From 5cc876fce9aafb3d091f8ba324ca435a54a40f21 Mon Sep 17 00:00:00 2001
From: max <max+github@vertexcolor.xyz>
Date: Tue, 15 Oct 2024 21:47:23 +0200
Subject: [PATCH] tree hierachy and selection test

---
 .../Components/SelectedInHierachy.cs          |   4 +
 .../Systems/EditorHierarchyWindow.cs          | 120 ++++++++++++++----
 Nerfed.Runtime/Systems/LocalToWorldSystem.cs  |   1 -
 3 files changed, 102 insertions(+), 23 deletions(-)
 create mode 100644 Nerfed.Editor/Components/SelectedInHierachy.cs

diff --git a/Nerfed.Editor/Components/SelectedInHierachy.cs b/Nerfed.Editor/Components/SelectedInHierachy.cs
new file mode 100644
index 0000000..8a46182
--- /dev/null
+++ b/Nerfed.Editor/Components/SelectedInHierachy.cs
@@ -0,0 +1,4 @@
+namespace Nerfed.Editor.Components;
+
+public readonly record struct SelectedInHierachy;
+public readonly record struct ClickedInHierarchy;
\ No newline at end of file
diff --git a/Nerfed.Editor/Systems/EditorHierarchyWindow.cs b/Nerfed.Editor/Systems/EditorHierarchyWindow.cs
index c44e513..2dc52cc 100644
--- a/Nerfed.Editor/Systems/EditorHierarchyWindow.cs
+++ b/Nerfed.Editor/Systems/EditorHierarchyWindow.cs
@@ -1,59 +1,135 @@
 using ImGuiNET;
 using MoonTools.ECS;
+using Nerfed.Editor.Components;
 using Nerfed.Runtime.Components;
 
 namespace Nerfed.Editor.Systems
 {
+    // Window that draws entities.
     internal class EditorHierarchyWindow : MoonTools.ECS.DebugSystem
     {
+        private const ImGuiTreeNodeFlags baseFlags = ImGuiTreeNodeFlags.OpenOnArrow | ImGuiTreeNodeFlags.OpenOnDoubleClick | ImGuiTreeNodeFlags.SpanAvailWidth;
+
         private readonly Filter rootEntitiesWithTransformFilter;
-        private readonly Filter rootEntitiesFilterBroken;
+        //private readonly Filter rootEntitiesFilterBroken;
         private readonly Filter rootEntitiesFilter;
 
+        private readonly EditorHierachySelectionSystem hierachySelectionSystem;
+
         public EditorHierarchyWindow(World world) : base(world)
         {
             rootEntitiesWithTransformFilter = FilterBuilder.Include<LocalTransform>().Exclude<Child>().Build();
 
             // TODO: this doesn't work.
-            rootEntitiesFilterBroken = FilterBuilder.Exclude<Child>().Build();
+            //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(); 
+            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.
-            // 
+            // Or a EditorComponent, just a component that always gets added when in editor mode.
+
+            hierachySelectionSystem = new EditorHierachySelectionSystem(world);
         }
 
         public override void Update(TimeSpan delta)
         {
             ImGui.Begin("Hierarchy");
 
-            foreach (Entity entity in rootEntitiesWithTransformFilter.Entities)
-            {
-                DrawEntityAndChildren(entity);
-            }
+            ImGuiTreeNodeFlags flags = baseFlags;
+            flags |= ImGuiTreeNodeFlags.DefaultOpen;
 
-            ImGui.NewLine();
-
-            foreach (Entity entity in rootEntitiesFilter.Entities)
+            if (ImGui.TreeNodeEx("World", flags))
             {
-                DrawEntityAndChildren(entity);
+                foreach (Entity entity in rootEntitiesWithTransformFilter.Entities)
+                {
+                    DrawEntityAndChildren(entity);
+                }
+
+                foreach (Entity entity in rootEntitiesFilter.Entities)
+                {
+                    DrawEntityAndChildren(entity);
+                }
+
+                ImGui.TreePop();
             }
 
             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)
+            hierachySelectionSystem.Update(delta);
+        }
+
+        private void DrawEntityAndChildren(in Entity entity)
+        {
+            ImGuiTreeNodeFlags flags = baseFlags;
+
+            if (!World.HasInRelation<ChildParentRelation>(entity))
             {
-                DrawEntityAndChildren(childEntity, depth);
+                flags |= ImGuiTreeNodeFlags.Leaf;
+            }
+
+            if (World.Has<SelectedInHierachy>(entity))
+            {
+                flags |= ImGuiTreeNodeFlags.Selected;
+            }
+
+            if (ImGui.TreeNodeEx($"{entity.ID} | {GetTag(entity)}", flags))
+            {
+                if (ImGui.IsItemClicked() && !ImGui.IsItemToggledOpen())
+                {
+                    World.Set(entity, new ClickedInHierarchy());
+                }
+
+                ReverseSpanEnumerator<Entity> childEntities = World.InRelations<ChildParentRelation>(entity);
+                foreach (Entity childEntity in childEntities)
+                {
+                    DrawEntityAndChildren(childEntity);
+                }
+
+                ImGui.TreePop();
+            }
+        }
+
+        // System for handling the selected entities in the hierachy.
+        private class EditorHierachySelectionSystem : MoonTools.ECS.System
+        {
+            private readonly Filter selectedEntities;
+            private readonly Filter clickedEntities;
+
+            public EditorHierachySelectionSystem(World world) : base(world)
+            {
+                selectedEntities = FilterBuilder.Include<SelectedInHierachy>().Build();
+                clickedEntities = FilterBuilder.Include<ClickedInHierarchy>().Build();
+            }
+
+            public override void Update(TimeSpan delta)
+            {
+                ImGuiIOPtr io = ImGui.GetIO();
+
+                if (!clickedEntities.Empty && !io.KeyCtrl)
+                {
+                    foreach (Entity entity in selectedEntities.Entities)
+                    {
+                        Remove<SelectedInHierachy>(entity);
+                    }
+                }
+
+                foreach (Entity entity in clickedEntities.Entities)
+                {
+                    // Unselect.
+                    if (Has<SelectedInHierachy>(entity))
+                    {
+                        Remove<SelectedInHierachy>(entity);
+                    }
+                    // Select.
+                    else
+                    {
+                        Set(entity, new SelectedInHierachy());
+                    }
+
+                    Remove<ClickedInHierarchy>(entity);
+                }
             }
         }
     }
diff --git a/Nerfed.Runtime/Systems/LocalToWorldSystem.cs b/Nerfed.Runtime/Systems/LocalToWorldSystem.cs
index ac48642..97b31c0 100644
--- a/Nerfed.Runtime/Systems/LocalToWorldSystem.cs
+++ b/Nerfed.Runtime/Systems/LocalToWorldSystem.cs
@@ -2,7 +2,6 @@
 using Nerfed.Runtime.Components;
 using Nerfed.Runtime.Util;
 using System.Numerics;
-using static System.Runtime.InteropServices.JavaScript.JSType;
 
 // TODO:
 // Explore if having a WorldTransform and LocalTransfom component each holding position, rotation, scale values and the matricies is useful.