Description
Context
After #599 is merged, a Loader has update and draw functions and the new PausedAfterLoader even has a child actor that it manually calls update/draw on. A Loader is just a custom Scene at its heart that just can't use resources. There are several problems right now:
- Loader must manually handle actors it controls
- There are no lifecycle events for itself or its actors
- We have to manually handle input when loading vs. letting scene infrastructure take care of it
- There's custom plumbing to wait for a loader vs. just using scene transitioning/plumbing to do it once
load()Promise resolves
Proposal
I propose making Loader an interstitial scene by default and allowing it to be extendable/overridable. It won't be the root scene but it'll be a scene that maybe gets deactivated/removed after it's promise returns. It can extend Scene but implement ILoadable as well. Engine will just need some slight refactoring to accommodate the change but I don't think it'll be difficult.
We could even combine Scene and ILoadable so that goToScene returns a promise that resolves when Scene.load() returns. So Scene just becomes ILoadable and then we have transitions as well. Then the engine could call update/draw but Scene would not update/draw its actors until it's done loading. To try the new API, we could have a new method loadScene(name): Promise<any> that we could expose that would run the loading logic.