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

@@ -22,21 +22,6 @@ BlenderSceneDelegate::BlenderSceneDelegate(pxr::HdRenderIndex *parent_index,
 {
 }
 
-void BlenderSceneDelegate::set_material(MeshData &mesh_data)
-{
-  Material *material = mesh_data.material();
-  if (!material) {
-    mesh_data.material_id = pxr::SdfPath::EmptyPath();
-    return;
-  }
-  pxr::SdfPath id = MaterialData::prim_id(this, material);
-  MaterialData *mat_data = material_data(id);
-  if (!mat_data) {
-    materials[id] = MaterialData::create(this, material);
-  }
-  mesh_data.material_id = id;
-}
-
 void BlenderSceneDelegate::update_material(Material *material)
 {
   MaterialData *mat_data = material_data(MaterialData::prim_id(this, material));
@@ -189,8 +174,12 @@ void BlenderSceneDelegate::update_collection(bool remove, bool visibility)
     std::set<pxr::SdfPath> available_materials;
     for (auto &obj : objects) {
       MeshData *m_data = dynamic_cast<MeshData *>(obj.second.get());
-      if (m_data && !m_data->material_id.IsEmpty()) {
+      if (!m_data) {
-        available_materials.insert(m_data->material_id);
+        continue;
+      }
+      pxr::SdfPath mat_id = m_data->material_id();
+      if (!mat_id.IsEmpty()) {
+        available_materials.insert(mat_id);
       }
     }
     for (auto it = materials.begin(); it != materials.end(); ++it) {
@@ -393,7 +382,7 @@ pxr::HdPrimvarDescriptorVector BlenderSceneDelegate::GetPrimvarDescriptors(
 
 pxr::SdfPath BlenderSceneDelegate::GetMaterialId(pxr::SdfPath const &rprim_id)
 {
-  return mesh_data(rprim_id)->material_id;
+  return mesh_data(rprim_id)->material_id();
 }
 
 pxr::VtValue BlenderSceneDelegate::GetMaterialResource(pxr::SdfPath const &id)

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

@@ -63,7 +63,6 @@ class BlenderSceneDelegate : public pxr::HdSceneDelegate {
 
   void add_update_object(Object *object, bool geometry, bool transform, bool shading);
   void add_update_instance(DupliObject *dupli);
-  void set_material(MeshData &mesh_data);
   void update_material(Material *material);
   void update_world();
   void update_collection(bool remove, bool visibility);

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

@@ -13,13 +13,6 @@ IdData::IdData(BlenderSceneDelegate *scene_delegate, ID *id)
 {
 }
 
-std::string IdData::name() const
-{
-  char str[MAX_ID_FULL_NAME];
-  BKE_id_full_name_get(str, id, 0);
-  return str;
-}
-
 pxr::VtValue IdData::get_data(pxr::TfToken const &key) const
 {
   return pxr::VtValue();

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

@@ -26,8 +26,6 @@ class IdData {
   virtual pxr::VtValue get_data(pxr::TfToken const &key) const;
   template<class T> const T get_data(pxr::TfToken const &key) const;
 
-  std::string name() const;
-
  protected:
   BlenderSceneDelegate *scene_delegate;
   ID *id;

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

@@ -107,7 +107,7 @@ void MaterialData::export_mtlx()
     Py_DECREF(result);
   }
   else {
-    CLOG_ERROR(LOG_BSD, "Export error for %s", name().c_str());
+    CLOG_ERROR(LOG_BSD, "Export error for %s", id->name);
     PyErr_Print();
   }
   Py_DECREF(module);
@@ -115,7 +115,7 @@ void MaterialData::export_mtlx()
   PyGILState_Release(gstate);
 
   mtlx_path = pxr::SdfAssetPath(path, path);
-  CLOG_INFO(LOG_BSD, 2, "Export: %s, mtlx=%s", name().c_str(), mtlx_path.GetResolvedPath().c_str());
+  CLOG_INFO(LOG_BSD, 2, "Export: %s, mtlx=%s", id->name, mtlx_path.GetResolvedPath().c_str());
 }
 
 void MaterialData::insert()

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

@@ -13,7 +13,11 @@
 
 namespace blender::render::hydra {
 
+class MeshData;
+
 class MaterialData : IdData {
+  friend MeshData;
+
  public:
   static std::unique_ptr<MaterialData> create(BlenderSceneDelegate *scene_delegate,
                                             Material *material);

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

@@ -16,7 +16,7 @@
 namespace blender::render::hydra {
 
 MeshData::MeshData(BlenderSceneDelegate *scene_delegate, Object *object)
-    : ObjectData(scene_delegate, object)
+    : ObjectData(scene_delegate, object), mat_data(nullptr)
 {
   CLOG_INFO(LOG_BSD, 2, "%s, id=%s", id->name, p_id.GetText());
 }
@@ -49,15 +49,6 @@ bool MeshData::update_visibility(View3D *view3d)
   return ret;
 }
 
-Material *MeshData::material()
-{
-  Object *object = (Object *)id;
-  if (BKE_object_material_count_eval(object) == 0) {
-    return nullptr;
-  }
-  return BKE_object_material_get_eval(object, object->actcol);
-}
-
 pxr::HdMeshTopology MeshData::mesh_topology()
 {
   return pxr::HdMeshTopology(pxr::PxOsdOpenSubdivTokens->none,
@@ -88,6 +79,14 @@ pxr::HdPrimvarDescriptorVector MeshData::primvar_descriptors(pxr::HdInterpolatio
   return primvars;
 }
 
+pxr::SdfPath MeshData::material_id()
+{
+  if (!mat_data) {
+    return pxr::SdfPath();
+  }
+  return mat_data->p_id;
+}
+
 pxr::HdPrimvarDescriptorVector MeshData::instancer_primvar_descriptors(
     pxr::HdInterpolation interpolation)
 {
@@ -137,7 +136,7 @@ void MeshData::add_instance(DupliObject *dupli)
   if (instancer_id.IsEmpty()) {
     instancer_id = prim_id(scene_delegate, (Object *)id).AppendElementString("Instancer");
     scene_delegate->GetRenderIndex().InsertInstancer(scene_delegate, instancer_id);
-    CLOG_INFO(LOG_BSD, 2, "Instancer: %s, id=%s", name().c_str(), instancer_id.GetText());
+    CLOG_INFO(LOG_BSD, 2, "Instancer: %s, id=%s", id->name, instancer_id.GetText());
   }
   if (instances.empty()) {
     // USD hides the prototype mesh when instancing in contrary to the Blender, so we must add it
@@ -200,6 +199,26 @@ void MeshData::set_mesh(Mesh *mesh)
   }
 }
 
+void MeshData::set_material()
+{
+  Object *object = (Object *)id;
+  Material *mat = nullptr;
+  if (BKE_object_material_count_eval(object) > 0) {
+    mat = BKE_object_material_get_eval(object, object->actcol);
+  }
+
+  if (!mat) {
+    mat_data = nullptr;
+    return;
+  }
+  pxr::SdfPath id = MaterialData::prim_id(scene_delegate, mat);
+  mat_data = scene_delegate->material_data(id);
+  if (!mat_data) {
+    scene_delegate->materials[id] = MaterialData::create(scene_delegate, mat);
+    mat_data = scene_delegate->material_data(id);
+  }
+}
+
 void MeshData::init()
 {
   CLOG_INFO(LOG_BSD, 2, "%s", id->name);
@@ -217,7 +236,7 @@ void MeshData::init()
     BKE_object_to_mesh_clear(object);
   }
 
-  scene_delegate->set_material(*this);
+  set_material();
 }
 
 void MeshData::insert()
@@ -245,7 +264,6 @@ void MeshData::update()
   pxr::HdDirtyBits bits = pxr::HdChangeTracker::Clean;
   Object *object = (Object *)id;
   if ((id->recalc & ID_RECALC_GEOMETRY) || (((ID *)object->data)->recalc & ID_RECALC_GEOMETRY)) {
-    material_id = pxr::SdfPath::EmptyPath();
     instancer_id = pxr::SdfPath::EmptyPath();
     face_vertex_counts.clear();
     face_vertex_indices.clear();
@@ -258,7 +276,7 @@ void MeshData::update()
   }
   else {
     if (id->recalc & ID_RECALC_SHADING) {
-      scene_delegate->set_material(*this);
+      set_material();
       bits |= pxr::HdChangeTracker::DirtyMaterialId;
     }
     if (id->recalc & ID_RECALC_TRANSFORM) {
@@ -267,7 +285,6 @@ void MeshData::update()
   }
 
   if (!scene_delegate->GetRenderIndex().HasRprim(p_id)) {
-    /* Trying to insert prim */
     insert();
     return;
   }

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

@@ -9,6 +9,7 @@
 #include "BKE_duplilist.h"
 
 #include "object.h"
+#include "material.h"
 
 namespace blender::render::hydra {
 
@@ -23,9 +24,10 @@ class MeshData : public ObjectData {
   pxr::VtValue get_data(pxr::TfToken const &key) const override;
   bool update_visibility(View3D *view3d) override;
 
-  Material *material();
   pxr::HdMeshTopology mesh_topology();
   pxr::HdPrimvarDescriptorVector primvar_descriptors(pxr::HdInterpolation interpolation);
+  pxr::SdfPath material_id();
+
   pxr::HdPrimvarDescriptorVector instancer_primvar_descriptors(pxr::HdInterpolation interpolation);
   pxr::VtIntArray instance_indices();
   size_t sample_instancer_transform(size_t max_sample_count,
@@ -38,11 +40,11 @@ class MeshData : public ObjectData {
 
   void add_instance(DupliObject *dupli);
 
-  pxr::SdfPath material_id;
   pxr::SdfPath instancer_id;
 
  private:
   void set_mesh(Mesh *mesh);
+  void set_material();
 
   pxr::VtIntArray face_vertex_counts;
   pxr::VtIntArray face_vertex_indices;
@@ -51,6 +53,8 @@ class MeshData : public ObjectData {
   pxr::VtVec2fArray uvs;
 
   pxr::VtMatrix4dArray instances;
+
+  MaterialData *mat_data;
 };
 
 }  // namespace blender::render::hydra