idle_frame signal not being fired after SceneTree.ChangeScene() call

kitfox

I've written an asynchronous method (in C#) to handle screen transitions. After reading the docs for SceneTree, I thought it would be a good idea to wait for the frame_idle event to be fired after changing a scene to make sure my new scene is loaded before trying to access it. Trouble is, this signal does not seem to be fired. When I run the below code, the last thing printed to console is <5> and my fade in method is never called. What's going on? What's the right way to ensure a scene is loaded before trying to access it?

    void onBodyEntered(Node body)
    {
        if (body is Ball)
        {
            Fader fader = GetNode<Fader>(Fader.AUTOLOAD_PATH);

            SceneTree tree = GetTree();

            Task.Run(async () =>
            {
                GD.Print("<1>");
                await ToSignal(tree, "idle_frame");
                GD.Print("<2>");

                await fader.fadeOutAsync();
                GD.Print("<3>");

                await ToSignal(tree, "idle_frame");
                GD.Print("<4>");

                Error result;
                if (targetScene == "")
                {
                    result = tree.ReloadCurrentScene();
                }
                else
                    result = tree.ChangeScene(targetScene);

                GD.Print("<5>");

                await ToSignal(tree, "idle_frame");
                GD.Print("<6>");

                await fader.fadeInAsync();
                GD.Print("<7>");
            });
        }
    }

kitfox

Best I can figure out, once a scene has been removed from the scene tree, it will no longer receive signals from it. So since I was calling this from inside the scene that was being removed, maybe the scene was being destroyed before the code was being run? I was able to find a work around by moving this method to an autoloaded level that is never removed.

cybereality

If you remove a scene from the tree, it is effectively dead. It will still exist in memory (until you call queue_free() or free()) but it can't do anything and won't update.

Megalomaniak

removing from tree is useful for say object pooling, in case you know you want to have a maximum of n amounts of something in your scene at any one time and don't want to incur the object creation & freeing costs every time you remove and recreate them.