feature!:

This is a breaking change needed to fully implement instancing and stencil highlighting.

Previously, users would work directly with entities (on the Dart side, ThermionEntity), e.g.

final entity = await viewer.loadGlb("some.glb");

However, Filament "entities" are a lower-level abstraction.

Loading a glTF file, for example, inserts multiple entities into the scene.

For example, each mesh, light, and camera within a glTF asset will be assigned an entity. A top-level (non-renderable) entity will also be created for the glTF asset, which can be used to transform the entire hierarchy.

"Asset" is a better representation for loading/inserting objects into the scene; think of this as a bundle of entities.

Unless you need to work directly with transforms, instancing, materials and renderables, you can work directly with ThermionAsset.

thermion_dart/native/src/scene/GltfSceneAsset.cpp

@@ -0,0 +1,61 @@
+
+#include "scene/GltfSceneAsset.hpp"
+#include "scene/GltfSceneAssetInstance.hpp"
+#include "gltfio/FilamentInstance.h"
+#include "Log.hpp"
+namespace thermion
+{
+
+    GltfSceneAsset::~GltfSceneAsset()
+    {
+        _instances.clear();
+        _asset->releaseSourceData();
+        _assetLoader->destroyAsset(_asset);    
+    }
+
+    SceneAsset *GltfSceneAsset::createInstance(MaterialInstance **materialInstances, size_t materialInstanceCount)
+    {
+        auto instanceNumber = _instances.size();
+        
+        if (instanceNumber > _asset->getAssetInstanceCount() - 1)
+        {
+            Log("No instances available for reuse. When loading the asset, you must pre-allocate the number of instances you wish to make available for use. Try increasing this number.");
+            return std::nullptr_t();
+        }
+        Log("Creating instance %d", instanceNumber);
+        auto instance = _asset->getAssetInstances()[instanceNumber];
+        instance->recomputeBoundingBoxes();
+        instance->getAnimator()->updateBoneMatrices();
+
+        auto& rm = _engine->getRenderableManager();
+
+        if(materialInstanceCount > 0) {
+            for(int i = 0; i < instance->getEntityCount(); i++) {
+                auto renderableInstance = rm.getInstance(instance->getEntities()[i]);
+                if(!renderableInstance.isValid()) {
+                    Log("Instance is not renderable");
+                } else {
+                    for(int i = 0; i < materialInstanceCount; i++) {
+                        rm.setMaterialInstanceAt(renderableInstance, i, materialInstances[i]);
+                    }
+                }                
+            }
+        }
+
+        std::unique_ptr<GltfSceneAssetInstance> sceneAssetInstance = std::make_unique<GltfSceneAssetInstance>(
+            instance,
+            _engine,
+            materialInstances, 
+            materialInstanceCount
+        );
+
+        auto *raw = sceneAssetInstance.get();
+
+        _instances.push_back(std::move(sceneAssetInstance));
+        return raw;
+    }
+
+    
+
+
+}