feat: allow setting material instance directly on ThermionAsset

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

@@ -7,16 +7,50 @@ import 'package:thermion_dart/thermion_dart.dart';
 
 class FFIAsset extends ThermionAsset {
   
+  ///
+  ///
+  ///
   final Pointer<TSceneAsset> pointer;
+  
+  ///
+  ///
+  ///
   final Pointer<TSceneManager> sceneManager;
+  
+  ///
+  ///
+  ///
   Pointer<TRenderableManager> get renderableManager =>
       Engine_getRenderableManager(engine);
+  
+  ///
+  ///
+  ///
   final Pointer<TEngine> engine;
+  
+  ///
+  ///
+  ///
   FFIAsset? _highlight;
+  
+  ///
+  ///
+  ///
   final Pointer<TMaterialProvider> _unlitMaterialProvider;
+  
+  ///
+  ///
+  ///
   final bool isInstance;
 
+  ///
+  ///
+  ///
   late final ThermionEntity entity;
+  
+  ///
+  ///
+  ///
   final ThermionViewer viewer;
 
   FFIAsset(this.pointer, this.sceneManager, this.engine,
@@ -100,6 +134,9 @@ class FFIAsset extends ThermionAsset {
     return result;
   }
 
+  ///
+  ///
+  ///
   @override
   Future removeStencilHighlight() async {
     if (_highlight != null) {
@@ -111,6 +148,9 @@ class FFIAsset extends ThermionAsset {
     }
   }
 
+  ///
+  ///
+  ///
   @override
   Future setStencilHighlight(
       {double r = 1.0,
@@ -175,11 +215,17 @@ class FFIAsset extends ThermionAsset {
     SceneManager_addToScene(sceneManager, targetHighlightEntity);
   }
 
+  ///
+  ///
+  ///
   @override
   Future addToScene() async {
     SceneAsset_addToScene(pointer, SceneManager_getScene(sceneManager));
   }
 
+  ///
+  ///
+  ///
   @override
   Future removeFromScene() async {
     SceneManager_removeFromScene(sceneManager, entity);
@@ -194,14 +240,17 @@ class FFIAsset extends ThermionAsset {
     late ThermionEntity targetEntity;
     if (RenderableManager_isRenderable(renderableManager, entity)) {
       targetEntity = entity;
-    } else { 
+    } else {
       targetEntity = (await getChildEntities()).first;
     }
-    final aabb3 = SceneManager_getRenderableBoundingBox(sceneManager, targetEntity);
+    final aabb3 =
+        SceneManager_getRenderableBoundingBox(sceneManager, targetEntity);
     return aabb3;
   }
 
-
+  ///
+  ///
+  ///
   @override
   Future<void> setBoundingBoxVisibility(bool visible) async {
     if (boundingBoxAsset == null) {
@@ -293,4 +342,17 @@ class FFIAsset extends ThermionAsset {
       await boundingBoxAsset!.removeFromScene();
     }
   }
+
+  ///
+  ///
+  ///
+  @override
+  Future setMaterialInstanceAt(FFIMaterialInstance instance) async {
+    var childEntities = await getChildEntities();
+    final entities = <ThermionEntity>[entity, ...childEntities];
+    for (final entity in entities) {
+      RenderableManager_setMaterialInstanceAt(
+          Engine_getRenderableManager(engine), entity, 0, instance.pointer);
+    }
+  }
 }

thermion_dart/lib/src/viewer/src/shared_types/entities.dart

@@ -12,10 +12,21 @@ export 'light_options.dart';
 typedef ThermionEntity = int;
 
 abstract class ThermionAsset {
+  ///
+  ///
+  ///
   ThermionEntity get entity;
 
+  ///
+  ///
+  ///
   Future<List<ThermionEntity>> getChildEntities();
 
+  ///
+  ///
+  ///
+  Future setMaterialInstanceAt(covariant MaterialInstance instance);
+
   ///
   /// Renders an outline around [entity] with the given color.
   ///