Mesh: Avoid unnecessary normal calculation and dirty tags

This is mostly a cleanup to avoid hardcoding the eager calculation of
normals it isn't necessary, by reducing calls to `BKE_mesh_calc_normals`
and by removing calls to `BKE_mesh_normals_tag_dirty` when the mesh
is newly created and already has dirty normals anyway. This reduces
boilerplate code and makes the "dirty by default" state more clear.
Any regressions from this commit should be easy to fix, though the
lazy calculation is solid enough that none are expected.

1 files changed, 4 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index 25d97d0bd3c..7f005fda6a5 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -1112,6 +1112,9 @@ Mesh *BKE_mesh_new_nomain_from_template_ex(const Mesh *me_src,
   mesh_ensure_cdlayers_primary(me_dst, do_tessface);
   BKE_mesh_update_customdata_pointers(me_dst, false);
 
+  /* Expect that normals aren't copied at all, since the destination mesh is new. */
+  BLI_assert(BKE_mesh_vertex_normals_are_dirty(me_dst));
+
   return me_dst;
 }
 
@@ -1688,6 +1691,7 @@ void BKE_mesh_transform(Mesh *me, const float mat[4][4], bool do_keys)
       mul_m3_v3(m3, *lnors);
     }
   }
+  BKE_mesh_normals_tag_dirty(me);
 }
 
 void BKE_mesh_translate(Mesh *me, const float offset[3], const bool do_keys)