@@ -45,0 +46,4 @@
+  scene_delegate = std::make_unique<BlenderSceneDelegate>(
+    render_index.get(),
+    pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
+    BlenderSceneDelegate::EngineType::PREVIEW);

@@ -18,1 +15,3 @@
-      BlenderSceneDelegate::EngineType::PREVIEW);
+  scene_delegate->clear_data();
+
+  for (auto &prim : render_index->GetRprimIds()) {

@@ -19,2 +21,4 @@
 namespace blender::render::hydra {
 
+static double preview_engine_lifetime = 60.0;
+static PreviewEngine *preview_engine;

@@ -21,0 +26,4 @@
+double delete_preview_engine(uintptr_t uuid, void *user_data)
+{
+  if (preview_engine) {
+    preview_engine->stop_renderer();

@@ -21,0 +33,4 @@
+  }
+
+  return preview_engine_lifetime;
+}

@@ -117,0 +135,4 @@
+    if (BLI_timer_is_registered(1)) {
+      BLI_timer_unregister(1);
+    }
+    preview_engine->bl_engine = bl_engine;

@@ -477,4 +477,10 @@ pxr::VtValue BlenderSceneDelegate::GetLightParamValue(pxr::SdfPath const &id,
   return pxr::VtValue();
 }
 
+void BlenderSceneDelegate::clear_data()

@@ -21,0 +26,4 @@
+double delete_preview_engine(uintptr_t uuid, void *user_data)
+{
+  if (preview_engine) {
+    preview_engine->stop_renderer();

@@ -54,6 +54,12 @@ Engine::~Engine()
   render_delegate = nullptr;
   engine = nullptr;
   hgi = nullptr;
+  bl_engine = nullptr;

@@ -57,0 +57,4 @@
+  bl_engine = nullptr;
+}
+
+bool Engine::is_converged()

@@ -19,2 +20,4 @@
+
 namespace blender::render::hydra {
 
+static std::unique_ptr<PreviewEngine> preview_engine;

@@ -116,0 +124,4 @@
+    }
+    preview_engine->update_bl_engine(bl_engine);
+
+    CLOG_INFO(LOG_EN, 2, "Engine %016llx %s", engine, engine_type);

@@ -436,1 +436,4 @@
 
+void BlenderSceneDelegate::clear()
+{
+  for (auto it = materials.begin(); it != materials.end(); ++it) {

@@ -25,2 +25,4 @@
  private:
   std::map<pxr::TfToken, pxr::VtValue> data;
+  short p_type;
+  short p_shape;