Mesh: Remove unnecessary wrapper_type_finalize logic

After some discussions and investigation over the last couple months,
it's not clear what the "wrapper type finalize" logic is necessary for.
For edit meshes and regular meshes, normals are calculated lazily when
building the draw cache.

Apart from the unnecessary complication for mesh GPU draw data
extraction, this code also causes normals to always be calculated
when turning an edit mesh wrapper into a regular mesh. However, those
normals are immediately discarded since the edit deform cache is deleted
in the next line.

Beyond the obvious simplification, the motivation for this change is to
avoid requesting write access on the evaluated mesh and cage mesh. This
works better with implicit sharing, allowing other improvements.

Pull Request: https://projects.blender.org/blender/blender/pulls/120066

source/blender/blenkernel/BKE_mesh.h

@@ -494,9 +494,6 @@ bool BKE_mesh_validate_all_customdata(CustomData *vert_data,
 
 void BKE_mesh_strip_loose_faces(Mesh *mesh);
 
-/* In DerivedMesh.cc */
-void BKE_mesh_wrapper_deferred_finalize_mdata(Mesh *mesh_eval);
-
 /* **** Depsgraph evaluation **** */
 
 void BKE_mesh_eval_geometry(Depsgraph *depsgraph, Mesh *mesh);

source/blender/blenkernel/BKE_mesh_types.hh

@@ -163,11 +163,6 @@ struct MeshRuntime {
 
   /** #eMeshWrapperType and others. */
   eMeshWrapperType wrapper_type = ME_WRAPPER_TYPE_MDATA;
-  /**
-   * A type mask from wrapper_type,
-   * in case there are differences in finalizing logic between types.
-   */
-  eMeshWrapperType wrapper_type_finalize = ME_WRAPPER_TYPE_MDATA;
 
   /**
    * Settings for lazily evaluating the subdivision on the CPU if needed. These are

source/blender/blenkernel/intern/DerivedMesh.cc

@@ -89,8 +89,6 @@ using blender::bke::MeshComponent;
 #endif
 
 static void mesh_init_origspace(Mesh *mesh);
-static void editbmesh_calc_modifier_final_normals(Mesh *mesh_final);
-static void editbmesh_calc_modifier_final_normals_or_defer(Mesh *mesh_final);
 
 /* -------------------------------------------------------------------- */
 
@@ -465,16 +463,6 @@ static void mesh_calc_finalize(const Mesh *mesh_input, Mesh *mesh_eval)
   mesh_eval->runtime->edit_mesh = mesh_input->runtime->edit_mesh;
 }
 
-void BKE_mesh_wrapper_deferred_finalize_mdata(Mesh *mesh_eval)
-{
-  if (mesh_eval->runtime->wrapper_type_finalize & (1 << ME_WRAPPER_TYPE_BMESH)) {
-    editbmesh_calc_modifier_final_normals(mesh_eval);
-    mesh_eval->runtime->wrapper_type_finalize = eMeshWrapperType(
-        mesh_eval->runtime->wrapper_type_finalize & ~(1 << ME_WRAPPER_TYPE_BMESH));
-  }
-  BLI_assert(mesh_eval->runtime->wrapper_type_finalize == 0);
-}
-
 /**
  * Modifies the given mesh and geometry set. The mesh is not passed as part of the mesh component
  * in the \a geometry_set input, it is only passed in \a input_mesh and returned in the return
@@ -1001,36 +989,6 @@ bool editbmesh_modifier_is_enabled(const Scene *scene,
   return true;
 }
 
-static void editbmesh_calc_modifier_final_normals(Mesh *mesh_final)
-{
-  switch (mesh_final->runtime->wrapper_type) {
-    case ME_WRAPPER_TYPE_SUBD:
-    case ME_WRAPPER_TYPE_MDATA:
-      break;
-    case ME_WRAPPER_TYPE_BMESH: {
-      BMEditMesh &em = *mesh_final->runtime->edit_mesh;
-      blender::bke::EditMeshData &emd = *mesh_final->runtime->edit_data;
-      if (!emd.vert_positions.is_empty()) {
-        BKE_editmesh_cache_ensure_vert_normals(em, emd);
-        BKE_editmesh_cache_ensure_face_normals(em, emd);
-      }
-      return;
-    }
-  }
-}
-
-static void editbmesh_calc_modifier_final_normals_or_defer(Mesh *mesh_final)
-{
-  if (mesh_final->runtime->wrapper_type != ME_WRAPPER_TYPE_MDATA) {
-    /* Generated at draw time. */
-    mesh_final->runtime->wrapper_type_finalize = eMeshWrapperType(
-        1 << mesh_final->runtime->wrapper_type);
-    return;
-  }
-
-  editbmesh_calc_modifier_final_normals(mesh_final);
-}
-
 static MutableSpan<float3> mesh_wrapper_vert_coords_ensure_for_write(Mesh *mesh)
 {
   switch (mesh->runtime->wrapper_type) {
@@ -1244,12 +1202,6 @@ static void editbmesh_calc_modifiers(Depsgraph *depsgraph,
     BKE_id_free(nullptr, mesh_orco);
   }
 
-  /* Compute normals. */
-  editbmesh_calc_modifier_final_normals_or_defer(mesh_final);
-  if (mesh_cage && (mesh_cage != mesh_final)) {
-    editbmesh_calc_modifier_final_normals_or_defer(mesh_cage);
-  }
-
   /* Return final mesh. */
   *r_final = mesh_final;
   if (r_cage) {

source/blender/blenkernel/intern/mesh.cc

@@ -113,7 +113,6 @@ static void mesh_copy_data(Main *bmain,
   mesh_dst->runtime = new blender::bke::MeshRuntime();
   mesh_dst->runtime->deformed_only = mesh_src->runtime->deformed_only;
   mesh_dst->runtime->wrapper_type = mesh_src->runtime->wrapper_type;
-  mesh_dst->runtime->wrapper_type_finalize = mesh_src->runtime->wrapper_type_finalize;
   mesh_dst->runtime->subsurf_runtime_data = mesh_src->runtime->subsurf_runtime_data;
   mesh_dst->runtime->cd_mask_extra = mesh_src->runtime->cd_mask_extra;
   /* Copy face dot tags and edge tags, since meshes may be duplicated after a subsurf modifier or

source/blender/blenkernel/intern/mesh_wrapper.cc

@@ -129,10 +129,6 @@ void BKE_mesh_wrapper_ensure_mdata(Mesh *mesh)
           mesh->runtime->is_original_bmesh = false;
         }
 
-        if (mesh->runtime->wrapper_type_finalize) {
-          BKE_mesh_wrapper_deferred_finalize_mdata(mesh);
-        }
-
         mesh->runtime->edit_data.reset();
         break;
       }