source/blender/render/hydra/engine.cc

@@ -42,11 +42,6 @@ Engine::Engine(RenderEngine *bl_engine, const std::string &delegate_id) : bl_eng
   }
 
   engine = std::make_unique<pxr::HdEngine>();
-
-  scene_delegate = std::make_unique<BlenderSceneDelegate>(
-    render_index.get(),
-    pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
-    BlenderSceneDelegate::EngineType::PREVIEW);
 }
 
 Engine::~Engine()
@@ -62,6 +57,11 @@ Engine::~Engine()
   bl_engine = nullptr;
 }
 
+bool Engine::is_converged()
+{
+  return render_task_delegate->is_converged();
+}
+
 float Engine::renderer_percent_done()
 {
   pxr::VtDictionary render_stats = render_delegate->GetRenderStats();

source/blender/render/hydra/engine.h

@@ -34,14 +34,14 @@ class Engine {
                     bContext *context,
                     pxr::HdRenderSettingsMap &render_settings) = 0;
   virtual void render(Depsgraph *depsgraph) = 0;
-
+  bool is_converged();
- public:
-  RenderEngine *bl_engine;
 
  protected:
   float renderer_percent_done();
 
  protected:
+  RenderEngine *bl_engine;
+
   pxr::HdPluginRenderDelegateUniqueHandle render_delegate;
   std::unique_ptr<pxr::HdRenderIndex> render_index;
   std::unique_ptr<BlenderSceneDelegate> scene_delegate;

source/blender/render/hydra/final_engine.cc

@@ -16,6 +16,10 @@ void FinalEngine::sync(Depsgraph *depsgraph,
                        bContext *context,
                        pxr::HdRenderSettingsMap &render_settings)
 {
+  scene_delegate = std::make_unique<BlenderSceneDelegate>(
+      render_index.get(),
+      pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
+      BlenderSceneDelegate::EngineType::FINAL);
   scene_delegate->populate(depsgraph, context);
 
   for (auto const &setting : render_settings) {

source/blender/render/hydra/preview_engine.cc

@@ -12,13 +12,13 @@ void PreviewEngine::sync(Depsgraph *depsgraph,
                          bContext *context,
                          pxr::HdRenderSettingsMap &render_settings)
 {
-  scene_delegate->clear_data();
+  if (!scene_delegate) {
-
+    scene_delegate = std::make_unique<BlenderSceneDelegate>(
-  for (auto &prim : render_index->GetRprimIds()) {
+        render_index.get(),
-    render_index->RemoveRprim(prim);
+        pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
-    render_index->RemoveInstancer(prim);
+        BlenderSceneDelegate::EngineType::PREVIEW);
   }
-
+  scene_delegate->clear();
   scene_delegate->populate(depsgraph, context);
 
   for (auto const &setting : render_settings) {
@@ -73,11 +73,21 @@ void PreviewEngine::render(Depsgraph *depsgraph)
   update_render_result(layer_name, res[0], res[1], pixels);
 }
 
-void PreviewEngine::stop_renderer()
+void PreviewEngine::update_bl_engine(RenderEngine *bl_engine)
 {
-  if (render_delegate) {
+  this->bl_engine = bl_engine;
-    render_delegate->Stop();
 }
+
+double PreviewEngine::delete_preview_engine(uintptr_t uuid, void *user_data)
+{
+  std::unique_ptr<PreviewEngine> *preview_engine = static_cast<std::unique_ptr<PreviewEngine>*>(user_data);
+  if (preview_engine && preview_engine->get()->is_converged()) {
+    CLOG_INFO(LOG_EN, 1, "Delete preview engine");
+    preview_engine->reset();
+    return -1;
+  }
+
+  return preview_engine_lifetime;
 }
 
 void PreviewEngine::update_render_result(const std::string &layer_name,

source/blender/render/hydra/preview_engine.h

@@ -14,7 +14,8 @@ class PreviewEngine : public FinalEngine {
             bContext *context,
             pxr::HdRenderSettingsMap &render_settings) override;
   void render(Depsgraph *depsgraph) override;
-  void stop_renderer();
+  void update_bl_engine(RenderEngine *bl_engine);
+  static double delete_preview_engine(uintptr_t uuid, void *user_data);
 
  protected:
   void update_render_result(const std::string &layer_name,
@@ -22,6 +23,9 @@ class PreviewEngine : public FinalEngine {
                             int height,
                             std::vector<float> &pixels);
 
+ public:
+  static inline double preview_engine_lifetime = 180.0;
+
  protected:
   pxr::HdRenderSettingsMap render_settings;
 };

source/blender/render/hydra/python.cc

@@ -20,20 +20,7 @@
 
 namespace blender::render::hydra {
 
-static double preview_engine_lifetime = 60.0;
+static std::unique_ptr<PreviewEngine> preview_engine;
-static PreviewEngine *preview_engine;
-
-double delete_preview_engine(uintptr_t uuid, void *user_data)
-{
-  if (preview_engine) {
-    preview_engine->stop_renderer();
-    delete preview_engine;
-    preview_engine = nullptr;
-    return -1;
-  }
-
-  return preview_engine_lifetime;
-}
 
 static PyObject *init_func(PyObject * /*self*/, PyObject *args)
 {
@@ -130,15 +117,15 @@ static PyObject *engine_create_func(PyObject * /*self*/, PyObject *args)
   }
   else if (STREQ(engine_type, "PREVIEW")) {
     if (!preview_engine) {
-      preview_engine = new PreviewEngine(bl_engine, render_delegate_id);
+      preview_engine = std::make_unique<PreviewEngine>(bl_engine, render_delegate_id);
     }
     if (BLI_timer_is_registered(1)) {
       BLI_timer_unregister(1);
     }
-    preview_engine->bl_engine = bl_engine;
+    preview_engine->update_bl_engine(bl_engine);
 
     CLOG_INFO(LOG_EN, 2, "Engine %016llx %s", engine, engine_type);
-    return PyLong_FromVoidPtr(preview_engine);
+    return PyLong_FromVoidPtr(preview_engine.get());
   }
   else {
     if (bl_engine->type->flag & RE_USE_GPU_CONTEXT) {
@@ -164,7 +151,12 @@ static PyObject *engine_free_func(PyObject * /*self*/, PyObject *args)
   Engine *engine = (Engine *)PyLong_AsVoidPtr(pyengine);
 
   if (preview_engine) {
-    BLI_timer_register(1, delete_preview_engine, nullptr, nullptr, preview_engine_lifetime, true);
+    BLI_timer_register(1,
+                       preview_engine->delete_preview_engine,
+                       &preview_engine,
+                       nullptr,
+                       preview_engine->preview_engine_lifetime,
+                       true);
     CLOG_INFO(LOG_EN, 2, "Engine %016llx", engine);
     Py_RETURN_NONE;
   }

source/blender/render/hydra/scene_delegate/blender_scene_delegate.cc

@@ -477,10 +477,18 @@ pxr::VtValue BlenderSceneDelegate::GetLightParamValue(pxr::SdfPath const &id,
   return pxr::VtValue();
 }
 
-void BlenderSceneDelegate::clear_data()
+void BlenderSceneDelegate::clear()
 {
-  objects.clear();
+  for (auto it = materials.begin(); it != materials.end(); ++it) {
+    it->second->remove_prim();
+  }
+
+  for (auto it = objects.begin(); it != objects.end(); ++it) {
+    it->second->remove_prim();
+  }
+
   materials.clear();
+  objects.clear();
 }
 
 }  // namespace blender::render::hydra

source/blender/render/hydra/scene_delegate/blender_scene_delegate.h

@@ -29,7 +29,7 @@ class BlenderSceneDelegate : public pxr::HdSceneDelegate {
   ~BlenderSceneDelegate() override = default;
 
   void populate(Depsgraph *depsgraph, bContext *context);
-  void clear_data();
+  void clear();
 
   // delegate methods
   pxr::HdMeshTopology GetMeshTopology(pxr::SdfPath const &id) override;

source/blender/render/hydra/scene_delegate/material.cc

@@ -120,7 +120,7 @@ void MaterialData::remove_prim()
 {
   pxr::SdfPath p_id = prim_id(scene_delegate, (Material *)id);
   scene_delegate->GetRenderIndex().RemoveSprim(pxr::HdPrimTypeTokens->material, p_id);
-  CLOG_INFO(LOG_BSD, 2, "Remove: %s", name().c_str());
+  //CLOG_INFO(LOG_BSD, 2, "Remove: %s", name().c_str());
 }
 
 void MaterialData::mark_prim_dirty(DirtyBits dirty_bits)

source/blender/render/hydra/scene_delegate/mesh.cc

@@ -219,7 +219,7 @@ void MeshData::remove_prim()
   }
 
   scene_delegate->GetRenderIndex().RemoveRprim(p_id);
-  CLOG_INFO(LOG_BSD, 2, "Remove: %s", name().c_str());
+  //CLOG_INFO(LOG_BSD, 2, "Remove: %s", name().c_str());
 }
 
 void MeshData::mark_prim_dirty(DirtyBits dirty_bits)

source/blender/render/hydra/viewport_engine.cc

@@ -244,6 +244,12 @@ void ViewportEngine::sync(Depsgraph *depsgraph,
                           bContext *context,
                           pxr::HdRenderSettingsMap &render_settings)
 {
+  if (!scene_delegate) {
+    scene_delegate = std::make_unique<BlenderSceneDelegate>(
+        render_index.get(),
+        pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
+        BlenderSceneDelegate::EngineType::VIEWPORT);
+  }
   scene_delegate->populate(depsgraph, context);
 
   for (auto const &setting : render_settings) {