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

@@ -122,6 +122,18 @@ bool BlenderSceneDelegate::GetVisible(pxr::SdfPath const &id)
   return object_data(id)->visible;
 }
 
+bool BlenderSceneDelegate::GetDoubleSided(pxr::SdfPath const &id)
+{
+  CLOG_INFO(LOG_RENDER_HYDRA_SCENE, 3, "%s", id.GetText());
+  return mesh_data(id)->double_sided();
+}
+
+pxr::HdCullStyle BlenderSceneDelegate::GetCullStyle(pxr::SdfPath const &id)
+{
+  CLOG_INFO(LOG_RENDER_HYDRA_SCENE, 3, "%s", id.GetText());
+  return mesh_data(id)->cull_style;
+}
+
 pxr::SdfPath BlenderSceneDelegate::GetInstancerId(pxr::SdfPath const &prim_id)
 {
   CLOG_INFO(LOG_RENDER_HYDRA_SCENE, 3, "%s", prim_id.GetText());

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

@@ -43,6 +43,8 @@ class BlenderSceneDelegate : public pxr::HdSceneDelegate {
   pxr::SdfPath GetMaterialId(pxr::SdfPath const &rprim_id) override;
   pxr::VtValue GetMaterialResource(pxr::SdfPath const &material_id) override;
   bool GetVisible(pxr::SdfPath const &id) override;
+  bool GetDoubleSided(pxr::SdfPath const &id) override;
+  pxr::HdCullStyle GetCullStyle(pxr::SdfPath const &id) override;
   pxr::SdfPath GetInstancerId(pxr::SdfPath const &prim_id) override;
   pxr::SdfPathVector GetInstancerPrototypes(pxr::SdfPath const &instancer_id) override;
   pxr::VtIntArray GetInstanceIndices(pxr::SdfPath const &instancer_id,

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

@@ -30,7 +30,7 @@ MaterialData::MaterialData(BlenderSceneDelegate *scene_delegate,
 void MaterialData::init()
 {
   ID_LOG(2, "");
-
+  double_sided = (((Material *)id)->blend_flag & MA_BL_CULL_BACKFACE) == 0;
   material_network_map_ = pxr::VtValue();
 
   /* Call of python function hydra.export_mtlx() */
@@ -120,9 +120,13 @@ void MaterialData::remove()
 void MaterialData::update()
 {
   ID_LOG(2, "");
+  bool prev_double_sided = double_sided;
   init();
   scene_delegate_->GetRenderIndex().GetChangeTracker().MarkSprimDirty(prim_id,
                                                                       pxr::HdMaterial::AllDirty);
+  if (prev_double_sided != double_sided) {
+
+  }
 }
 
 pxr::VtValue MaterialData::get_data(pxr::TfToken const &key) const

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

@@ -27,6 +27,8 @@ class MaterialData : public IdData {
   pxr::VtValue get_data(pxr::TfToken const &key) const override;
   pxr::VtValue get_material_resource() const;
 
+  bool double_sided = true;
+
  private:
   pxr::SdfAssetPath mtlx_path_;
   pxr::VtValue material_network_map_;

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

@@ -74,7 +74,7 @@ void MeshData::update()
   else {
     if (id->recalc & ID_RECALC_SHADING) {
       write_material();
-      bits |= pxr::HdChangeTracker::DirtyMaterialId;
+      bits |= pxr::HdChangeTracker::DirtyMaterialId | pxr::HdChangeTracker::DirtyDoubleSided;
     }
     if (id->recalc & ID_RECALC_TRANSFORM) {
       write_transform();
@@ -164,6 +164,14 @@ pxr::SdfPath MeshData::material_id() const
   return mat_data_->prim_id;
 }
 
+bool MeshData::double_sided() const
+{
+  if (mat_data_) {
+    return mat_data_->double_sided;
+  }
+  return true;
+}
+
 void MeshData::write_mesh(Mesh *mesh)
 {
   face_vertex_counts_.clear();

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

@@ -28,6 +28,9 @@ class MeshData : public ObjectData {
   pxr::HdMeshTopology mesh_topology() const;
   pxr::HdPrimvarDescriptorVector primvar_descriptors(pxr::HdInterpolation interpolation) const;
   pxr::SdfPath material_id() const;
+  bool double_sided() const;
+
+  pxr::HdCullStyle cull_style = pxr::HdCullStyleBackUnlessDoubleSided;
 
  private:
   void write_mesh(Mesh *mesh);