Add some props to ArenaExterior

BoundingBoxes/OcclusionTrigger.cs

@@ -0,0 +1,70 @@
+using Godot;
+using System.Linq;
+using System.Collections.Generic;
+
+namespace SupaLidlGame.BoundingBoxes;
+
+public partial class OcclusionTrigger : Area2D
+{
+    [Export]
+    public double FadeDuration { get; set; }
+
+    [Export]
+    public Godot.Collections.Array<string> Groups { get; set; }
+
+    private Tween _tween = null;
+
+    public override void _Ready()
+    {
+        Connect(SignalName.BodyEntered, new Callable(this, nameof(OnBodyEntered)));
+        Connect(SignalName.BodyExited, new Callable(this, nameof(OnBodyExited)));
+    }
+
+    private IEnumerable<CanvasItem> GetCanvasItems()
+    {
+        IEnumerable<IEnumerable<CanvasItem>> pack()
+        {
+            foreach (string group in Groups)
+            {
+                var nodes = GetTree().GetNodesInGroup(group)
+                    .OfType<CanvasItem>();
+
+                yield return nodes;
+            }
+        }
+
+        return pack().SelectMany(e => e);
+    }
+
+    private void OnBodyEntered(Node2D _)
+    {
+        if (IsInstanceValid(_tween))
+        {
+            _tween.Kill();
+        }
+
+        _tween = GetTree().CreateTween();
+        _tween.SetParallel();
+
+        foreach (var node in GetCanvasItems())
+        {
+            _tween.TweenProperty(node, "modulate", Colors.Transparent, FadeDuration);
+        }
+    }
+
+    private void OnBodyExited(Node2D _)
+    {
+        if (IsInstanceValid(_tween))
+        {
+            _tween.Kill();
+        }
+
+        _tween = GetTree().CreateTween();
+        _tween.SetParallel();
+
+        foreach (var node in GetCanvasItems())
+        {
+            _tween.TweenProperty(node, "modulate", Colors.White, FadeDuration);
+        }
+    }
+}