Fix extension loading

ReFuel.Gltf/GltfMesh.cs

@@ -165,8 +165,14 @@ namespace ReFuel.Gltf
                 this.material.Id = index;
             }
 
-            // TODO: materials.
-            // TODO: morph targets.
+            if (element.TryGetProperty("targets", out JsonElement targetsElement))
+            {
+                foreach (JsonProperty property in materialElement.EnumerateObject())
+                {
+                    //TODO: targets
+                    //this.Targets.Add(weights);
+                }
+            }
 
             if (element.TryGetProperty("mode", out JsonElement modeElement))
             {

ReFuel.Gltf/GltfObject.cs

@@ -29,7 +29,7 @@ namespace ReFuel.Gltf
     {
         public abstract GltfObjectKind Kind { get; }
         public GltfDocument Document { get; protected set; }
-        public GltfCollection Extension { get; protected set; } = new GltfCollection();
+        public GltfCollection Extension { get; protected set; } = new GltfCollection(true);
         public GltfCollection Extras { get; protected set; } = new GltfCollection();
 
         protected GltfObject()
@@ -49,7 +49,7 @@ namespace ReFuel.Gltf
             {
                 Extras.Parse(extras);
             }
-            if (element.TryGetProperty("extension", out JsonElement extension))
+            if (element.TryGetProperty("extensions", out JsonElement extension))
             {
                 Extension.Parse(extension);
             }

ReFuel.Gltf/GltfSerializedExtensionProvider.cs

@@ -5,12 +5,10 @@ using System.Text.Json.Serialization;
 
 namespace ReFuel.Gltf
 {
-    public class GltfSerializedExtensionProvider<T> : IGltfExtensionProvider<T>
+    public class GltfSerializedExtensionProvider<T> : IGltfExtensionProvider
     {
         public string Name { get; }
 
-        public Type? DataType { get; } = typeof(T);
-
         public GltfSerializedExtensionProvider(string name)
         {
             Name = name;

ReFuel.Gltf/IGltfExtensionProvider.cs

@@ -6,15 +6,8 @@ namespace ReFuel.Gltf
     public interface IGltfExtensionProvider
     {
         string Name { get; }
-        Type? DataType { get; }
 
         object ParseExtensionObject(JsonElement element);
         void WriteExtensionObject(object obj, Utf8JsonWriter writer);
     }
-
-    public interface IGltfExtensionProvider<T> : IGltfExtensionProvider
-    {
-        T ParseExtension(JsonElement element);
-        void WriteExtension(T value, Utf8JsonWriter writer);
-    }
 }