doc/python_api/examples/bpy.types.HydraRenderEngine.py

@@ -32,6 +32,12 @@ class CustomHydraRenderEngine(bpy.types.HydraRenderEngine):
             'aovToken:Depth': "depth",
         }
 
+    # Settings used by the synchronization process.
+    def get_sync_settings(self, engine_type):
+        return {
+            'lightToken:object:visibility:camera': False,
+        }
+
     # RenderEngine methods for update, render and draw are implemented in
     # HydraRenderEngine. Optionally extra work can be done before or after
     # by implementing the methods like this.

scripts/modules/bpy_types.py

@@ -1269,6 +1269,13 @@ class HydraRenderEngine(RenderEngine):
                 import _bpy_hydra
                 _bpy_hydra.engine_free(self.engine_ptr)
 
+    def get_sync_settings(self, engine_type: str):
+        """
+        Provide specific settings for Hydra scene delegate. Available settings:
+            "lightToken:<token name>": <token value>
+        """
+        return {}
+
     def get_render_settings(self, engine_type: str):
         """
         Provide render settings for `HdRenderDelegate`.
@@ -1285,6 +1292,9 @@ class HydraRenderEngine(RenderEngine):
         if not self.engine_ptr:
             return
 
+        for key, val in self.get_sync_settings(engine_type).items():
+            _bpy_hydra.engine_set_sync_setting(self.engine_ptr, key, val)
+
         _bpy_hydra.engine_update(self.engine_ptr, depsgraph, None)
 
         for key, val in self.get_render_settings('PREVIEW' if self.is_preview else 'FINAL').items():
@@ -1305,6 +1315,9 @@ class HydraRenderEngine(RenderEngine):
         if not self.engine_ptr:
             return
 
+        for key, val in self.get_sync_settings('VIEWPORT').items():
+            _bpy_hydra.engine_set_sync_setting(self.engine_ptr, key, val)
+
         _bpy_hydra.engine_update(self.engine_ptr, depsgraph, context)
 
         for key, val in self.get_render_settings('VIEWPORT').items():

source/blender/io/usd/hydra/hydra_scene_delegate.cc

@@ -234,6 +234,16 @@ void HydraSceneDelegate::clear()
   view3d = nullptr;
 }
 
+void HydraSceneDelegate::set_sync_setting(const std::string &key, const pxr::VtValue &val)
+{
+  if (STRPREFIX(key.c_str(), "lightToken:")) {
+    sync_settings.light_tokens.add_overwrite(pxr::TfToken(key.substr(key.find(":") + 1)), val);
+  }
+  else {
+    CLOG_WARN(LOG_HYDRA_SCENE, "Unsupported sync setting: %s", key.c_str());
+  }
+}
+
 pxr::SdfPath HydraSceneDelegate::prim_id(ID *id, const char *prefix) const
 {
   /* Making id of object in form like <prefix>_<pointer in 16 hex digits format> */

source/blender/io/usd/hydra/hydra_scene_delegate.h

@@ -37,6 +37,11 @@ class HydraSceneDelegate : public pxr::HdSceneDelegate {
   friend MaterialData; /* has access to objects and instancers */
 
  public:
+  struct SyncSettings {
+    /* Is used by render addons to provide specific settings for objects.
+     * Currently it is used for lights only */
+    Map<pxr::TfToken, pxr::VtValue> light_tokens;
+  };
   struct ShadingSettings {
     bool use_scene_lights = true;
     bool use_scene_world = true;
@@ -51,6 +56,7 @@ class HydraSceneDelegate : public pxr::HdSceneDelegate {
   View3D *view3d = nullptr;
   Main *bmain = nullptr;
   Scene *scene = nullptr;
+  SyncSettings sync_settings;
   ShadingSettings shading_settings;
 
  private:
@@ -86,6 +92,7 @@ class HydraSceneDelegate : public pxr::HdSceneDelegate {
 
   void populate(Depsgraph *depsgraph, View3D *v3d);
   void clear();
+  void set_sync_setting(const std::string &key, const pxr::VtValue &val);
 
  private:
   pxr::SdfPath prim_id(ID *id, const char *prefix) const;

source/blender/io/usd/hydra/light.cc

@@ -140,6 +140,11 @@ pxr::VtValue LightData::get_data(pxr::TfToken const &key) const
     return pxr::VtValue(it->second);
   }
 
+  const pxr::VtValue *ret_ptr = scene_delegate_->sync_settings.light_tokens.lookup_ptr(key);
+  if (ret_ptr) {
+    return *ret_ptr;
+  }
+
   return pxr::VtValue();
 }
 

source/blender/render/hydra/engine.cc

@@ -108,6 +108,13 @@ void Engine::sync(Depsgraph *depsgraph, bContext *context)
   }
 }
 
+void Engine::set_sync_setting(const std::string &key, const pxr::VtValue &val)
+{
+  if (hydra_scene_delegate_) {
+    hydra_scene_delegate_->set_sync_setting(key, val);
+  }
+}
+
 void Engine::set_render_setting(const std::string &key, const pxr::VtValue &val)
 {
   render_delegate_->SetRenderSetting(pxr::TfToken(key), val);

source/blender/render/hydra/engine.h

@@ -58,6 +58,7 @@ class Engine {
   void sync(Depsgraph *depsgraph, bContext *context);
   virtual void render() = 0;
 
+  void set_sync_setting(const std::string &key, const pxr::VtValue &val);
   virtual void set_render_setting(const std::string &key, const pxr::VtValue &val);
 
  protected:

source/blender/render/hydra/python.cc

@@ -146,6 +146,22 @@ static pxr::VtValue get_setting_val(PyObject *pyval)
   return val;
 }
 
+static PyObject *engine_set_sync_setting_func(PyObject * /*self*/, PyObject *args)
+{
+  PyObject *pyengine, *pyval;
+  char *key;
+  if (!PyArg_ParseTuple(args, "OsO", &pyengine, &key, &pyval)) {
+    Py_RETURN_NONE;
+  }
+
+  Engine *engine = static_cast<Engine *>(PyLong_AsVoidPtr(pyengine));
+
+  CLOG_INFO(LOG_HYDRA_RENDER, 3, "Engine %p: %s", engine, key);
+  engine->set_sync_setting(key, get_setting_val(pyval));
+
+  Py_RETURN_NONE;
+}
+
 static PyObject *engine_set_render_setting_func(PyObject * /*self*/, PyObject *args)
 {
   PyObject *pyengine, *pyval;
@@ -183,6 +199,7 @@ static PyMethodDef methods[] = {
     {"engine_update", engine_update_func, METH_VARARGS, ""},
     {"engine_render", engine_render_func, METH_VARARGS, ""},
     {"engine_view_draw", engine_view_draw_func, METH_VARARGS, ""},
+    {"engine_set_sync_setting", engine_set_sync_setting_func, METH_VARARGS, ""},
     {"engine_set_render_setting", engine_set_render_setting_func, METH_VARARGS, ""},
 
     {"cache_or_get_image_file", cache_or_get_image_file_func, METH_VARARGS, ""},