GameObjects Lists in BoxCollider2D?

This isn't really a post for 2D, it's seems like a post for the Scripting forum because, honestly, the above isn't even valid C# code and won't even compile but you are asking about specific mechanics and not the fact that the code won't even compile which is a little confusing.

I can only assume you mean a Generic List i.e. List<T> so instead of:

Code (CSharp):

1. public List GameObject onObjects;

you mean something like:

Code (CSharp):

1. public List<GameObject> onObjects;

I understand your question but it seems you need to first address the C# usage issue?

I'll hold off moving your post to scripting forum though.

 

To answer your question given that you've put all the appropriate GameObject to show/hide in those list then you'd do something like this:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. public class ActivationScript : MonoBehaviour
5. {
6.     public List<GameObject> onObjects;
7.     public List<GameObject> offObjects;
8.  
9.     void OnTriggerEnter2D(Collider2D other)
10.     {
11.         if (other.gameObject.tag == "Player")
12.         {
13.             SetEnterExitVisibility(true);
14.         }
15.     }
16.  
17.     private void OnTriggerExit2D(Collider2D other)
18.     {
19.         if (other.gameObject.tag == "Player")
20.         {
21.           SetEnterExitVisibility(false);
22.         }
23.     }
24.  
25.     private void SetEnterExitVisibility(bool isEntering)
26.     {
27.         foreach(var obj in onObjects)
28.             obj.SetActive(isEntering);
29.  
30.         foreach(var obj in offObjects)
31.             obj.SetActive(!isEntering);
32.     }
33. }

You're better off though simply making it so that the above trigger only interacts with the "Player" layer. Using tags isn't something you have to do and should avoid unless you have to use them.

 

Nothing intrinsically bad about them but they're not used by the physics engine at all.

The physics engine provides the low-level and fast ability for you to select which layers can contact other layers. If you use this, not only does the physics engine not need to calculate unnecessary layer/layer interactions but you can also simply check which layer you've got. This is shown in all the basic physics tutorials though and it's what the Layer Collision Matrix provides.

What we see though is devs allowing everything to contact everything and then simply deciding if it's something they're interested in with a tag, mostly with triggers. It works but it's also wasted work.

Also, writing hardcoded strings all over your code isn't very scalable and is pretty fragile to change.