update example project

example/lib/main.dart

@@ -31,10 +31,7 @@ class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
   Widget build(BuildContext context) {
     return MaterialApp(
         // showPerformanceOverlay: true,
-        home: Scaffold(
+        home: Scaffold(body: ExampleWidget()));
-      body: 
-      ExampleWidget()
-    ));
   }
 }
 
@@ -60,7 +57,7 @@ class _ExampleWidgetState extends State<ExampleWidget> {
   bool _loop = false;
   EdgeInsets _viewportMargin = EdgeInsets.zero;
 
-  bool _readyForScene = false;
+  bool _hasViewer = false;
 
   bool _rendering = false;
   int _framerate = 60;
@@ -69,13 +66,10 @@ class _ExampleWidgetState extends State<ExampleWidget> {
   bool _coneHidden = false;
   bool _frustumCulling = true;
 
-  StreamSubscription? _hasViewerListener;
-
   @override
   void dispose() {
     super.dispose();
     _pickResultListener?.cancel();
-    _hasViewerListener?.cancel();
   }
 
   Widget _item(void Function() onTap, String text) {
@@ -99,12 +93,6 @@ class _ExampleWidgetState extends State<ExampleWidget> {
         picked = _filamentController!.getNameForEntity(entityId!);
       });
     });
-    _hasViewerListener =
-        _filamentController!.hasViewer.listen((bool hasViewer) {
-      setState(() {
-        _readyForScene = hasViewer;
-      });
-    });
   }
 
   @override
@@ -115,7 +103,7 @@ class _ExampleWidgetState extends State<ExampleWidget> {
       children.addAll([
         _item(() {
           _createController();
-        }, "create viewer (default ubershader)"),
+        }, "create FilamentController (default ubershader)"),
         _item(() {
           _createController(
               uberArchivePath: Platform.isWindows
@@ -125,15 +113,26 @@ class _ExampleWidgetState extends State<ExampleWidget> {
                       : Platform.isIOS
                           ? "assets/lit_opaque_43.uberz"
                           : "assets/lit_opaque_43_gles.uberz");
-        }, "create viewer (custom ubershader - lit opaque only)"),
+        }, "create FilamentController (custom ubershader - lit opaque only)"),
       ]);
-    }
+    } else {
-
+      if (!_hasViewer) {
-    if (_readyForScene) {
+        children.addAll([
+          _item(() {
+            _filamentController!.createViewer();
+            setState(() {
+              _hasViewer = true;
+            });
+          }, "create FilamentViewer")
+        ]);
+      } else {
         children.addAll([
           _item(() {
             _filamentController!.destroy();
             _filamentController = null;
+            setState(() {
+              _hasViewer = true;
+            });
           }, "destroy viewer/texture"),
           _item(() {
             _filamentController!.render();
@@ -190,7 +189,8 @@ class _ExampleWidgetState extends State<ExampleWidget> {
           _item(() async {
             _shapes =
                 await _filamentController!.loadGlb('assets/shapes/shapes.glb');
-          _animations = await _filamentController!.getAnimationNames(_shapes!);
+            _animations =
+                await _filamentController!.getAnimationNames(_shapes!);
             setState(() {});
           }, 'load shapes GLB'),
           _item(() async {
@@ -266,18 +266,20 @@ class _ExampleWidgetState extends State<ExampleWidget> {
                 });
           }, "show morph target names for Cylinder"),
           _item(() {
-          _filamentController!
+            _filamentController!.setMorphTargetWeights(
-              .setMorphTargetWeights(_shapes!, "Cylinder", List.filled(4, 1.0));
+                _shapes!, "Cylinder", List.filled(4, 1.0));
           }, "set Cylinder morph weights to 1"),
           _item(() {
-          _filamentController!
+            _filamentController!.setMorphTargetWeights(
-              .setMorphTargetWeights(_shapes!, "Cylinder", List.filled(4, 0.0));
+                _shapes!, "Cylinder", List.filled(4, 0.0));
           }, "set Cylinder morph weights to 0.0"),
           _item(() async {
             var morphs = await _filamentController!
                 .getMorphTargetNames(_shapes!, "Cylinder");
             final animation = AnimationBuilder(
-                  availableMorphs: morphs, framerate: 30, meshName: "Cylinder")
+                    availableMorphs: morphs,
+                    framerate: 30,
+                    meshName: "Cylinder")
                 .setDuration(4)
                 .setMorphTargets(["Key 1", "Key 2"])
                 .interpolateMorphWeights(0, 4, 0, 1)
@@ -288,7 +290,9 @@ class _ExampleWidgetState extends State<ExampleWidget> {
             var morphs = await _filamentController!
                 .getMorphTargetNames(_shapes!, "Cylinder");
             final animation = AnimationBuilder(
-                  availableMorphs: morphs, framerate: 30, meshName: "Cylinder")
+                    availableMorphs: morphs,
+                    framerate: 30,
+                    meshName: "Cylinder")
                 .setDuration(4)
                 .setMorphTargets(["Key 3", "Key 4"])
                 .interpolateMorphWeights(0, 4, 0, 1)
@@ -296,8 +300,8 @@ class _ExampleWidgetState extends State<ExampleWidget> {
             _filamentController!.setMorphAnimationData(_shapes!, animation);
           }, "animate cylinder morph weights #3 and #4"),
           _item(() async {
-          var morphs =
+            var morphs = await _filamentController!
-              await _filamentController!.getMorphTargetNames(_shapes!, "Cube");
+                .getMorphTargetNames(_shapes!, "Cube");
             final animation = AnimationBuilder(
                     availableMorphs: morphs, framerate: 30, meshName: "Cube")
                 .setDuration(4)
@@ -353,6 +357,7 @@ class _ExampleWidgetState extends State<ExampleWidget> {
           _filamentController!.setViewFrustumCulling(_frustumCulling);
         }, "${_frustumCulling ? "Disable" : "Enable"} frustum culling"));
       }
+    }
     return Stack(children: [
       _filamentController != null
           ? Positioned.fill(