add getter for Aabb3 directly (getBoundingBox) on ThermionAsset

thermion_dart/lib/src/filament/src/asset.dart

@@ -64,6 +64,13 @@ abstract class ThermionAsset {
   ///
   Future removeStencilHighlight();
 
+  ///
+  /// The dimensions of the bounding box for this asset.
+  /// This is independent of the boundingBoxAsset (which is used to visualize 
+  /// the bounding box in the scene); you do not need to call 
+  /// [createBoundingBoxAsset] before this method.
+  Future<Aabb3> getBoundingBox();
+
   ///
   /// The bounding box for this asset, as an actual renderable asset.
   /// Null by default; call [createBoundingBoxAsset] first to create.

thermion_dart/lib/src/viewer/src/ffi/src/background_image.dart

@@ -1,5 +1,5 @@
 import 'dart:typed_data';
-
+import 'package:vector_math/vector_math_64.dart' as v64;
 import 'package:animation_tools_dart/src/bone_animation_data.dart';
 import 'package:animation_tools_dart/src/morph_animation_data.dart';
 import 'package:thermion_dart/src/filament/src/layers.dart';
@@ -338,8 +338,8 @@ class BackgroundImage extends ThermionAsset {
   }
 
   @override
-  Future<MaterialInstance> getMaterialInstanceAt({ThermionEntity? entity, int index = 0}) {
-    // TODO: implement getMaterialInstanceAt
+  Future<MaterialInstance> getMaterialInstanceAt(
+      {ThermionEntity? entity, int index = 0}) {
     throw UnimplementedError();
   }
 
@@ -347,7 +347,10 @@ class BackgroundImage extends ThermionAsset {
 
   @override
   Future<ThermionAsset> createBoundingBoxAsset() {
-    // TODO: implement getBoundingBoxAsset
+    throw UnimplementedError();
+  }
+
+  Future<v64.Aabb3> getBoundingBox() {
     throw UnimplementedError();
   }
 }

thermion_dart/lib/src/viewer/src/ffi/src/ffi_asset.dart

@@ -246,8 +246,14 @@ class FFIAsset extends ThermionAsset {
     throw UnimplementedError();
   }
 
+  ///
+  ///
+  ///
   ThermionAsset? boundingBoxAsset;
 
+  ///
+  ///
+  ///
   Future<v64.Aabb3> getBoundingBox() async {
     final entities = <ThermionEntity>[];
     if (RenderableManager_isRenderable(app.renderableManager, entity)) {