in the scene and not actually instantiating them, once again I would love to hear different types of methods, something more than just using Tags.

The References im trying to save are three Transform Elements from a script attached to my Prefab they are the following

    public Transform camPos;
    public Transform aimLocation;
    public Transform crosshairLocation;

Currently I am just dragging and dropping the gameobjects from the scene into the public fields in the script

Since this will be a major system I would like to not want to use tags for this system. But it is definitely a Valid option I am just looking for other methods for saving references of scene game-objects into a prefab When Instantiating the prefab into the scene,

Thank you for taking the time to read and any suggestions would be greatly Appreciated!

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Answer 1

You can not save scene references in prefabs, for obvious reasons (what happens if you instantiate that prefab into another scene?). Your prefab needs to discover the objects it needs after it's instantiated. I'm not a huge fan of the tag system in Unity (or any other system that uses strings as identifiers, too much room for error). I'd recommend you take any of these three approaches:

1. Make the transforms you need (cam pos, aim location, etc.) singletons if there's ever only going to be one of each. You'd make a script class specifically for each one, make that class a singleton, and put it on the game objects. Then, after your prefab is instantiated, you can do something like this: camPos = CamPos.Instance.transform; You can read up on the singleton pattern here.

2. If there's going to be more than one of each, group all related objects into a single hierarchy (that is, make them all the child of a single game object). For example, if there are going to be many characters and each is going to have a separate aim location, you can make aim location a child of the character game object. Then, in your prefab (take care to make the prefab a child of the same root game object as well), you can do something along these lines: camPos = transform.root.GetComponentInChildren<CamPos>().transform; Better yet, you can have a component that has references to all such objects, and attach one to the root game object. Then, you can do: camPos = transform.root.GetComponent<ReferenceRepository>().CamPos;

3. Initialize the prefabs when they're instantiated. For example, say you have a player class that instantiates a weapon and already has a reference to the camPos. You can do it like this: var weapon = Instantiate<Weapon>(myWeaponPrefab); weapon.CamPos = camPos; Note however that when you assign public fields this way, they will only be accessible once Start is called. In other words, they won't be available in Awake.

That said, I don't think making stuff like aim location and crosshair location separate objects is a very good idea anyway. You should have a player/human/pawn class, and that class can provide this information to other objects that need it.