When these features aren't used, there is no sense in storing the

corresponding data layers and using their values for computations.
Avoiding that should increase performance in many operations that
would otherwise have to read, write, or propagate these values.
It also means decreased memory usage-- not just for sculpt mode
but for any mesh that was in sculpt mode. Previously the mask, face set,
and hide status layers were *always* allocated by sculpt mode.

Here are a few basic tests when masking and face sets are not used:

| Test | Before | After |
| Subsurf Modifier | 148 ms | 126 ms |
| Sculpt Overlay Extraction | 24 ms every redraw | 0 ms |
| Memory usage | 252 MB | 236 MB |

I wouldn't expect any difference when they are used though.

The code changes are mostly just making sculpt features safe for when
the layers aren't stored, and some changes to the conversion to and
from the hide layers. Use of the ".hide_poly" attribute replaces testing
whether face sets are negative in many places.

Differential Revision: https://developer.blender.org/D15937

1 files changed, 1 insertions, 7 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_dyntopo.c b/source/blender/editors/sculpt_paint/sculpt_dyntopo.c
index ad8a1cde9dc..46674c5d239 100644
--- a/source/blender/editors/sculpt_paint/sculpt_dyntopo.c
+++ b/source/blender/editors/sculpt_paint/sculpt_dyntopo.c
@@ -215,13 +215,7 @@ static void SCULPT_dynamic_topology_disable_ex(
     BKE_sculptsession_bm_to_me(ob, true);
 
     /* Reset Face Sets as they are no longer valid. */
-    if (!CustomData_has_layer(&me->pdata, CD_SCULPT_FACE_SETS)) {
-      CustomData_add_layer(&me->pdata, CD_SCULPT_FACE_SETS, CD_SET_DEFAULT, NULL, me->totpoly);
-    }
-    ss->face_sets = CustomData_get_layer(&me->pdata, CD_SCULPT_FACE_SETS);
-    for (int i = 0; i < me->totpoly; i++) {
-      ss->face_sets[i] = 1;
-    }
+    CustomData_free_layers(&me->pdata, CD_SCULPT_FACE_SETS, me->totpoly);
     me->face_sets_color_default = 1;
 
     /* Sync the visibility to vertices manually as the pmap is still not initialized. */