Add **Behavior Tree** asset type and editing

Source/Editor/Surface/BehaviorTreeSurface.cs

@@ -0,0 +1,158 @@
+// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using FlaxEditor.Scripting;
+using FlaxEditor.Surface.ContextMenu;
+using FlaxEditor.Surface.Elements;
+using FlaxEngine;
+using FlaxEngine.GUI;
+
+namespace FlaxEditor.Surface
+{
+    /// <summary>
+    /// The Visject Surface implementation for the Behavior Tree graphs.
+    /// </summary>
+    /// <seealso cref="VisjectSurface" />
+    [HideInEditor]
+    public class BehaviorTreeSurface : VisjectSurface
+    {
+        private static NodesCache _nodesCache = new NodesCache(IterateNodesCache);
+
+        /// <inheritdoc />
+        public BehaviorTreeSurface(IVisjectSurfaceOwner owner, Action onSave, FlaxEditor.Undo undo)
+        : base(owner, onSave, undo, CreateStyle())
+        {
+        }
+
+        private static SurfaceStyle CreateStyle()
+        {
+            var editor = Editor.Instance;
+            var style = SurfaceStyle.CreateStyleHandler(editor);
+            style.DrawBox = DrawBox;
+            style.DrawConnection = DrawConnection;
+            return style;
+        }
+
+        private static void DrawBox(Box box)
+        {
+            var rect = new Rectangle(Float2.Zero, box.Size);
+            const float minBoxSize = 5.0f;
+            if (rect.Size.LengthSquared < minBoxSize * minBoxSize)
+                return;
+
+            var style = FlaxEngine.GUI.Style.Current;
+            var color = style.LightBackground;
+            if (box.IsMouseOver)
+                color *= 1.2f;
+            Render2D.FillRectangle(rect, color);
+        }
+
+        private static void DrawConnection(Float2 start, Float2 end, Color color, float thickness)
+        {
+            Archetypes.Animation.StateMachineStateBase.DrawConnection(ref start, ref end, ref color);
+        }
+
+        private void OnActiveContextMenuVisibleChanged(Control activeCM)
+        {
+            _nodesCache.Wait();
+        }
+
+        private static void IterateNodesCache(ScriptType scriptType, Dictionary<KeyValuePair<string, ushort>, GroupArchetype> cache, int version)
+        {
+            // Filter by BT node types only
+            if (!new ScriptType(typeof(BehaviorTreeNode)).IsAssignableFrom(scriptType))
+                return;
+
+            // Skip in-built types
+            if (scriptType == typeof(BehaviorTreeNode) ||
+                scriptType == typeof(BehaviorTreeCompoundNode) ||
+                scriptType == typeof(BehaviorTreeRootNode))
+                return;
+
+            // Create group archetype
+            var groupKey = new KeyValuePair<string, ushort>("Behavior Tree", 19);
+            if (!cache.TryGetValue(groupKey, out var group))
+            {
+                group = new GroupArchetype
+                {
+                    GroupID = groupKey.Value,
+                    Name = groupKey.Key,
+                    Color = new Color(70, 220, 181),
+                    Tag = version,
+                    Archetypes = new List<NodeArchetype>(),
+                };
+                cache.Add(groupKey, group);
+            }
+
+            // Create node archetype
+            var node = (NodeArchetype)Archetypes.BehaviorTree.Nodes[0].Clone();
+            node.DefaultValues[0] = scriptType.TypeName;
+            node.Flags &= ~NodeFlags.NoSpawnViaGUI;
+            node.Title = Archetypes.BehaviorTree.Node.GetTitle(scriptType);
+            node.Description = Editor.Instance.CodeDocs.GetTooltip(scriptType);
+            ((IList<NodeArchetype>)group.Archetypes).Add(node);
+        }
+
+        /// <inheritdoc />
+        protected override void OnShowPrimaryMenu(VisjectCM activeCM, Float2 location, Box startBox)
+        {
+            activeCM.ShowExpanded = true;
+            _nodesCache.Get(activeCM);
+
+            base.OnShowPrimaryMenu(activeCM, location, startBox);
+
+            activeCM.VisibleChanged += OnActiveContextMenuVisibleChanged;
+        }
+
+        /// <inheritdoc />
+        public override string GetTypeName(ScriptType type)
+        {
+            if (type == ScriptType.Void)
+                return string.Empty; // Remove `Void` tooltip from connection areas
+            return base.GetTypeName(type);
+        }
+
+        /// <inheritdoc />
+        public override bool Load()
+        {
+            if (base.Load())
+                return true;
+
+            // Ensure to have Root node created (UI blocks spawning of it)
+            if (RootContext.FindNode(19, 2) == null)
+            {
+                RootContext.SpawnNode(19, 2, Float2.Zero);
+            }
+
+            return false;
+        }
+
+        /// <inheritdoc />
+        public override bool CanUseNodeType(GroupArchetype groupArchetype, NodeArchetype nodeArchetype)
+        {
+            // Comments
+            if (groupArchetype.GroupID == 7 && nodeArchetype.TypeID == 11)
+                return true;
+
+            // Single root node
+            if (groupArchetype.GroupID == 19 && nodeArchetype.TypeID == 2 && RootContext.FindNode(19, 2) != null)
+                return false;
+
+            // Behavior Tree nodes only
+            return (nodeArchetype.Flags & NodeFlags.BehaviorTreeGraph) != 0 &&
+                   groupArchetype.GroupID == 19 &&
+                   base.CanUseNodeType(groupArchetype, nodeArchetype);
+        }
+
+        /// <inheritdoc />
+        public override void OnDestroy()
+        {
+            if (IsDisposing)
+                return;
+            _nodesCache.Wait();
+
+            base.OnDestroy();
+        }
+    }
+}