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

@@ -217,13 +217,11 @@ void BlenderSceneDelegate::clear()
   for (auto &it : instancers_) {
     it.second->remove();
   }
-  for (auto &it : materials_) {
-    it.second->remove();
-  }
+
 
   objects_.clear();
   instancers_.clear();
-  materials_.clear();
+  materials_.clear_and_shrink();
 
   depsgraph = nullptr;
   context = nullptr;
@@ -297,11 +295,11 @@ LightData *BlenderSceneDelegate::light_data(pxr::SdfPath const &id) const
 
 MaterialData *BlenderSceneDelegate::material_data(pxr::SdfPath const &id) const
 {
-  auto it = materials_.find(id);
-  if (it == materials_.end()) {
+  const std::unique_ptr<MaterialData> *value = materials_.lookup_ptr(id);
+  if (value == nullptr) {
     return nullptr;
   }
-  return it->second.get();
+  return value->get();
 }
 
 InstancerData *BlenderSceneDelegate::instancer_data(pxr::SdfPath const &id, bool child_id) const
@@ -585,14 +583,14 @@ void BlenderSceneDelegate::remove_unused_objects()
   for (auto &it : instancers_) {
     it.second->available_materials(available_materials);
   }
-  for (auto it = materials_.begin(); it != materials_.end(); ++it) {
-    if (available_materials.find(it->first) != available_materials.end()) {
-      continue;
-    }
-    it->second->remove();
-    materials_.erase(it);
-    it = materials_.begin();
+
+  materials_.remove_if([&](auto item) {
+    bool ret = available_materials.find(item.key) == available_materials.end();
+  if (ret){
+    item.value->remove();
   }
+  return ret;
+  });
 }
 
 void BlenderSceneDelegate::update_visibility()

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

@@ -8,6 +8,7 @@
 
 #include "BKE_context.h"
 #include "DEG_depsgraph.h"
+#include "BLI_hash.hh"
 
 #include "CLG_log.h"
 
@@ -18,6 +19,13 @@
 #include "object.h"
 #include "world.h"
 
+template<> struct blender::DefaultHash<pxr::SdfPath> {
+  uint64_t operator()(const pxr::SdfPath &value) const
+  {
+    return pxr::SdfPath::Hash()(value);
+  }
+};
+
 namespace blender::render::hydra {
 
 extern struct CLG_LogRef *LOG_RENDER_HYDRA_SCENE;

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

@@ -8,6 +8,7 @@
 #include <pxr/usd/sdf/path.h>
 
 #include "DNA_material_types.h"
+#include "BLI_map.hh"
 
 #include "id.h"
 
@@ -37,7 +38,6 @@ class MaterialData : public IdData {
   pxr::VtValue material_network_map_;
 };
 
-using MaterialDataMap =
-    pxr::TfHashMap<pxr::SdfPath, std::unique_ptr<MaterialData>, pxr::SdfPath::Hash>;
+using MaterialDataMap = Map<pxr::SdfPath, std::unique_ptr<MaterialData>>;
 
 }  // namespace blender::render::hydra

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

@@ -304,8 +304,8 @@ void MeshData::write_materials()
     pxr::SdfPath p_id = scene_delegate_->material_prim_id(mat);
     m.mat_data = scene_delegate_->material_data(p_id);
     if (!m.mat_data) {
-      scene_delegate_->materials_[p_id] = std::make_unique<MaterialData>(
-          scene_delegate_, mat, p_id);
+      scene_delegate_->materials_.add_overwrite(p_id,
+          std::make_unique<MaterialData>(scene_delegate_, mat, p_id));
       m.mat_data = scene_delegate_->material_data(p_id);
       m.mat_data->init();
       m.mat_data->insert();