[FEATURE] OnUnload or a way to know if the scene will be unloaded in OnFinalize

[SoraTehk]

Feature destription

So I have a problem when I'm:

• Preloading assets with OnInitialize
• Releasing them in OnFinalize
  ...for a persistent scene, in which it OnFinalize also get called when pushing in a new scene

[mackysoft]

Can you provide more details？

[SoraTehk]

Wait, I'm sorry, I misunderstood the package. It seems like Navigathena doesn't support additive scenes. I thought:

• Push/Pop: Doesn't unload the previous scene
• Change: Unloads all scenes and loads the target scene
• Replace: Unloads the top scene and loads the target scene
• Reload: Reload head scene (keep all previous scene intact)

Based on that, how would you handle additive scenes? Should I just use Unity's built-in SceneManager? Because if I do, I will lose Navigathena's lifecycle events.

[SoraTehk]

I just realize, in my Splash scene:

await Addressables.LoadSceneAsync("Levels/Core/Core.unity");

And on my Core's ISceneEntryPoint.OnEnter

GlobalSceneNavigator.Instance.Change(new AddressableSceneIdentifier("Levels/MainMenu/MainMenu.unity"));

This code unload my Core scene, is this normal behaviour?

[mackysoft]

@SoraTehk
Hi, sorry for the late response. I’ve been tied up with work and personal matters.

Regarding the design for reliable release, I haven’t had a chance to work out a proper approach yet.
I’ll start thinking about the design now and update Navigathena accordingly.

[mackysoft]

Next, I will answer the question about handling multi-scenes (although I think it's a little late).

For the sake of keeping a clean and deterministic navigation history, Navigathena does not treat additive “sub-scenes” as a first-class design target. Once you allow arbitrary multi-scene composition, the degrees of freedom become too high, the project architecture tends to get more complex, and it becomes harder to maintain over time.

Navigathena goal is to manage coarse-grained, high-level scenes (i.e., “screen-sized” scenes for games/apps). If you need additional sub-scenes (e.g., HUD, stage variations, UI overlays, etc.), I believe those should be managed inside each parent scene. In practice, that means the parent scene receives any necessary identifiers (stage ID, UI mode, etc.) and then performs its own sub-scene load/unload using UnityEngine.SceneManagement (or equivalent) from the destination scene’s SceneEntryPoint / SceneLifecycle.

[mackysoft]

I just realize, in my Splash scene:

await Addressables.LoadSceneAsync("Levels/Core/Core.unity");
And on my Core's ISceneEntryPoint.OnEnter

GlobalSceneNavigator.Instance.Change(new AddressableSceneIdentifier("Levels/MainMenu/MainMenu.unity"));
This code unload my Core scene, is this normal behaviour?

In Navigathena, the first SceneEntryPoint found at runtime becomes the starting point of the scene history/lifecycle. So if Core is the scene that contains that first SceneEntryPoint, then Core is treated as the “current/origin” scene managed by Navigathena.

In that case, when you call:

GlobalSceneNavigator.Instance.Change(new AddressableSceneIdentifier("Levels/MainMenu/MainMenu.unity"));

from Core’s OnEnter, Navigathena will switch to MainMenu and unload the origin scene (i.e., Core) as part of its normal transition flow. So yes, if the above assumption is true, this behavior is expected.

If you want Core to be persistent, it’s better to keep it out of Navigathena scene history. Typical approaches are:

• Remove SceneEntryPoint from Core and initialize it via Unity lifecycle methods (Awake/Start), or
• Load Core additively as a “root/persistent” scene, and let Navigathena manage only the UI/gameplay scenes.

[mackysoft]

In practice, for a typical Splash -> MainMenu setup, what I’ve done is:

1. Use Splash as the first scene that contains a SceneEntryPoint (i.e., the starting point for Navigathena’s lifecycle/history),
2. During Splash, load the persistent Root/Core scene additively (so it stays resident),
3. Then, still from Splash’s lifecycle, call Navigathena to transition to the main scene (e.g., MainMenu).

With this structure, Navigathena manages only the “screen scenes” (MainMenu, Gameplay, etc.), while the Root/Core scene remains persistent and is not treated as an origin scene to unload.

[mackysoft]

Next: Reliable release/cleanup design