add LdtkFieldInstance and LdtkEntityMap classes; update LdtkSceneBuilder to support entity mapping

addons/csharp_ldtk_importer/LdtkSceneBuilder.cs

@@ -1,4 +1,6 @@
+using System;
 using System.Linq;
+using System.Text.Json;
 using CSharpLdtkImporter.Models;
 using Godot;
 
@@ -8,12 +10,14 @@ public class LdtkSceneBuilder
 {
     private readonly LdtkData _ldtkData;
     private readonly string _basePath;
+    private readonly LdtkEntityMap _entityMap;
     private readonly Godot.Collections.Dictionary<int, TileSet> _tileSetCache = new();
 
-    public LdtkSceneBuilder(LdtkData ldtkData, string sourceFile)
+    public LdtkSceneBuilder(LdtkData ldtkData, string sourceFile, LdtkEntityMap entityMap)
     {
         _ldtkData = ldtkData;
         _basePath = sourceFile.GetBaseDir();
+        _entityMap = entityMap;
     }
 
     public Node2D BuildLdtkProjectRoot()
@@ -94,17 +98,57 @@ public class LdtkSceneBuilder
     private Node2D BuildEntityLayer(LdtkLayerInstance layer)
     {
         var entityLayerRoot = new Node2D { Name = layer.Identifier };
+        
         foreach (var entity in layer.EntityInstances)
         {
-            var marker = new Marker2D
+            Node2D instance = null;
+            
+            GD.Print($"EntityMap keys: {string.Join(", ", _entityMap?.EntitySceneMap.Keys ?? Array.Empty<string>())}");
+            GD.Print($"Entity Identifier: {entity.Identifier}");
+            GD.Print($"Is Entity Mapped: {_entityMap?.EntitySceneMap.ContainsKey(entity.Identifier)}");
+
+            if (_entityMap?.EntitySceneMap.TryGetValue(entity.Identifier, out var packedScene) == true &&
+                packedScene != null)
             {
-                Name = entity.Identifier,
-                Position = new Vector2(entity.Px[0], entity.Px[1])
-            };
-            entityLayerRoot.AddChild(marker);
+                GD.Print($"Instantiating entity '{entity.Identifier}' from mapped scene.");
+                instance = packedScene.Instantiate<Node2D>();
+            }
+            else
+            {
+                GD.Print($"Defaulting to Marker2D for unmapped entity '{entity.Identifier}'.");
+                instance = new Marker2D();
+            }
+            
+            instance.Name = entity.Identifier;
+            instance.Position = new Vector2(entity.Px[0], entity.Px[1]);
+
+            foreach (var field in entity.FieldInstances)
+            {
+                instance.SetMeta(field.Identifier, ConvertJsonElementToVariant(field.Value));
+            }
+            
+            entityLayerRoot.AddChild(instance);
         }
+        
         return entityLayerRoot;
     }
+
+    private static Variant ConvertJsonElementToVariant(JsonElement element)
+    {
+        return element.ValueKind switch
+        {
+            JsonValueKind.String => element.GetString(),
+            JsonValueKind.Number => element.GetDouble(),
+            JsonValueKind.True => true,
+            JsonValueKind.False => false,
+            JsonValueKind.Null => default,
+            // For LDTK points (which are objects) or arrays, we can serialize them back to a JSON string.
+            // A more advanced implementation could convert these to Vector2 or Array types.
+            JsonValueKind.Object => Json.Stringify(Json.ParseString(element.GetRawText())),
+            JsonValueKind.Array => Json.Stringify(Json.ParseString(element.GetRawText())),
+            _ => default
+        };
+    }
     
     private TileSet GetOrCreateTileSet(int tilesetDefUid)
     {