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/c_api/TRenderableManager.cpp

@@ -0,0 +1,44 @@
+
+#include <filament/MaterialInstance.h>
+#include <filament/RenderableManager.h>
+#include <utils/Entity.h>
+
+#include "Log.hpp"
+#include "c_api/TRenderableManager.h"
+
+namespace thermion
+{
+
+    extern "C"
+    {
+        using namespace filament;
+        using namespace utils;
+
+        EMSCRIPTEN_KEEPALIVE void RenderableManager_setMaterialInstanceAt(TRenderableManager *tRenderableManager, EntityId entityId, int primitiveIndex, TMaterialInstance *tMaterialInstance)
+        {
+            auto *renderableManager = reinterpret_cast<filament::RenderableManager *>(tRenderableManager);
+            const auto &entity = utils::Entity::import(entityId);
+            auto renderableInstance = renderableManager->getInstance(entity);
+            auto materialInstance = reinterpret_cast<MaterialInstance *>(tMaterialInstance);
+            renderableManager->setMaterialInstanceAt(renderableInstance, primitiveIndex, materialInstance);
+        }
+
+        EMSCRIPTEN_KEEPALIVE TMaterialInstance *RenderableManager_getMaterialInstanceAt(TRenderableManager *tRenderableManager, EntityId entityId, int primitiveIndex) {
+            auto *renderableManager = reinterpret_cast<filament::RenderableManager *>(tRenderableManager);
+            const auto &entity = utils::Entity::import(entityId);
+            auto renderableInstance = renderableManager->getInstance(entity);
+            if(!renderableInstance.isValid()) {
+                return nullptr;
+            }
+            auto materialInstance = renderableManager->getMaterialInstanceAt(renderableInstance, primitiveIndex);
+            return reinterpret_cast<TMaterialInstance*>(materialInstance);
+        }
+
+        EMSCRIPTEN_KEEPALIVE void RenderableManager_setPriority(TRenderableManager *tRenderableManager, EntityId entityId, int priority) { 
+            auto *renderableManager = reinterpret_cast<filament::RenderableManager *>(tRenderableManager);
+            const auto &entity = utils::Entity::import(entityId);
+            auto renderableInstance = renderableManager->getInstance(entity);
+            renderableManager->setPriority(renderableInstance, priority);
+        }
+    }
+}