fixes: limit allow editing of gltf materials to only pur materials and materiallibraries gltfs

Author: robertdorn83

Editor/Scripts/ShaderGraph/InternalShaderGraph/PBRGraphGUI.cs

@@ -594,6 +594,23 @@ public override void AssignNewShaderToMaterial(Material material, Shader oldShad
 		public delegate void OnImmutableMaterialChanged(Material material);
 		public static event OnImmutableMaterialChanged ImmutableMaterialChanged;
 
+		public delegate bool IsMaterialEditableCallback(Material material);
+		public static event IsMaterialEditableCallback IsMaterialEditable;
+
+		internal static bool GetIsMaterialEditable(Material material)
+		{
+			
+			try
+			{
+				return IsMaterialEditable?.Invoke(material) ?? false;
+			}
+			catch (Exception e)
+			{
+				Debug.LogException(e);
+				return false;
+			}
+		}
+		
 		internal static void InvokeMaterialChangedEvent(Material material)
 		{
 			try
@@ -639,9 +656,9 @@ internal static bool CanEdit(Material materialEditorTarget)
 		{
 			if (CanEditCache.TryGetValue(materialEditorTarget, out var canEdit))
 				return canEdit;
-
-			// we can only edit this material if it's from a .gltf file right now. We're caching this here to avoid having to re-parse the file
-			canEdit = AssetDatabase.GetAssetPath(materialEditorTarget).EndsWith(".gltf", StringComparison.OrdinalIgnoreCase);
+			
+			canEdit = PBRGraphGUI.GetIsMaterialEditable(materialEditorTarget);
+			
 			CanEditCache.Add(materialEditorTarget, canEdit);
 			return canEdit;
 		}

Editor/Scripts/ShaderGraph/MaterialEditorBridge.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -12,6 +13,28 @@ internal static class MaterialEditorBridge
 		private static void ConnectGltfExporterToPbrGraphGUI()
 		{
 			PBRGraphGUI.ImmutableMaterialChanged += OnImmutableMaterialChanged;
+			PBRGraphGUI.IsMaterialEditable += IsMaterialEditable;
+		}
+		
+		internal static bool IsMaterialEditable(Material material)
+		{
+			if (!material) return false;
+			if (!AssetDatabase.Contains(material)) return false;
+
+			var assetPath = AssetDatabase.GetAssetPath(material);
+			if (!assetPath.EndsWith(".gltf", StringComparison.OrdinalIgnoreCase))
+			{
+				// If the material is not part of a GLTF asset, we don't want to edit it.
+				return false;
+			}
+			
+			var mainAssetType = AssetDatabase.GetMainAssetTypeAtPath(assetPath);
+			if (mainAssetType != typeof(Material) && mainAssetType != typeof(MaterialLibrary))
+			{
+				return false;
+			}
+
+			return true;
 		}
 
 		internal static void OnImmutableMaterialChanged(Material material)