b/149241458: Don't try to open null gltf buffer URIs

Manually cherry-picked from go/tbcl/118853

Change-Id: Id000b015b9ea3122d41154be31c6158428546338

UnitySDK/Assets/TiltBrush/Scripts/Editor/Glb1Importer.cs

@@ -39,12 +39,11 @@ public class Glb1Importer : ScriptedImporter {
   };
 
   public override void OnImportAsset(AssetImportContext ctx) {
-    StringReader gltfStream = new StringReader(GlbParser.GetJsonChunkAsString(ctx.assetPath));
     IUriLoader loader = new BufferedStreamLoader(
         ctx.assetPath, Path.GetDirectoryName(ctx.assetPath));
 
     ImportGltf.GltfImportResult result = ImportGltf.Import(
-        GltfSchemaVersion.GLTF1, gltfStream, loader, null, kOptions);
+        ctx.assetPath, loader, null, kOptions);
 
     // The "identifier" param passed here is supposed to be:
     // - Unique to this asset

UnitySDK/Assets/TiltBrush/Scripts/Editor/Glb2Importer.cs

@@ -39,12 +39,11 @@ public class Glb2Importer : ScriptedImporter {
   };
 
   public override void OnImportAsset(AssetImportContext ctx) {
-    StringReader gltfStream = new StringReader(GlbParser.GetJsonChunkAsString(ctx.assetPath));
     IUriLoader loader = new BufferedStreamLoader(
         ctx.assetPath, Path.GetDirectoryName(ctx.assetPath));
 
     ImportGltf.GltfImportResult result = ImportGltf.Import(
-        GltfSchemaVersion.GLTF2, gltfStream, loader, null, kOptions);
+        ctx.assetPath, loader, null, kOptions);
 
     // The "identifier" param passed here is supposed to be:
     // - Unique to this asset

UnitySDK/Assets/TiltBrush/Scripts/Gltf/Gltf1Schema.cs

@@ -86,7 +86,7 @@ protected override void Dispose(bool disposing) {
   }
 
   /// Map glTFid values (ie, string names) names to the objects they refer to
-  public override void Dereference(IUriLoader uriLoader = null) {
+  public override void Dereference(bool isGlb, IUriLoader uriLoader = null) {
     // "dereference" all the names
     scenePtr = scenes[scene];
     foreach (var pair in buffers) {

UnitySDK/Assets/TiltBrush/Scripts/Gltf/Gltf2Schema.cs

@@ -87,15 +87,19 @@ protected override void Dispose(bool disposing) {
   }
 
   /// Map gltfIndex values (ie, int indices) names to the objects they refer to
-  public override void Dereference(IUriLoader uriLoader = null) {
+  public override void Dereference(bool isGlb, IUriLoader uriLoader = null) {
     // "dereference" all the indices
     scenePtr = scenes[scene];
     for (int i = 0; i < buffers.Count; i++) {
       Gltf2Buffer buffer = buffers[i];
       buffer.gltfIndex = i;
+      if (buffer.uri == null && !(i == 0 && isGlb)) {
+        Debug.LogErrorFormat("Buffer {0} isGlb {1} has null uri", i, isGlb);
+        // leave the data buffer null
+        return;
+      }
+
       if (uriLoader != null) {
-        // Only id 0 may lack a URI; this indicates that it is the binary chunk.
-        Debug.Assert(! (i != 0 && buffer.uri == null));
         buffer.data = uriLoader.Load(buffer.uri);
       }
     }

UnitySDK/Assets/TiltBrush/Scripts/Gltf/GltfSchemaCommon.cs

@@ -158,7 +158,7 @@ public abstract class GltfRootBase : IDisposable {
   public abstract IEnumerable<GltfMaterialBase> Materials { get; }
   public abstract IEnumerable<GltfMeshBase> Meshes { get; }
 
-  public abstract void Dereference(IUriLoader uriLoader = null);
+  public abstract void Dereference(bool isGlb, IUriLoader uriLoader = null);
 
   // Disposable pattern, with Dispose(void) and Dispose(bool), as recommended by:
   // https://docs.microsoft.com/en-us/dotnet/api/system.idisposable

UnitySDK/Assets/TiltBrush/Scripts/Gltf/ImportGltf.cs

@@ -109,6 +109,44 @@ public void Dispose() {
     }
   }
 
+  public class GltfFileInfo : IDisposable {
+    public string Path { get; private set; }
+    public GltfSchemaVersion Version { get; private set; }
+    public bool IsGlb { get; private set; }
+    public TextReader Reader { get; private set; }
+
+    public GltfFileInfo(string path) {
+      Path = path;
+      if (GlbParser.GetGlbVersion(path) is uint glbFormatVersion) {
+        IsGlb = true;
+        Version = (glbFormatVersion == 1 ? GltfSchemaVersion.GLTF1 : GltfSchemaVersion.GLTF2);
+        Reader = new StringReader(GlbParser.GetJsonChunkAsString(path));
+      } else {
+        IsGlb = false;
+        string json = File.ReadAllText(path);
+        var gltf1Or2 = JsonConvert.DeserializeObject<Gltf1Or2>(json);
+        var versionString = gltf1Or2?.asset?.version ?? "2";  // default to 2, I guess?
+        Version = versionString.StartsWith("1") ? GltfSchemaVersion.GLTF1 : GltfSchemaVersion.GLTF2;
+        Reader = new StringReader(json);
+      }
+    }
+
+    public void Dispose() {
+      if (Reader != null) {
+        Reader.Dispose();
+      }
+    }
+  }
+
+  // Used only by GetVersionAndReader. The layout of a gltf file changes significantly
+  // between gltf v1 and v2, but thankfully the location of the version info didn't change.
+  #pragma warning disable 0649
+  [Serializable]
+  private class Gltf1Or2 {
+    public GltfAsset asset;
+  }
+  #pragma warning restore 0649
+
   /// <summary>
   /// Import a gltf model.
   /// If you would like to perform some of the work off the main thread, use
@@ -122,10 +160,10 @@ public void Dispose() {
   /// <seealso cref="ImportGltf.BeginImport" />
   /// <seealso cref="ImportGltf.EndImport" />
   public static GltfImportResult Import(
-      GltfSchemaVersion gltfVersion, TextReader gltfStream, IUriLoader uriLoader,
+      string gltfOrGlbPath, IUriLoader uriLoader,
       IImportMaterialCollector materialCollector,
       GltfImportOptions options) {
-    using (var state = BeginImport(gltfVersion, gltfStream, uriLoader, options)) {
+    using (var state = BeginImport(gltfOrGlbPath, uriLoader, options)) {
       IEnumerable<Null> meshCreator;
       GltfImportResult result = EndImport(state, uriLoader, materialCollector, out meshCreator);
       foreach (var unused in meshCreator) {
@@ -204,17 +242,15 @@ private static void CheckCompatibility(
   /// </summary>
   /// <returns>An object which should be passed to <seealso cref="ImportGltf.EndImport"/> and then disposed</returns>
   public static ImportState BeginImport(
-      GltfSchemaVersion gltfVersion, TextReader stream, IUriLoader uriLoader,
-      GltfImportOptions options) {
-    if (stream == null) { throw new ArgumentNullException("stream"); }
+      string gltfOrGlbPath, IUriLoader uriLoader, GltfImportOptions options) {
     if (uriLoader == null) { throw new ArgumentNullException("uriLoader"); }
-
     SanityCheckImportOptions(options);
 
-    using (var reader = new JsonTextReader(stream)) {
-      var root = DeserializeGltfRoot(gltfVersion, reader);
+    using (var info = new GltfFileInfo(gltfOrGlbPath))
+    using (var reader = new JsonTextReader(info.Reader)) {
+      var root = DeserializeGltfRoot(info.Version, reader);
       if (root == null) { throw new NullReferenceException("root"); }
-      root.Dereference(uriLoader);
+      root.Dereference(info.IsGlb, uriLoader);
 
       // Convert attribute names to the ones we expect.
       // This may eg overwrite TEXCOORD_0 with _TB_UNITY_TEXCOORD_0 (which will contain more data)