scripts/modules/bpy_hydra.py

@@ -19,7 +19,7 @@ class CustomHydraRenderEngine(HydraRenderEngine):
     def register(cls):
         super().register()
 
-        bpy_hydra.register_plugins(["/path/to/plugin")], ["/additional/system/path")])
+        bpy_hydra.register_plugins(["/path/to/plugin")])
 
     def get_delegate_settings(self, engine_type):
         return {
@@ -59,6 +59,7 @@ class HydraRenderEngine(bpy.types.RenderEngine):
             return
 
         _bpy_hydra.engine_free(self.engine_ptr)
+        del self.engine_ptr
 
     @classmethod
     def register(cls):
@@ -75,16 +76,14 @@ class HydraRenderEngine(bpy.types.RenderEngine):
 
     # final render
     def update(self, data, depsgraph):
-        pass
-
-    def render(self, depsgraph):
         engine_type = 'PREVIEW' if self.is_preview else 'FINAL'
-
         self.engine_ptr = _bpy_hydra.engine_create(self.as_pointer(), engine_type, self.delegate_id)
         delegate_settings = self.get_delegate_settings(engine_type)
-
         _bpy_hydra.engine_sync(self.engine_ptr, depsgraph.as_pointer(), bpy.context.as_pointer(), delegate_settings)
-        _bpy_hydra.engine_render(self.engine_ptr, depsgraph.as_pointer())
+
+    def render(self, depsgraph):
+        if self.engine_ptr:
+            _bpy_hydra.engine_render(self.engine_ptr, depsgraph.as_pointer())
 
     # viewport render
     def view_update(self, context, depsgraph):

source/blender/render/hydra/preview_engine.cc

@@ -5,17 +5,64 @@
 
 #include "camera.h"
 #include "preview_engine.h"
+#include "BLI_timer.h"
 
 namespace blender::render::hydra {
 
+const double LIFETIME = 180.0;
+
+std::unique_ptr<PreviewEngine> PreviewEngine::instance;
+
+void PreviewEngine::schedule_free()
+{
+  instance->render_delegate->Stop();
+
+  /* Register timer for schedule free PreviewEngine instance */
+  BLI_timer_register((uintptr_t)instance.get(),
+                      free_instance,
+                      nullptr,
+                      nullptr,
+                      LIFETIME,
+                      true);
+}
+
+PreviewEngine *PreviewEngine::get_instance(RenderEngine *bl_engine, const std::string &render_delegate_id)
+{
+  if (!instance) {
+    instance = std::make_unique<PreviewEngine>(bl_engine, render_delegate_id);
+  }
+  if (BLI_timer_is_registered((uintptr_t)instance.get())) {
+    /* Unregister timer while PreviewEngine is working */
+    BLI_timer_unregister((uintptr_t)instance.get());
+  }
+  instance->update(bl_engine, render_delegate_id);
+
+  return instance.get();
+}
+
+double PreviewEngine::free_instance(uintptr_t uuid, void *user_data)
+{
+  if (!instance->render_task_delegate->is_converged()) {
+    /* Restart timer if render isn't completed */
+    return LIFETIME;
+  }
+
+  CLOG_INFO(LOG_EN, 2, "");
+  instance = nullptr;
+  return -1;
+}
+
 void PreviewEngine::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::PREVIEW);
+  if (!scene_delegate) {
+    scene_delegate = std::make_unique<BlenderSceneDelegate>(
+        render_index.get(),
+        pxr::SdfPath::AbsoluteRootPath().AppendElementString("scene"),
+        BlenderSceneDelegate::EngineType::PREVIEW);
+  }
+  scene_delegate->clear();
   scene_delegate->populate(depsgraph, context);
 
   for (auto const &setting : render_settings) {
@@ -70,6 +117,12 @@ void PreviewEngine::render(Depsgraph *depsgraph)
   update_render_result(layer_name, res[0], res[1], pixels);
 }
 
+void PreviewEngine::update(RenderEngine *bl_engine, const std::string &render_delegate_id)
+{
+  this->bl_engine = bl_engine;
+  /* TODO: recreate render_delegate when render_delegate_id is changed */
+}
+
 void PreviewEngine::update_render_result(const std::string &layer_name,
                                          int width,
                                          int height,

source/blender/render/hydra/preview_engine.h

@@ -8,21 +8,28 @@
 namespace blender::render::hydra {
 
 class PreviewEngine : public FinalEngine {
+ private:
+  /* Singleton class instance */
+  static std::unique_ptr<PreviewEngine> instance;
+  static double free_instance(uintptr_t uuid, void *user_data);
+
  public:
+  static PreviewEngine *get_instance(RenderEngine *bl_engine, const std::string &render_delegate_id);
+  static void schedule_free();
+
   using FinalEngine::FinalEngine;
   void sync(Depsgraph *depsgraph,
             bContext *context,
             pxr::HdRenderSettingsMap &render_settings) override;
   void render(Depsgraph *depsgraph) override;
 
- protected:
+ private:
+  void update(RenderEngine *bl_engine, const std::string &render_delegate_id);
   void update_render_result(const std::string &layer_name,
                             int width,
                             int height,
                             std::vector<float> &pixels);
 
- protected:
-  pxr::HdRenderSettingsMap render_settings;
 };
 
 }  // namespace blender::render::hydra

source/blender/render/hydra/python.cc

@@ -16,6 +16,8 @@
 #include "utils.h"
 #include "viewport_engine.h"
 
+#include "BLI_timer.h"
+
 namespace blender::render::hydra {
 
 static PyObject *init_func(PyObject * /*self*/, PyObject *args)
@@ -112,7 +114,7 @@ static PyObject *engine_create_func(PyObject * /*self*/, PyObject *args)
     engine = new ViewportEngine(bl_engine, render_delegate_id);
   }
   else if (STREQ(engine_type, "PREVIEW")) {
-    engine = new PreviewEngine(bl_engine, render_delegate_id);
+    engine = PreviewEngine::get_instance(bl_engine, render_delegate_id);
   }
   else {
     if (bl_engine->type->flag & RE_USE_GPU_CONTEXT) {
@@ -136,7 +138,13 @@ static PyObject *engine_free_func(PyObject * /*self*/, PyObject *args)
   }
 
   Engine *engine = (Engine *)PyLong_AsVoidPtr(pyengine);
-  delete engine;
+  PreviewEngine *preview_engine = dynamic_cast<PreviewEngine *>(engine);
+  if (preview_engine) {
+    PreviewEngine::schedule_free();
+  }
+  else {
+    delete engine;
+  }
 
   CLOG_INFO(LOG_EN, 2, "Engine %016llx", engine);
   Py_RETURN_NONE;

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

@@ -434,4 +434,18 @@ pxr::VtValue BlenderSceneDelegate::GetLightParamValue(pxr::SdfPath const &id,
   return pxr::VtValue();
 }
 
+void BlenderSceneDelegate::clear()
+{
+  for (auto &it : materials) {
+    it.second->remove();
+  }
+
+  for (auto &it : objects) {
+    it.second->remove();
+  }
+
+  materials.clear();
+  objects.clear();
+}
+
 }  // namespace blender::render::hydra

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

@@ -33,6 +33,7 @@ class BlenderSceneDelegate : public pxr::HdSceneDelegate {
   ~BlenderSceneDelegate() override = default;
 
   void populate(Depsgraph *depsgraph, bContext *context);
+  void clear();
 
   // delegate methods
   pxr::HdMeshTopology GetMeshTopology(pxr::SdfPath const &id) override;

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

@@ -7,7 +7,6 @@
 #include <pxr/imaging/hd/tokens.h>
 #include <pxr/usd/usdLux/tokens.h>
 
-#include "BKE_light.h"
 #include "DNA_light_types.h"
 
 #include "blender_scene_delegate.h"
@@ -80,13 +79,14 @@ void LightData::init()
       break;
   }
 
+  p_type = prim_type(light);
+
   /* TODO: temporary value, it should be delivered through Python UI */
   data[pxr::HdLightTokens->exposure] = 1.0f;
 }
 
-pxr::TfToken LightData::prim_type()
+pxr::TfToken LightData::prim_type(Light *light)
 {
-  Light *light = (Light *)((Object *)id)->data;
   pxr::TfToken ret;
   switch (light->type) {
     case LA_LOCAL:
@@ -155,21 +155,27 @@ bool LightData::update_visibility(View3D *view3d)
 void LightData::insert()
 {
   CLOG_INFO(LOG_BSD, 2, "%s", id->name);
-  scene_delegate->GetRenderIndex().InsertSprim(prim_type(), scene_delegate, p_id);
+  scene_delegate->GetRenderIndex().InsertSprim(p_type, scene_delegate, p_id);
 }
 
 void LightData::remove()
 {
   CLOG_INFO(LOG_BSD, 2, "%s", id->name);
-  scene_delegate->GetRenderIndex().RemoveSprim(prim_type(), p_id);
+  scene_delegate->GetRenderIndex().RemoveSprim(p_type, p_id);
 }
 
 void LightData::update()
 {
-  /* TODO: prim_type was changed we have to do remove..add light */
-
   CLOG_INFO(LOG_BSD, 2, "%s", id->name);
 
+  Light *light = (Light *)((Object *)id)->data;
+  if (prim_type(light) != p_type) {
+    remove();
+    init();
+    insert();
+    return;
+  }
+
   pxr::HdDirtyBits bits = pxr::HdLight::Clean;
   if (id->recalc & ID_RECALC_GEOMETRY) {
     init();

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

@@ -7,6 +7,8 @@
 #include <pxr/usd/sdf/assetPath.h>
 #include <pxr/usd/sdf/path.h>
 
+#include "BKE_light.h"
+
 #include "object.h"
 
 namespace blender::render::hydra {
@@ -24,7 +26,8 @@ class LightData : public ObjectData {
 
  private:
   std::map<pxr::TfToken, pxr::VtValue> data;
-  pxr::TfToken prim_type();
+  pxr::TfToken p_type;
+  pxr::TfToken prim_type(Light *light);
 };
 
 }  // namespace blender::render::hydra