create camera script to report it's current viewport via the event bus

scenes/player/Camera.cs

@@ -0,0 +1,20 @@
+using Godot;
+using System;
+
+public class Camera : Camera2D
+{
+    private Event _event;
+
+    public override void _Ready()
+    {
+        _event = GetNode<Event>("/root/Event");
+    }
+
+    public override void _PhysicsProcess(float delta)
+    {
+        var rect = GetViewportRect();
+        var owner = (Node2D) Owner;
+        rect.Position = owner.Position - rect.Size / 2;
+        _event.EmitSignal("CameraView", rect);
+    }
+}

scripts/Event.cs

@@ -14,4 +14,6 @@ public sealed class Event : Node
 	delegate void PlayerTouched();
 	[Signal]
 	delegate void DebugState(string state);
+	[Signal]
+	delegate void CameraView(Rect2 rect);
 }