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

@@ -307,6 +307,15 @@ void BlenderSceneDelegate::update_instancers(Object *object)
   i_data->update_visibility();
 }
 
+void BlenderSceneDelegate::update_instancer_as_parent(Object *object)
+{
+  pxr::SdfPath id = instancer_prim_id(object);
+  InstancerData *i_data = instancer_data(id);
+  if (i_data) {
+    i_data->update_as_parent();
+  }
+}
+
 void BlenderSceneDelegate::update_world()
 {
   World *world = scene->world;

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

@@ -74,6 +74,7 @@ class BlenderSceneDelegate : public pxr::HdSceneDelegate {
 
   void update_objects(Object *object);
   void update_instancers(Object *object);
+  void update_instancer_as_parent(Object *object);
   void update_world();
   void check_updates();
   void add_new_objects();

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

@@ -51,9 +51,6 @@ void InstancerData::insert()
 {
   ID_LOG(2, "");
   scene_delegate_->GetRenderIndex().InsertInstancer(scene_delegate_, prim_id);
-  for (auto &it : instances_) {
-    it.second.obj_data->insert();
-  }
 }
 
 void InstancerData::remove()
@@ -149,6 +146,7 @@ void InstancerData::check_update(Object *object)
   }
   ObjectData *obj_data = it->second.obj_data.get();
   obj_data->update();
+  obj_data->transform = pxr::GfMatrix4d(1.0);
 
   pxr::HdDirtyBits bits = pxr::HdChangeTracker::Clean;
   if (object->id.recalc & ID_RECALC_TRANSFORM) {
@@ -189,6 +187,13 @@ void InstancerData::available_materials(std::set<pxr::SdfPath> &paths) const
   }
 }
 
+void InstancerData::update_as_parent()
+{
+  set_instances();
+  scene_delegate_->GetRenderIndex().GetChangeTracker().MarkInstancerDirty(
+      prim_id, pxr::HdChangeTracker::AllDirty);
+}
+
 pxr::SdfPath InstancerData::object_prim_id(Object *object) const
 {
   /* Making id of object in form like <prefix>_<pointer in 16 hex digits format> */

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

@@ -38,6 +38,7 @@ class InstancerData : public ObjectData {
   void check_update(Object *object);
   void check_remove(std::set<std::string> &available_objects);
   void available_materials(std::set<pxr::SdfPath> &paths) const;
+  void update_as_parent();
 
  private:
   pxr::SdfPath object_prim_id(Object *object) const;

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

@@ -65,8 +65,16 @@ void MeshData::remove()
 
 void MeshData::update()
 {
-  pxr::HdDirtyBits bits = pxr::HdChangeTracker::Clean;
   Object *object = (Object *)id;
+  if ((id->recalc & ID_RECALC_TRANSFORM) && parent_ != object->parent) {
+    /* parent was changed */
+    parent_ = object->parent;
+    if (parent_) {
+      scene_delegate_->update_instancer_as_parent(parent_);
+    }
+  }
+
+  pxr::HdDirtyBits bits = pxr::HdChangeTracker::Clean;
   if ((id->recalc & ID_RECALC_GEOMETRY) || (((ID *)object->data)->recalc & ID_RECALC_GEOMETRY)) {
     init();
     bits = pxr::HdChangeTracker::AllDirty;

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

@@ -13,7 +13,10 @@ namespace blender::render::hydra {
 ObjectData::ObjectData(BlenderSceneDelegate *scene_delegate,
                        Object *object,
                        pxr::SdfPath const &prim_id)
-    : IdData(scene_delegate, (ID *)object, prim_id), transform(pxr::GfMatrix4d(1.0)), visible(true)
+    : IdData(scene_delegate, (ID *)object, prim_id),
+      transform(pxr::GfMatrix4d(1.0)),
+      visible(true),
+      parent_(object->parent)
 {
 }
 

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

@@ -29,7 +29,9 @@ class ObjectData : public IdData {
   bool visible;
 
  protected:
-  void write_transform();
+  virtual void write_transform();
+
+  Object *parent_;
 };
 
 using ObjectDataMap =