add macOS implementation

example/lib/main.dart

@@ -39,7 +39,7 @@ class ExampleWidget extends StatefulWidget {
 }
 
 class _ExampleWidgetState extends State<ExampleWidget> {
-  late FilamentController _filamentController;
+  final _filamentController = FilamentController();
 
   FilamentEntity? _cube;
   FilamentEntity? _flightHelmet;
@@ -53,12 +53,6 @@ class _ExampleWidgetState extends State<ExampleWidget> {
   bool _rendering = false;
   int _framerate = 60;
 
-  @override
-  void initState() {
-    super.initState();
-    _filamentController = FilamentController();
-  }
-
   bool _initialized = false;
 
   bool _coneHidden = false;
@@ -75,14 +69,6 @@ class _ExampleWidgetState extends State<ExampleWidget> {
   @override
   Widget build(BuildContext context) {
     var children = [
-      _initialized
-          ? Container()
-          : _item(() async {
-              await _filamentController.initialize();
-              setState(() {
-                _initialized = true;
-              });
-            }, "initialize"),
       _item(() {
         _filamentController.render();
       }, "render"),
@@ -248,6 +234,10 @@ class _ExampleWidgetState extends State<ExampleWidget> {
           }, "play animation ${_animations!.indexOf(a)} (noreplace)")));
     }
 
+    children.add(_item(() {
+      _filamentController.setToneMapping(ToneMapper.LINEAR);
+    }, "Set tone mapping to linear"));
+
     return Padding(
         padding: EdgeInsets.only(top: 20, left: 20),
         child: Row(children: [