Summary

The scene layer is composed by combining three types of data.

• Layer
  Data representing a unit of one screen.
• Transition
  Data representing transitions between layers.
• Loader
  Data representing the components in a Layer.

These data are similar to those of MonoBehaviour, which is a They are customizable Behaviour and can be inherited and implemented freely.
Some custom Behaviours are also available as presets. However, for more flexible game development, customization may be necessary for specific projects.

This page explains how to create a custom Behaviour.

Custom Layer

To customize a Layer, inherit from LayerBehaviour.
Since a Layer is data that represents a unit of a single screen, it eliminates the need for awkward components that conventionally tend to be placed at the root of the scene.
In addition, when transferring data during screen transitions, it used to be necessary to "escape data to DontDestroyOnload before unloading." but since all layers are always on-memory, it is possible to "transfer the data held in a layer to the next layer as it is.

Create Script

1. Select [Right-click > Create > SceneLayer > Layer Behaviour] on the Project view.
2. Enter a name for the LayerBehaviour.(Example:Title)
3. Right-click on the SceneLayerEditor.
4. Create a Layer and select BehaviourType from Inspector.
5. Set up the Script you just created.
   

Event Callback

OnInitialize

Initialization process.
Called only once.

OnEntry

Processing at Layer Entry.
The initialization process to be performed each time a scene is opened should be written here.

OnExit

Processing at Layer Exit.
Destruction processing to be performed each time you leave the scene should be written here.

OnUpdate

Processing at Layer Update.
Called every frame between OnEntry and OnExit.

OnTransit something

A callback county that describes the transition process.
It is a coroutine, and the transition is not complete until this callback is completed.
Therefore, if there are items that need to be loaded manually, or if you want to prepare a transitional effect, you can implement it here.

The call timing and layer rules for each event function are as follows

Event Callback	Timing	Call Layer
OnPreTransitFrom	Before transition starts.	Destination
OnPreTransitTo	Before transition starts.	Source
OnTransitFrom	In transition.	Destination
OnTransitTo	In transition.	Source
OnPostTransitFrom	After transition completed.	Destination
OnPostTransitTo	After transition completed.	Source
OnPreParentTransitFrom	Before transition starts of the parent Layer.	Child Layer of Destination
OnPreParentTransitTo	Before transition starts of the parent Layer.	Child Layer of Source
OnParentTransitFrom	In transition of the parent Layer.	Child Layer of Destination
OnParentTransitTo	In transition of the parent Layer.	Child Layer of Source
OnPostParentTransitFrom	After transition completed of the parent Layer.	Child Layer of Destination
OnPostParentTransitTo	After transition completed of the parent Layer.	Child Layer of Source
OnPreChildTransit	efore transition starts of the child Layer.	Parent Layer of destination and source
OnChildTransit	In transition of the child Layer.	Parent Layer of destination and source
OnPostChildTransit	After transition completed of the child Layer.	Parent Layer of destination and source

In transition … Between OnExit and OnEntry Before transition starts … Before OnExit
After transition completed … After OnEntry
See Sequence Events for more information.

OnCheckError

Error checking process.
If there is an error in the input parameters, the If error information is added to the passed argument, it can be checked on the editor and can be detected as a runtime error at startup.

// Arg1：Error message (required)
// Others：The name of the SerializeField that caused the problem, if any.
result.Add(new ErrorObject("Error Message.", nameof(_reasonMember)));

OnDuplicatedAsset (for editors)

Processing when duplicating an asset.
The source of the duplicate is passed as an argument.
If there is a value you want to take over when duplicating an asset, you can copy it.

OnChangeBehaviourTo (for editors)

Processing at the time of Behaviour change.
If there are any values you want to inherit from LayerBehaviour after the change, you can copy them here.

Custom Transition

To customize a Transition, extend TransitionBehaviour.
Customizing transitions makes it possible to programmatically describe transition conditions.
It is also possible to describe events during transitions, making it possible to implement common processes such as "clearing the cache during transition" in one place.

Crete Script

1. Select [Right click > Create > SceneLayer > Transition Behaviour] on the Project view.
2. Enter a name for the LayerBehaviour.(Example:Title)
3. Right-click on a layer in the SceneLayerEditor.
4. Create a Transition and select BehaviourType from Inspector.
5. Specify the Script you just created.
   

Event Callback

IsTransitable(Required)

If Transition is enabled, this function is checked every frame.
If true is returned when a transition is enabled, the transition is executed.

OnInitialize

Initialization process.
Called only once.

OnTransit something

A callback county that describes the transition process.
These callbacks are coroutines, and the transition is not complete until this callback is completed.
Therefore, if there is processing that needs to be done before the transition completes, it should be implemented here.

Event Callback	Timing
OnPreTransit	Before transition starts.
OnTransit	In transition.
OnPostTransit	After transition completed.

In transition … Between OnExit and OnEntry Before transition starts … Before OnExit
After transition completed … After OnEntry
See Sequence Events for more information.

OnCheckError

Error checking process.
If there is an error in the input parameters, the If error information is added to the passed argument, it can be checked on the editor and can be detected as a runtime error at startup.

// Arg1：Error message (required)
// Others：The name of the SerializeField that caused the problem, if any.
result.Add(new ErrorObject("Error Message.", nameof(_reasonMember)));

OnDuplicatedAsset (for editors)

Processing when duplicating an asset.
The source of the duplicate is passed as an argument.
If there is a value you want to take over when duplicating an asset, you can copy it.

OnChangeBehaviourTo (for editors)

Processing at the time of Behaviour change.
If there are any values you want to inherit from TransitionBehaviour after the change, you can copy them here.

Custom Loader

Loader inherits from LoaderBehaviour for customization.
The Loader is responsible for loading, generating, destroying, and releasing screen elements in a registered Layer.
However, the actual asset management varies from project to project. Customization is expected to go through a project-specific asset manager.

Create Script

1. Select [Right click > Create > SceneLayer > Loader Behaviour] on the Project view.
2. Enter a name for the Loader.(Example:AssetLoader)
3. Open Script and implement the process of your choice.
4. Open Layer's Inspector.
5. Create a Loader from the [+] button and select `BehaviourType.
6. Specify the Script you just created.
   

Event Callback

GetInstance(Required)

Return the instantiated instance.

GetInstanceType(Required)

Returns the type of instance to be instantiated.
If the type is unknown, object is acceptable, but it is preferable that the type is narrowed down as much as possible.
If the type is narrowed down, it will be easier to use Receive Loader instance events in Layer.

Load(Required)

Loading process.
If you want to use your own loading process or asset manager, implement it here.
(You can write the loading process in LayerBehaviour.OnTransit something, but it is recommended to implement it here because it can handle preloading.)
It is also possible to load multiple assets that do not have a specific target at once.

Unload(Required)

Release process.

InstantiateObject(Required)

Make the loaded object ready for use.
If it is a GameObject, Instantiate.
If it is a Scene, LoadSceneAsync.
If it is a BGM, you may start playback here.

DestroyObject(Required)

Destroy instances created by InstantiateObject.

OnInitialize

Initialization process.
Called only once.

OnCheckError

Error checking process.
If there is an error in the input parameters, the If error information is added to the passed argument, it can be checked on the editor and can be detected as a runtime error at startup.

// Arg1：Error message (required)
// Others：The name of the SerializeField that caused the problem, if any.
result.Add(new ErrorObject("Error Message.", nameof(_reasonMember)));

OnDuplicatedAsset (for editors)

Processing when duplicating an asset.
The source of the duplicate is passed as an argument.
If there is a value you want to take over when duplicating an asset, you can copy it.

OnChangeBehaviourTo (for editors)

Processing at the time of Behaviour change.
If there are any values you want to inherit from LoaderBehaviour after the change, you can copy them here.