UI Tweaks, ChildEnumerator, ComponentAdded-Handlers

GlitchyEngine/src/World/Entity.bf

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 
 using internal GlitchyEngine.World;
 
@@ -24,13 +25,53 @@ namespace GlitchyEngine.World
 			_scene = scene;
 		}
 
+		public ChildEnumerator EnumerateChildren => .(this);
+
 		public bool IsValid => _entity.IsValid;
 
+		public Entity? Parent
+		{
+			get
+			{
+				var cmp = GetComponent<TransformComponent>();
+
+				if (cmp.Parent == .InvalidEntity)
+					return null;
+
+				return .(cmp.Parent, _scene);
+			}
+			set
+			{
+				if (value == null)
+				{
+					var cmp = GetComponent<TransformComponent>();
+					cmp.Parent = .InvalidEntity;
+				}
+				else
+				{
+					Entity parent = value.Value;
+
+					if (parent.Scene != _scene)
+					{
+						Log.EngineLogger.AssertDebug(false);
+						return;
+					}
+
+					var cmp = GetComponent<TransformComponent>();
+					cmp.Parent = parent._entity;
+				}
+			}
+		}
+
 		public T* AddComponent<T>(T value = T()) where T: struct, new
 		{
 			Log.EngineLogger.AssertDebug(!HasComponent<T>(), scope $"Entity already has component.");
 
-			return _scene._ecsWorld.AssignComponent<T>(_entity, value);
+			T* component = _scene._ecsWorld.AssignComponent<T>(_entity, value);
+
+			_scene.[Friend]OnComponentAdded(this, typeof(T), component);
+
+			return component;
 		}
 
 		public T* GetComponent<T>() where T: struct, new
@@ -51,5 +92,41 @@ namespace GlitchyEngine.World
 
 			_scene._ecsWorld.RemoveComponent<T>(_entity);
 		}
+
+		public struct ChildEnumerator : IEnumerator<Entity>, IDisposable
+		{
+			private WorldEnumerator<TransformComponent> _transformEnum;
+
+			private EcsEntity _entity;
+			private Entity _currentChild;
+
+			public this(Entity entity)
+			{
+				_entity = entity.Handle;
+				_transformEnum = entity.Scene._ecsWorld.Enumerate<TransformComponent>();
+				_currentChild = .(.InvalidEntity, entity.Scene);
+			}
+
+			public Entity Current => _currentChild;
+
+			public Result<Entity> GetNext() mut
+			{
+				while (true)
+				{
+					(EcsEntity entity, TransformComponent* transform) = Try!(_transformEnum.GetNext());
+
+					if (transform.Parent == _entity)
+					{
+						_currentChild.[Friend]_entity = entity;
+						return .Ok(_currentChild);
+					}
+				}
+			}
+
+			public void Dispose()
+			{
+				_transformEnum.Dispose();
+			}
+		}
 	}
 }