added forge addon

addons/forge/nodes/EffectShapeCast2D.cs

@@ -0,0 +1,99 @@
+// Copyright © Gamesmiths Guild.
+
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using Gamesmiths.Forge.Core;
+using Gamesmiths.Forge.Godot.Core;
+using Godot;
+
+namespace Gamesmiths.Forge.Godot.Nodes;
+
+[GlobalClass]
+[Icon("uid://dni75h8pnigh2")]
+public partial class EffectShapeCast2D : ShapeCast2D
+{
+	private readonly HashSet<GodotObject> _lastFrameColliders = [];
+
+	private EffectApplier? _effectApplier;
+
+	[Export]
+	public Node? EffectOwner { get; set; }
+
+	[Export]
+	public Node? EffectSource { get; set; }
+
+	[Export]
+	public int EffectLevel { get; set; } = 1;
+
+	[Export]
+	public EffectTriggerMode TriggerMode { get; set; }
+
+	private IForgeEntity? OwnerEntity => EffectOwner as IForgeEntity;
+
+	private IForgeEntity? SourceEntity => EffectSource as IForgeEntity;
+
+	public override void _Ready()
+	{
+		if (EffectOwner is not null && EffectOwner is not IForgeEntity)
+		{
+			GD.PushError($"{nameof(EffectOwner)} must implement {nameof(IForgeEntity)}.");
+		}
+
+		base._Ready();
+
+		_effectApplier = new EffectApplier(this);
+	}
+
+	public override void _PhysicsProcess(double delta)
+	{
+		base._PhysicsProcess(delta);
+
+		Debug.Assert(_effectApplier is not null, $"{_effectApplier} should have been initialized on _Ready().");
+
+		var collisions = GetCollisionCount();
+
+		var collidersThisFrame = new List<GodotObject>();
+		for (var i = 0; i < collisions; i++)
+		{
+			GodotObject current = GetCollider(i);
+			var hadLast = _lastFrameColliders.Contains(current);
+
+			_lastFrameColliders.Add(current);
+			collidersThisFrame.Add(current);
+
+			// Enter: is colliding now, wasn't colliding before.
+			if (current is Node currentNode && !hadLast)
+			{
+				if (TriggerMode == EffectTriggerMode.OnStay)
+				{
+					_effectApplier.AddEffects(currentNode, OwnerEntity, SourceEntity, EffectLevel);
+				}
+				else if (TriggerMode == EffectTriggerMode.OnEnter)
+				{
+					_effectApplier.ApplyEffects(currentNode, OwnerEntity, SourceEntity, EffectLevel);
+				}
+			}
+		}
+
+		// Exit: Was colliding before, isn't colliding now.
+		foreach (GodotObject? lastCollider in _lastFrameColliders.Except(collidersThisFrame))
+		{
+			_lastFrameColliders.Remove(lastCollider);
+
+			if (lastCollider is not Node lastNode)
+			{
+				continue;
+			}
+
+			if (TriggerMode == EffectTriggerMode.OnStay)
+			{
+				_effectApplier.RemoveEffects(lastNode);
+			}
+			else if (TriggerMode == EffectTriggerMode.OnExit)
+			{
+				_effectApplier.ApplyEffects(lastNode, OwnerEntity, SourceEntity, EffectLevel);
+			}
+		}
+	}
+}