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, 6 deletions

diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index 1048ca39958..ef57c9a2e0e 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -292,13 +292,10 @@ struct Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
                                                   bool build_shapekey_layers);
 
 /**
- * Copies a nomain-Mesh into an existing Mesh.
+ * Move data from a mesh outside of the main data-base into a mesh in the data-base.
+ * Takes ownership of the source mesh.
  */
-void BKE_mesh_nomain_to_mesh(struct Mesh *mesh_src,
-                             struct Mesh *mesh_dst,
-                             struct Object *ob,
-                             const struct CustomData_MeshMasks *mask,
-                             bool take_ownership);
+void BKE_mesh_nomain_to_mesh(struct Mesh *mesh_src, struct Mesh *mesh_dst, struct Object *ob);
 void BKE_mesh_nomain_to_meshkey(struct Mesh *mesh_src, struct Mesh *mesh_dst, struct KeyBlock *kb);
 
 /* vertex level transformations & checks (no derived mesh) */