add: LoadingScene, ProxyNode

src/Scenes/LoadingScene.cs

@@ -0,0 +1,30 @@
+using Godot;
+using Polonium.DataStructures;
+using Polonium.Managers;
+
+namespace Polonium.Scenes;
+
+public abstract partial class LoadingScene<T> : Scene
+    where T : ProgressInfo
+{
+    public Scene AfterLoaded { get; set; }
+
+    private double CoolDown { get; set; } = 0;
+
+    public LoaderManager<T> Manager { get; set; }
+
+    protected abstract void ConsumeProgressInfo(T progressInfo);
+
+    public override void _Process(double delta)
+    {
+        CoolDown += delta;
+        if (CoolDown < 1)
+            return;
+        CoolDown = 0;
+        T progress = Manager.QueryProgress();
+        ConsumeProgressInfo(progress);
+        if(Manager.Finished)
+            PoloniumRegistry.Instance.RootScene.SwitchScene(AfterLoaded);
+        base._Process(delta);
+    }
+}