Question Scene Component

I still don't understand why we can't allow to attach component to scene. Are there any reason that scene must not contain component? Would it cause breaking change in some way?

 

Hey, are you trying to attach data to SceneAssets? if so you can use the "userData" field of the asset importer then create a custom Editor for "SceneAssetType", also if you need that data to be findable in scene you can create a class that implements "IProcessSceneWithReport" and move that data on scene.
Here is a small example on how to do it

Code (CSharp):

1.      
2.         public static bool TryGetData(string path, out SceneMetaData metaData)
3.         {
4.             var importer = AssetImporter.GetAtPath(path);
5.  
6.             var userData = importer.userData;
7.  
8.             if (string.IsNullOrEmpty(userData))
9.             {
10.                 metaData = default;
11.                 return false;
12.             }
13.  
14.             metaData = new SceneMetaData();
15.             EditorJsonUtility.FromJsonOverwrite(userData, metaData);
16.             return true;
17.         }
18.  
19.         public static void SetData(string targetPath, SceneMetaData data)
20.         {
21.             var importer = AssetImporter.GetAtPath(targetPath);
22.             var importerUserData = EditorJsonUtility.ToJson(data);
23.             if (importerUserData != importer.userData)
24.             {
25.                 importer.userData = importerUserData;
26.                 importer.SaveAndReimport();
27.             }
28.         }

 

Every Component has immediate access to .transform or .gameObject or .tag; those make no sense for a Scene. I can imagine all the horrible

if (transform == null)

types of checks to make sure a component remained safe to use if somehow attached to a Scene.

 

Because sometimes we don't want gameObject logic. We want to write scene logic

Sometimes we want something that will stay with the scene, manipulate other root GameObjects. And many core logic of the scene should not depend on existence or activation of object inside the scene

UX wise. When too many gameobject was spawned into the root of the scene it then become inconvenient to find core logic object. Also many times we don't know which gameObject should be attach the logic because it really not a gameobject specific logic

 

Being able to add custom data to scenes that would be available at runtime without jumping through hoops would be nice.

Unity does this internally with some data (OcclusionCullingSettings, RenderSettings, LightmapSettings and NavMeshSettings are all in the scene yaml file), so for things like those, it should be clear that this is useful.

For our game, we usually end up with some global ScriptableObject that has a scene-to-data Dictionary that we look up for things like 2D light settings and other per-scene data. If we could store it as a part of the scene file, and do SceneManager.GetActiveScene().GetData<DataType>() to load it at runtime, it'd be a lot more convenient.

 

I has two moments

1) When you need some data associated with scene. You could might use it before or after scene load.

2) You need some code associated with scene. Usualy before\after scene load\unload.