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.

3 files changed, 4 insertions, 7 deletions

diff --git a/source/blender/editors/mesh/editmesh_mask_extract.c b/source/blender/editors/mesh/editmesh_mask_extract.c
index d3fc83eedd7..7634ce6af9e 100644
--- a/source/blender/editors/mesh/editmesh_mask_extract.c
+++ b/source/blender/editors/mesh/editmesh_mask_extract.c
@@ -230,8 +230,6 @@ static int geometry_extract_apply(bContext *C,
     }
   }
 
-  BKE_mesh_calc_normals(new_ob->data);
-
   WM_event_add_notifier(C, NC_OBJECT | ND_MODIFIER, new_ob);
   BKE_mesh_batch_cache_dirty_tag(new_ob->data, BKE_MESH_BATCH_DIRTY_ALL);
   DEG_relations_tag_update(bmain);
@@ -551,7 +549,6 @@ static int paint_mask_slice_exec(bContext *C, wmOperator *op)
     CustomData_free_layers(&new_ob_mesh->vdata, CD_PAINT_MASK, new_ob_mesh->totvert);
 
     BKE_mesh_nomain_to_mesh(new_ob_mesh, new_ob->data, new_ob, &CD_MASK_MESH, true);
-    BKE_mesh_calc_normals(new_ob->data);
     BKE_mesh_copy_parameters_for_eval(new_ob->data, mesh);
     WM_event_add_notifier(C, NC_OBJECT | ND_MODIFIER, new_ob);
     BKE_mesh_batch_cache_dirty_tag(new_ob->data, BKE_MESH_BATCH_DIRTY_ALL);
@@ -561,7 +558,6 @@ static int paint_mask_slice_exec(bContext *C, wmOperator *op)
   }
 
   BKE_mesh_nomain_to_mesh(new_mesh, ob->data, ob, &CD_MASK_MESH, true);
-  BKE_mesh_calc_normals(ob->data);
 
   if (ob->mode == OB_MODE_SCULPT) {
     SculptSession *ss = ob->sculpt;
diff --git a/source/blender/editors/mesh/mesh_data.c b/source/blender/editors/mesh/mesh_data.c
index 6f5c9d410c7..f6f4260b762 100644
--- a/source/blender/editors/mesh/mesh_data.c
+++ b/source/blender/editors/mesh/mesh_data.c
@@ -1092,7 +1092,8 @@ void ED_mesh_update(Mesh *mesh, bContext *C, bool calc_edges, bool calc_edges_lo
   /* Default state is not to have tessface's so make sure this is the case. */
   BKE_mesh_tessface_clear(mesh);
 
-  BKE_mesh_calc_normals(mesh);
+  /* Tag lazily calculated data as dirty. */
+  BKE_mesh_normals_tag_dirty(mesh);
 
   DEG_id_tag_update(&mesh->id, 0);
   WM_event_add_notifier(C, NC_GEOM | ND_DATA, mesh);
diff --git a/source/blender/editors/mesh/meshtools.c b/source/blender/editors/mesh/meshtools.c
index d57471b658c..9575fde68f0 100644
--- a/source/blender/editors/mesh/meshtools.c
+++ b/source/blender/editors/mesh/meshtools.c
@@ -681,8 +681,8 @@ int ED_mesh_join_objects_exec(bContext *C, wmOperator *op)
   /* tessface data removed above, no need to update */
   BKE_mesh_update_customdata_pointers(me, false);
 
-  /* update normals in case objects with non-uniform scale are joined */
-  BKE_mesh_calc_normals(me);
+  /* Tag normals dirty because vertex positions could be changed from the original. */
+  BKE_mesh_normals_tag_dirty(me);
 
   /* old material array */
   for (a = 1; a <= ob->totcol; a++) {