Fix: Write hide status attributes for undo steps

We don't convert to the old mesh format when writing undo steps to
avoid overhead. So we can't skip writing the hide attributes then.

3 files changed, 10 insertions, 6 deletions

diff --git a/source/blender/blenkernel/BKE_customdata.h b/source/blender/blenkernel/BKE_customdata.h
index 2ced685884b..6461ff30cd6 100644
--- a/source/blender/blenkernel/BKE_customdata.h
+++ b/source/blender/blenkernel/BKE_customdata.h
@@ -718,7 +718,7 @@ void CustomData_data_transfer(const struct MeshPairRemap *me_remap,
  */
 void CustomData_blend_write_prepare(CustomData &data,
                                     blender::Vector<CustomDataLayer, 16> &layers_to_write,
-                                    const blender::Set<blender::StringRef> &skip_names = {});
+                                    const blender::Set<std::string> &skip_names = {});
 
 /**
  * \param layers_to_write: Layers created by #CustomData_blend_write_prepare.
diff --git a/source/blender/blenkernel/intern/customdata.cc b/source/blender/blenkernel/intern/customdata.cc
index 69825031795..90bc79f6907 100644
--- a/source/blender/blenkernel/intern/customdata.cc
+++ b/source/blender/blenkernel/intern/customdata.cc
@@ -4355,7 +4355,7 @@ void CustomData_file_write_info(int type, const char **r_struct_name, int *r_str
 
 void CustomData_blend_write_prepare(CustomData &data,
                                     Vector<CustomDataLayer, 16> &layers_to_write,
-                                    const Set<StringRef> &skip_names)
+                                    const Set<std::string> &skip_names)
 {
   for (const CustomDataLayer &layer : Span(data.layers, data.totlayer)) {
     if (layer.flag & CD_FLAG_NOCOPY) {
diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index 1b8d094e9d3..7f2c09f049b 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -212,6 +212,7 @@ static void mesh_foreach_path(ID *id, BPathForeachPathData *bpath_data)
 
 static void mesh_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
+  using namespace blender;
   Mesh *mesh = (Mesh *)id;
   const bool is_undo = BLO_write_is_undo(writer);
 
@@ -245,14 +246,17 @@ static void mesh_blend_write(BlendWriter *writer, ID *id, const void *id_address
     memset(&mesh->pdata, 0, sizeof(mesh->pdata));
   }
   else {
+    Set<std::string> names_to_skip;
     if (!BLO_write_is_undo(writer)) {
       BKE_mesh_legacy_convert_hide_layers_to_flags(mesh);
+      /* When converting to the old mesh format, don't save redunant attributes. */
+      names_to_skip.add_multiple_new({".hide_vert", ".hide_edge", ".hide_poly"});
     }
 
-    CustomData_blend_write_prepare(mesh->vdata, vert_layers, {".hide_vert"});
-    CustomData_blend_write_prepare(mesh->edata, edge_layers, {".hide_edge"});
-    CustomData_blend_write_prepare(mesh->ldata, loop_layers);
-    CustomData_blend_write_prepare(mesh->pdata, poly_layers, {".hide_poly"});
+    CustomData_blend_write_prepare(mesh->vdata, vert_layers, names_to_skip);
+    CustomData_blend_write_prepare(mesh->edata, edge_layers, names_to_skip);
+    CustomData_blend_write_prepare(mesh->ldata, loop_layers, names_to_skip);
+    CustomData_blend_write_prepare(mesh->pdata, poly_layers, names_to_skip);
   }
 
   BLO_write_id_struct(writer, Mesh, id_address, &mesh->id);