Cleanup: Simplify BKE_mesh_nomain_to_mesh

- Remove "take ownership" argument which was confusing and always true
  - The argument made ownership very confusing
  - Better to avoid boolean arguments that switch a function's purpose
- Remove "mask" argument which was basically wrong and not used properly
  - "EVERYTHING" was used because developers are wary of removing data
  - Instead use `CD_MASK_MESH` for its purpose of original mesh data
- Remove use of shallow copied temporary mesh, which is unnecessary now
- Split shape key processing into separate functions and use C++ types
- Copy fields explicitly rather than using memcpy for the whole struct
- Use higher level functions and avoid redundant code
  - The whole idea is pretty simple and can be built from standard logic
- Adjust `CustomData` logic to be consistent with "assign" expectations
  - Clear the layer data from the source, and moves the anonymous ID

Differential Revision: https://developer.blender.org/D15857

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index 8254bb953d2..c82d9be008d 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -881,11 +881,12 @@ static void mesh_clear_geometry(Mesh *mesh)
   mesh->totpoly = 0;
   mesh->act_face = -1;
   mesh->totselect = 0;
+
+  BLI_freelistN(&mesh->vertex_group_names);
 }
 
 void BKE_mesh_clear_geometry(Mesh *mesh)
 {
-  BKE_animdata_free(&mesh->id, false);
   BKE_mesh_runtime_clear_cache(mesh);
   mesh_clear_geometry(mesh);
 }
@@ -975,6 +976,7 @@ void BKE_mesh_copy_parameters(Mesh *me_dst, const Mesh *me_src)
   copy_v3_v3(me_dst->size, me_src->size);
 
   me_dst->vertex_group_active_index = me_src->vertex_group_active_index;
+  me_dst->attributes_active_index = me_src->attributes_active_index;
 }
 
 void BKE_mesh_copy_parameters_for_eval(Mesh *me_dst, const Mesh *me_src)