texture remapping on import to allow for storing in-project reference…

…s properly

UnityGLTF/Assets/UnityGLTF/Editor/Scripts/GLTFImporter.cs

@@ -94,6 +94,7 @@ private static void EnsureShadersAreLoaded()
 
         // TODO make internal and allow access for relevant assemblies
         public Material[] ImportedMaterials => m_Materials;
+        public Texture[] ImportedTextures => m_Textures;
 
         [Serializable]
         internal class ExtensionInfo
@@ -502,7 +503,7 @@ string GetUniqueName(string desiredName)
                         }
                         return matTextures;
                     }).Distinct().ToArray();
-                    
+
                     // texture asset remapping
                     foreach (var entry in texMaterialMap)
                     {

UnityGLTF/Assets/UnityGLTF/Editor/Scripts/ShaderGraph/MaterialEditorBridge.cs

@@ -48,6 +48,36 @@ private static void OnImmutableMaterialChanged(Material material)
 			exporter.SaveGLTFandBin(path, name);
 			AssetDatabase.ImportAsset(path);
 
+			// add texture remaps, so that the textures we just exported with stay valid.
+			// We want to always have default paths in the file, and remapping is done on the Unity side to a project specific path,
+			// to avoid breaking references all the time when paths change.
+			var exportedTextures = exporter.GetRoot().Textures;
+			var importedTextures = importer.ImportedTextures;
+			// If these don't match, we could only try by name... not ideal.
+			// They may not match due to different sampler settings etc.
+			if (exportedTextures.Count == importedTextures.Length)
+			{
+				for (int i = 0; i < exportedTextures.Count; i++)
+				{
+					var exported = exportedTextures[i];
+					var imported = importedTextures[i];
+					// TODO could we also use the imported texture definitions instead of the actual imported textures?
+					// Then we wouldn't need to create mock textures on import for all missing/remapped ones.
+					if (exported.Name != imported.name)
+					{
+						Debug.LogWarning($"Texture name mismatch: {exported.Name} != {imported.name}");
+					}
+
+					var sourceTextureForExportedTexture = exporter.GetSourceTextureForExportedTexture(exported);
+
+					// we should not remap if that is actually the same texture
+					if (imported == sourceTextureForExportedTexture) continue;
+
+					importer.AddRemap(new AssetImporter.SourceAssetIdentifier(imported), sourceTextureForExportedTexture);
+				}
+				importer.SaveAndReimport();
+			}
+
 			// TODO we should get rid of this, but without it currently the inspector doesn't repaint
 			// after importing a changed material, which can be confusing. Could be caching inside PBRGraphGUI
 			AssetDatabase.Refresh();

UnityGLTF/Assets/UnityGLTF/Runtime/Scripts/Loader/FileLoader.cs

@@ -60,7 +60,9 @@ public Stream LoadStream(string relativeFilePath)
 			{
 				if (relativeFilePath.ToLowerInvariant().EndsWith(".bin"))
 					throw new FileNotFoundException("Buffer file " + relativeFilePath + " not found in " + _rootDirectoryPath + ", complete path: " + pathToLoad, relativeFilePath);
-
+
+				// One exception here: we don't want to log an error if we're already knowing that the texture
+				// has been remapped on import - that's fine! A missing texture can be remapped to a valid one.
 				UnityEngine.Debug.LogError("Buffer file " + relativeFilePath + " not found in " + _rootDirectoryPath + ", complete path: " + pathToLoad);
 				return InvalidStream;
 			}

UnityGLTF/Assets/UnityGLTF/Runtime/Scripts/SceneExporter/ExporterMaterials.cs

@@ -929,5 +929,12 @@ private MaterialCommonConstant ExportCommonConstant(Material materialObj)
 
 			return constant;
 		}
+
+		// TODO make internal
+		public Texture GetSourceTextureForExportedTexture(GLTFTexture exported)
+		{
+			var textureIndex = _root.Textures.FindIndex(x => x == exported);
+			return _textures[textureIndex].Texture;
+		}
 	}
 }

UnityGLTF/Assets/UnityGLTF/Runtime/Scripts/SceneImporter/ImporterTextures.cs

@@ -168,13 +168,13 @@ protected virtual async Task ConstructUnityTexture(Stream stream, bool markGpuOn
 				return;
 			}
 #endif
-			Texture2D texture = new Texture2D(0, 0, TextureFormat.RGBA32, GenerateMipMapsForTextures, isLinear);
+			Texture2D texture = new Texture2D(4, 4, TextureFormat.RGBA32, GenerateMipMapsForTextures, isLinear);
 			texture.name = string.IsNullOrEmpty(image.Name) ? Path.GetFileNameWithoutExtension(image.Uri) : image.Name;
 
 			if (stream == FileLoader.InvalidStream)
 			{
-				// ignore
-				texture = null;
+				// ignore - we still need a valid texture so that we can properly remap
+				// texture = null;
 			}
 			else if (stream is MemoryStream)
 			{