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scenemanager [2021/02/08 01:00] uninomiconadmin [Build Pipeline] |
scenemanager [2022/01/30 19:55] (current) narry Added details about an undocumented quirk with occlusion culling in additive scenes |
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====== SceneManager ====== | ====== SceneManager ====== | ||
- | Notes: | ||
- | `SceneManager.sceneLoaded` is called *after* the loaded | + | ==== When does scene loading happen? ==== |
+ | Scene loading and unloading | ||
- | The Unity scene flushing pipeline works differently in the initialization phase of the player. Scene loads thats are queued during initialization are blocked and fully loaded before the game starts. For example, if SceneManager.LoadSceneAsync is called in the Awake of the very first scene (ie. called before the first Update), then the engine will wait to fully load that scene as well, before starting the first Update. | + | Player Loop Phases: |
- | + | * __Initialization__ | |
- | It is untested if this is also the case for SceneManager.UnloadSceneAsync. However, because Unity documentation mentions that that the scene loading queue is a pipeline, and only one AsyncOperation can progress at a time, I would suspect that the Engine simply " | + | |
- | + | ||
- | Phases: | + | |
- | + | ||
- | * Initialization | + | |
* Game Loop | * Game Loop | ||
* Early Update | * Early Update | ||
- | * `UpdatePreloading` | + | * __UpdatePreloading__ |
+ | * FixedUpdate | ||
* Update | * Update | ||
- | (The scene load pipeline is fully flushed) I don't yet know how it handles unloads if they are in the pipeline then, so if we need this behaviour we should debug and see how it works. If scene unloads get flushed too, we'll need to add a bit of logic for it, in the same way LoadSceneAsync does. | ||
- | The scene loading pipeline only seems to load one scene, every other frame. | + | ===== The Scene Loading Queue ===== |
+ | |||
+ | The scene loading | ||
+ | |||
+ | During the '' | ||
+ | |||
+ | The scene loading pipeline only seems to execute a single operation, every other frame.< | ||
* Frame N+0: Scene1 | * Frame N+0: Scene1 | ||
- | * Frame N+1: ---- | + | * Frame N+1: --- |
* Frame N+2: Scene 2 | * Frame N+2: Scene 2 | ||
- | * Frame N+3: ---- | + | * Frame N+3: --- |
* Frame N+4: Scene 3 | * Frame N+4: Scene 3 | ||
+ | |||
+ | |||
+ | ==== Initialization ==== | ||
+ | |||
+ | The Engine fully " | ||
+ | |||
+ | **All** AsyncOperations that are queued during initialization are fully loaded during initialization. For example, if '' | ||
+ | |||
+ | Scene unloads are probably flushed if they are in the pipeline, too.< | ||
===== Build Pipeline ===== | ===== Build Pipeline ===== | ||
- | Scenes are built during standalone in the following way: ' | + | Scenes are built during standalone |
- The active scenes are closed. | - The active scenes are closed. | ||
- Each Scene in the BuildSettings is opened. At this point prefabs are still prefab instances. | - Each Scene in the BuildSettings is opened. At this point prefabs are still prefab instances. | ||
- | - EditorSceneManager.sceneOpened callback is called. | + | - '' |
- Prefabs in the scene are flattened (turned into normal game objects). | - Prefabs in the scene are flattened (turned into normal game objects). | ||
- [[IProcessScene]] and PostProcessScene callbacks are called. | - [[IProcessScene]] and PostProcessScene callbacks are called. | ||
- The final scene file is saved into the standalone build file. | - The final scene file is saved into the standalone build file. | ||
- | - Repeat for next scene . | + | - Repeat for next scene. |
+ | |||
+ | ===== Sample Scene Load (Editor) ===== | ||
+ | |||
+ | Here is an example of a scene loading additively **in the middle** of a game, **in the editor**. Note that: | ||
+ | |||
+ | * Prefabs.MergePrefabs (turning prefabs into gameobjects) happens before any other callback. (editor only) | ||
+ | * Lightmapping is applied / loaded after Awake/ | ||
+ | * SceneManager.sceneLoaded happens after PostProcessScene. | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | ===== Scattered Notes ===== | ||
+ | * During a scene load (ie. Awake) the loading scene has '' | ||
+ | * During a scene unload (ie. Destroy) the unloading scene has '' | ||
+ | * '' | ||
+ | * When using '' | ||
+ | |||
+ | |||
+ | ---- | ||
+ | |||
+ | ===== API Notes: ===== | ||
+ | === SceneManager.sceneLoaded === | ||
+ | * Called **after** the loaded Scene Awakes. | ||
+ |