hierachy and parent child system updates

- started working on an editor hierarchy window
- testing filters
- testing parent child relations without system
- testing root component
- thinking about how to get all entities that are not a child, but also don't have an other identifying component

Nerfed.Editor/Editor/EditorGui.cs

@@ -66,6 +66,11 @@ namespace Nerfed.Editor
             UpdateDock();
 
             ImGui.ShowDemoWindow();
+
+            foreach (MoonTools.ECS.System system in Program.editorSystems)
+            {
+                system.Update(Engine.Timestep);
+            }
         }
     }
 }

Nerfed.Editor/Program.cs

@@ -1,7 +1,9 @@
 using MoonTools.ECS;
+using Nerfed.Editor.Systems;
 using Nerfed.Runtime;
 using Nerfed.Runtime.Components;
 using Nerfed.Runtime.Systems;
+using Nerfed.Runtime.Util;
 using System.Numerics;
 
 namespace Nerfed.Editor;
@@ -10,6 +12,7 @@ internal class Program
 {
     private static readonly World world = new World();
     private static List<MoonTools.ECS.System> systems = new List<MoonTools.ECS.System>();
+    public static List<MoonTools.ECS.System> editorSystems = new List<MoonTools.ECS.System>();
 
     private static void Main(string[] args)
     {
@@ -23,15 +26,25 @@ internal class Program
 
     private static void HandleOnInitialize()
     {
-        systems.Add(new ParentSystem(world));
+        //systems.Add(new ParentSystem(world));
         systems.Add(new LocalToWorldSystem(world));
+        editorSystems.Add(new EditorHierarchyWindow(world));
 
-        Entity ent1 = world.CreateEntity();
+        Entity ent1 = world.CreateEntity("parent");
         world.Set(ent1, new LocalTransform(new Vector3(1, 0, 0), Quaternion.Identity, Vector3.One));
 
-        Entity ent2 = world.CreateEntity();
+        Entity ent2 = world.CreateEntity("child");
         world.Set(ent2, new LocalTransform(new Vector3(0, 1, 0), Quaternion.Identity, Vector3.One));
-        world.Set(ent2, new Parent(ent1));
+        Transform.SetParent(world, ent2, ent1);
+
+        Entity ent3 = world.CreateEntity("entity3");
+        world.Set(ent3, new Root());
+        Transform.SetParent(world, ent3, ent2);
+
+        Entity ent4 = world.CreateEntity("entity4");
+        world.Set(ent4, new Root());
+
+        Entity ent5 = world.CreateBaseEntity("entity5");
 
         // Open project.
         // Setip EditorGui.
@@ -50,6 +63,8 @@ internal class Program
 
 
         // Try Catch UserCode Update.
+
+        world.FinishUpdate();
     }
 
     private static void HandleOnRender()

Nerfed.Editor/Systems/EditorHierarchyWindow.cs

@@ -0,0 +1,60 @@
+using ImGuiNET;
+using MoonTools.ECS;
+using Nerfed.Runtime.Components;
+
+namespace Nerfed.Editor.Systems
+{
+    internal class EditorHierarchyWindow : MoonTools.ECS.DebugSystem
+    {
+        private readonly Filter rootEntitiesWithTransformFilter;
+        private readonly Filter rootEntitiesFilterBroken;
+        private readonly Filter rootEntitiesFilter;
+
+        public EditorHierarchyWindow(World world) : base(world)
+        {
+            rootEntitiesWithTransformFilter = FilterBuilder.Include<LocalTransform>().Exclude<Child>().Build();
+
+            // TODO: this doesn't work.
+            rootEntitiesFilterBroken = FilterBuilder.Exclude<Child>().Build();
+
+            // Maybe the parent/child functions should add a root component when not being a child.
+            rootEntitiesFilter = FilterBuilder.Include<Root>().Build(); 
+
+            // Maybe instead of a root, if we need a component that is always on an entity and has some use we could create something like a VersionComponent which only hold an int.
+            // The version would update each time something changes on the entity.
+            // 
+        }
+
+        public override void Update(TimeSpan delta)
+        {
+            ImGui.Begin("Hierarchy");
+
+            foreach (Entity entity in rootEntitiesWithTransformFilter.Entities)
+            {
+                DrawEntityAndChildren(entity);
+            }
+
+            ImGui.NewLine();
+
+            foreach (Entity entity in rootEntitiesFilter.Entities)
+            {
+                DrawEntityAndChildren(entity);
+            }
+
+            ImGui.End();
+        }
+        
+        private void DrawEntityAndChildren(in Entity entity, int depth = 0)
+        {
+            string label = new string(' ', depth);
+            ImGui.Text($"{label}{entity.ID} | {GetTag(entity)}");
+
+            depth++;
+            ReverseSpanEnumerator<Entity> childEntities = World.InRelations<ChildParentRelation>(entity);
+            foreach (Entity childEntity in childEntities)
+            {
+                DrawEntityAndChildren(childEntity, depth);
+            }
+        }
+    }
+}