source/blender/render/hydra/engine.cc

@@ -56,6 +56,11 @@ Engine::Engine(RenderEngine *bl_engine, const std::string &render_delegate_name)
   engine_ = std::make_unique<pxr::HdEngine>();
 }
 
+void Engine::sync(Depsgraph *depsgraph, bContext *context)
+{
+  scene_delegate_->populate(depsgraph, context);
+}
+
 void Engine::set_sync_setting(const std::string &key, const pxr::VtValue &val)
 {
   scene_delegate_->set_setting(key, val);

source/blender/render/hydra/engine.h

@@ -28,7 +28,7 @@ class Engine {
   Engine(RenderEngine *bl_engine, const std::string &render_delegate_name);
   virtual ~Engine() = default;
 
-  virtual void sync(Depsgraph *depsgraph, bContext *context) = 0;
+  void sync(Depsgraph *depsgraph, bContext *context);
   virtual void render(Depsgraph *depsgraph) = 0;
 
   void set_sync_setting(const std::string &key, const pxr::VtValue &val);

source/blender/render/hydra/final_engine.cc

@@ -13,11 +13,6 @@
 
 namespace blender::render::hydra {
 
-void FinalEngine::sync(Depsgraph *depsgraph, bContext *context)
-{
-  scene_delegate_->populate(depsgraph, context);
-}
-
 void FinalEngine::render(Depsgraph *depsgraph)
 {
   prepare_for_render(depsgraph);

source/blender/render/hydra/final_engine.h

@@ -11,8 +11,7 @@ class FinalEngine : public Engine {
  public:
   using Engine::Engine;
 
-  virtual void sync(Depsgraph *depsgraph, bContext *context) override;
-  virtual void render(Depsgraph *b_depsgraph) override;
+  void render(Depsgraph *b_depsgraph) override;
 
  protected:
   void update_render_result();

source/blender/render/hydra/preview_engine.cc

@@ -13,33 +13,35 @@ const double LIFETIME = 180.0;
 
 std::unique_ptr<PreviewEngine> PreviewEngine::instance_;
 
-PreviewEngine *PreviewEngine::get_instance(RenderEngine *bl_engine,
-                                           const std::string &render_delegate_name)
+PreviewEngine *PreviewEngine::create(RenderEngine *bl_engine,
+                                     const std::string &render_delegate_name)
 {
   if (!instance_) {
     instance_ = std::make_unique<PreviewEngine>(bl_engine, render_delegate_name);
   }
-  if (BLI_timer_is_registered((uintptr_t)instance_.get())) {
-    /* Unregister timer while PreviewEngine is working */
-    BLI_timer_unregister((uintptr_t)instance_.get());
+  else if (instance_->render_delegate_name != render_delegate_name) {
+    instance_->render_delegate_->Stop();
+    instance_ = std::make_unique<PreviewEngine>(bl_engine, render_delegate_name);
+  }
+  else {
+    instance_->bl_engine_ = bl_engine;
+  }
+
+  if (BLI_timer_is_registered((uintptr_t)&instance_)) {
+    /* Unregister timer while PreviewEngine is working */
+    BLI_timer_unregister((uintptr_t)&instance_);
   }
-  instance_->update(bl_engine, render_delegate_name);
 
   return instance_.get();
 }
 
-void PreviewEngine::schedule_free()
+void PreviewEngine::free()
 {
   instance_->render_delegate_->Stop();
+  instance_->scene_delegate_->clear();
 
   /* Register timer for schedule free PreviewEngine instance */
-  BLI_timer_register((uintptr_t)instance_.get(), free_instance, nullptr, nullptr, LIFETIME, true);
-}
-
-void PreviewEngine::sync(Depsgraph *depsgraph, bContext *context)
-{
-  scene_delegate_->clear();
-  scene_delegate_->populate(depsgraph, context);
+  BLI_timer_register((uintptr_t)&instance_, free_instance, nullptr, nullptr, LIFETIME, true);
 }
 
 void PreviewEngine::render(Depsgraph *depsgraph)
@@ -83,15 +85,6 @@ double PreviewEngine::free_instance(uintptr_t uuid, void *user_data)
   return -1;
 }
 
-void PreviewEngine::update(RenderEngine *bl_engine, const std::string &render_delegate_name)
-{
-  bl_engine_ = bl_engine;
-  if (render_delegate_name != render_delegate_name) {
-    render_delegate_->Stop();
-    instance_.reset(new PreviewEngine(bl_engine, render_delegate_name));
-  }
-}
-
 void PreviewEngine::update_render_result(std::vector<float> &pixels)
 {
   RenderResult *result = RE_engine_begin_result(

source/blender/render/hydra/preview_engine.h

@@ -9,18 +9,15 @@ namespace blender::render::hydra {
 
 class PreviewEngine : public FinalEngine {
  public:
-  using FinalEngine::FinalEngine;
-  static PreviewEngine *get_instance(RenderEngine *bl_engine,
-                                     const std::string &render_delegate_name);
-  static void schedule_free();
+  static PreviewEngine *create(RenderEngine *bl_engine, const std::string &render_delegate_name);
+  static void free();
 
-  void sync(Depsgraph *depsgraph, bContext *context) override;
   void render(Depsgraph *depsgraph) override;
 
  private:
+  using FinalEngine::FinalEngine;
   static double free_instance(uintptr_t uuid, void *user_data);
 
-  void update(RenderEngine *bl_engine, const std::string &render_delegate_name);
   void update_render_result(std::vector<float> &pixels);
 
   /* Singleton class instance */

source/blender/render/hydra/python.cc

@@ -111,7 +111,7 @@ static PyObject *engine_create_func(PyObject * /*self*/, PyObject *args)
     engine = new ViewportEngine(bl_engine, render_delegate_id);
   }
   else if (STREQ(engine_type, "PREVIEW")) {
-    engine = PreviewEngine::get_instance(bl_engine, render_delegate_id);
+    engine = PreviewEngine::create(bl_engine, render_delegate_id);
   }
   else {
     if (bl_engine->type->flag & RE_USE_GPU_CONTEXT) {
@@ -136,7 +136,7 @@ static PyObject *engine_free_func(PyObject * /*self*/, PyObject *args)
   Engine *engine = (Engine *)PyLong_AsVoidPtr(pyengine);
   PreviewEngine *preview_engine = dynamic_cast<PreviewEngine *>(engine);
   if (preview_engine) {
-    PreviewEngine::schedule_free();
+    PreviewEngine::free();
   }
   else {
     delete engine;

source/blender/render/hydra/viewport_engine.cc

@@ -217,11 +217,6 @@ void DrawTexture::free()
   texture_ = nullptr;
 }
 
-void ViewportEngine::sync(Depsgraph *depsgraph, bContext *context)
-{
-  scene_delegate_->populate(depsgraph, context);
-}
-
 void ViewportEngine::render(Depsgraph *depsgraph)
 {
   /* Empty function */

source/blender/render/hydra/viewport_engine.h

@@ -34,7 +34,6 @@ class ViewportEngine : public Engine {
  public:
   using Engine::Engine;
 
-  void sync(Depsgraph *depsgraph, bContext *context) override;
   void render(Depsgraph *depsgraph) override;
   void render(Depsgraph *depsgraph, bContext *context);