Babushka/scripts/CSharp/Common/SceneManagement/SceneTransitionThreaded.cs

using Godot;

namespace Babushka.scripts.CSharp.Common.SceneManagement;
public partial class SceneTransitionThreaded : CanvasLayer
{
    public static SceneTransitionThreaded Instance { get; private set; }
    
    // set to true if don't wanna use it
    public bool userCodeLoadCompleted = true;

    private ThreadedLoadingStateEn threadedLoadingState = ThreadedLoadingStateEn._none;
    public enum ThreadedLoadingStateEn
    {
        _none,
        _fading_in,
        _loading,
        _loading_user_code
    }
    
    [Export] private AnimationPlayer animationPlayer;
    private string scenePathThreaded = "";
    
    public override void _EnterTree()
    {
        Instance = this;
    }
    
    public override void _Process(double delta)
    {
        CheckLoadThreaded();
    }

    private void CheckLoadThreaded()
    {
        if (scenePathThreaded == "")
        { return; }

        if (threadedLoadingState == ThreadedLoadingStateEn._loading && ResourceLoader.LoadThreadedGetStatus(scenePathThreaded) == ResourceLoader.ThreadLoadStatus.Loaded)
        {
            OnResourceLoadThreadedComplete();
        }
        else if (threadedLoadingState == ThreadedLoadingStateEn._loading_user_code && userCodeLoadCompleted)
        {
            OnResourceLoadThreadedCompleteUserCode();
        }
    }
    
    public async void ChangeSceneToFile(string scenePath)
    {
        animationPlayer.Play("fadeIn");
        await ToSignal(animationPlayer, "animation_finished");
        GetTree().ChangeSceneToFile(scenePath);
        animationPlayer.Play("fadeOut");
    }

    public void OnFadeInCompletedThreaded()
    {
        if (scenePathThreaded == "")
        { return; }
        
        ResourceLoader.LoadThreadedRequest(scenePathThreaded);
        threadedLoadingState = ThreadedLoadingStateEn._loading;
    }
    
    // https://docs.godotengine.org/en/stable/tutorials/io/background_loading.html
    public void ChangeSceneToFileThreaded(string scenePath)
    {
        scenePathThreaded = scenePath;
        animationPlayer.Play("fadeIn");
        threadedLoadingState = ThreadedLoadingStateEn._fading_in;
    }
    
    private void OnResourceLoadThreadedComplete()
    {
        PackedScene loadedScene = (PackedScene)ResourceLoader.LoadThreadedGet(scenePathThreaded);
        //Node sceneInstance = loadedScene.Instantiate();
        GetTree().ChangeSceneToPacked(loadedScene);
        threadedLoadingState = ThreadedLoadingStateEn._loading_user_code;
    }

    private void OnResourceLoadThreadedCompleteUserCode()
    {
        animationPlayer.Play("fadeOut");
        scenePathThreaded = "";
        threadedLoadingState = ThreadedLoadingStateEn._none;
    }
}