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/TGizmo.cpp

@@ -0,0 +1,41 @@
+#include <filament/View.h>
+#include <filament/Engine.h>
+#include <filament/Scene.h>
+
+#include "c_api/TGizmo.h"
+#include "scene/Gizmo.hpp"
+#include "Log.hpp"
+
+#ifdef __cplusplus
+namespace thermion
+{
+    extern "C"
+    {
+        using namespace filament;
+#endif
+
+        EMSCRIPTEN_KEEPALIVE void Gizmo_pick(TGizmo *tGizmo, uint32_t x, uint32_t y, GizmoPickCallback callback)
+        {
+            auto *gizmo = reinterpret_cast<Gizmo *>(tGizmo);
+            gizmo->pick(x, y, reinterpret_cast<Gizmo::GizmoPickCallback>(callback));
+        }
+
+        EMSCRIPTEN_KEEPALIVE void Gizmo_highlight(TGizmo *tGizmo, TGizmoAxis tAxis)
+        {
+            auto *gizmo = reinterpret_cast<Gizmo *>(tGizmo);
+            auto axis = static_cast<Gizmo::Axis>(tAxis);
+            gizmo->highlight(axis);
+        }
+
+        EMSCRIPTEN_KEEPALIVE void Gizmo_unhighlight(TGizmo *tGizmo)
+        {
+            auto *gizmo = reinterpret_cast<Gizmo *>(tGizmo);
+            gizmo->unhighlight(Gizmo::Axis::X);
+            gizmo->unhighlight(Gizmo::Axis::Y);
+            gizmo->unhighlight(Gizmo::Axis::Z);
+        }
+
+#ifdef __cplusplus
+    }
+}
+#endif