add test for create/destroy geometry instances

thermion_dart/test/instancing_tests.dart

@@ -4,6 +4,7 @@ import 'dart:math';
 import 'package:test/test.dart';
 import 'package:thermion_dart/src/filament/src/interface/asset.dart';
 import 'package:thermion_dart/src/filament/src/interface/filament_app.dart';
+import 'package:thermion_dart/src/utils/src/geometry.dart';
 import 'package:vector_math/vector_math_64.dart';
 import 'helpers.dart';
 
@@ -22,6 +23,32 @@ class PhysicsState {
 void main() async {
   final testHelper = TestHelper("instancing");
   await testHelper.setup();
+
+  test('create/destroy instance for geometry asset', () async {
+    await testHelper.withViewer((viewer) async {
+      final mi = await FilamentApp.instance!.createUbershaderMaterialInstance();
+      var asset = await viewer.createGeometry(GeometryHelper.cube(),
+          materialInstances: [mi], addToScene: true, keepData: true);
+
+      await testHelper.capture(viewer.view, "geometry_no_instance");
+      expect(await asset.getInstanceCount(), 0);
+
+      var instance = await asset.createInstance();
+
+      expect(await asset.getInstanceCount(), 1);
+
+      await viewer.addToScene(instance);
+      await instance.setTransform(Matrix4.translation(Vector3(1, 0, 0)));
+      await testHelper.capture(viewer.view, "geometry_with_instance");
+
+      await viewer.destroyAsset(instance);
+      await testHelper.capture(viewer.view, "geometry_instance_destroyed");
+
+      await viewer.destroyAssets();
+      await testHelper.capture(viewer.view, "geometry_asset_destroyed");
+    }, bg: kRed);
+  });
+
   test('gltf assets always create one instance', () async {
     await testHelper.withViewer((viewer) async {
       var asset =
@@ -167,8 +194,10 @@ void main() async {
             state.position.add(state.velocity * timeStep);
 
             // Queue the asynchronous transform update
-            transformUpdates.add(state.instance
+            transformUpdates.add(state.instance.setTransform(Matrix4.compose(
-                .setTransform(Matrix4.compose(state.position, Quaternion.identity(), Vector3.all(state.scale))));
+                state.position,
+                Quaternion.identity(),
+                Vector3.all(state.scale))));
           }
         }
         // Wait for all instance transforms in this step to complete
@@ -214,6 +243,6 @@ void main() async {
 
       // Optional: Capture one final frame after simulation ends
       await testHelper.capture(viewer.view, "capture_physics_orbit_final");
-    }, viewportDimensions: (width:1024, height:1024)); // End withViewer
+    }, viewportDimensions: (width: 1024, height: 1024)); // End withViewer
   });
 }