AtomicMain.cs

using AtomicEngine;
using AtomicPlayer;

public class AtomicMain : AppDelegate
{
    private UIView uiView_;

    public override void Start()
    {
        uiView_ = new UIView();
        var rootLayout = new UILayout();
        rootLayout.Axis = UI_AXIS.UI_AXIS_X;
        rootLayout.Rect = uiView_.Rect;
        rootLayout.LayoutPosition = UI_LAYOUT_POSITION.UI_LAYOUT_POSITION_GRAVITY;
        uiView_.AddChild(rootLayout);

        Player player = GetSubsystem<Player>();

        string[] sampleTypes = { "Scene1", "Scene2", "Scene3" };
        foreach (var sample in sampleTypes)
        {
            var button = new UIButton();
            button.Text = sample;

            button.SubscribeToEvent<WidgetEvent>(button, e =>
            {
                player.UnloadScene(player.CurrentScene);
                Scene newScene = player.LoadScene($"Scenes/{button.Text}.scene");
                
                Vector<Camera> cameras = new Vector<Camera>();
                newScene.GetComponents(cameras, true);

                Viewport viewport = GetSubsystem<Renderer>().GetViewport(0);
                viewport.SetScene(newScene);
                viewport.SetCamera(cameras[0]);
            });

            rootLayout.AddChild(button);
        }
    }
}