TransitionToScene (and variants) only unload the current active scene.

[Clozent]

When using TransitionToSceneAsync() to transition between scenes, I expected that the scene loader would unload all scenes under it's management when transitioning. Instead, no scene was unloaded at all, because I didn't make the scene I wished to unload the active scene.

This is a problem.

Unloading only the active scene is extremely limiting, as there is currently no way to transition from:

1. A scene that is not the active scene
2. A collection of scenes

What I propose is that ISceneLoader.TransitionToScene() and ISceneLoader.TransitionToScenes() would accept a scene or an array of scenes to unload, and that the implementations of these methods in SceneLoaderAsync, SceneLoaderCoroutine, and SceneLoaderUniTask would unload all managed scenes by default.

I know this will break backwards compatibility, but it doesn't seem like much of a problem, seeing as this package already broke some backwards compatibility in the past.

[joaoborks]

Hi @Clozent, thanks for your report.

I agree with you, simply unloading the active scene only covers a simple use case. It does not need to break compatibility though, we can just add new method alternatives for scene transition, such as:

1. Passing scenes to be unloaded

void TransitionToScenesAsync(ILoadSceneInfo[] targetScenes, int setIndexActive, ILoadSceneInfo[] unloadScenes, ILoadSceneInfo intermediateSceneReference = null)

2. Option to unload all managed scenes

void TransitionToScenesAsync(ILoadSceneInfo[] targetScenes, int setIndexActive, bool unloadAllScenes, ILoadSceneInfo intermediateSceneReference = null)

With the new methods, you'd have three options for transition:

1. Transition and unload the active scene (current implementation)
2. Transition and unload a group of scenes
3. Transition and unload all other managed scenes

What do you think? If you agree, I'll start working on it right away.

[Clozent]

Hi, overall, I think these new methods are a good way to solve this problem.

One thing is bugging me, though: the method void TransitionToScenesAsync(ILoadSceneInfo[] targetScenes, int setIndexActive, bool unloadAllScenes, ILoadSceneInfo intermediateSceneReference = null) changes it's behavior depending on a boolean (unloadAllScenes, in this case), which is, from my understanding, something a method should avoid.

Instead, I think it would be best to make the behavior a separate method, such as TransitionToScenesUnloadAll(...) (I don't think this is a good name for it, but I can't come up with anything better).

[joaoborks]

You're right, it'd be better to introduce a new method for unloading all scenes.

So to summarize, two new methods will be added:

1. TransitionToScenesFromScenes - unloads multiple provided scenes
2. TransitionToScenesFromAll - unloads all managed scenes

Not so sure about the names yet, but that's the scope. I'll start working on it today.

[joaoborks]

Adding a development note for my future self:

Check whether including #44 improves the experience when using TransitionToScenesFromScenes.