Sculpt: Use mpoly flags to sync Face Sets visibility

Previously, all Face Set visibility logic was using mvert flags directly
to store the visibility state on the vertices while sculpting. As Face
Sets are a poly attribute, it is much simpler to use mpoly flags and let
BKE_mesh_flush_hidden_from_polys handle the vertex visibility, even for
Multires.

Now all operators that update the Face Set visibility state will always
copy the visibility to the mesh (using poly flags) and the grids, all
using the same code.

This should fix a lot of visibility glitches and bugs like the following:
 - Sculpt visibility reset when changing multires levels.
 - Multires visibility not updating in edit mode.
 - Single face visibible when surrounded by visibile face set, even when
the face set was hidden.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9175

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_paint.h b/source/blender/blenkernel/BKE_paint.h
index 0d3241ba6b8..150d0d9b011 100644
--- a/source/blender/blenkernel/BKE_paint.h
+++ b/source/blender/blenkernel/BKE_paint.h
@@ -612,6 +612,11 @@ void BKE_sculpt_bvh_update_from_ccg(struct PBVH *pbvh, struct SubdivCCG *subdiv_
  * updated according to the face sets. */
 void BKE_sculpt_sync_face_set_visibility(struct Mesh *mesh, struct SubdivCCG *subdiv_ccg);
 
+/* Individual function to sync the Face Set visibility to mesh and grids. */
+void BKE_sculpt_sync_face_sets_visibility_to_base_mesh(struct Mesh *mesh);
+void BKE_sculpt_sync_face_sets_visibility_to_grids(struct Mesh *mesh,
+                                                   struct SubdivCCG *subdiv_ccg);
+
 /* Ensures that a Face Set data-layers exists. If it does not, it creates one respecting the
  * visibility stored in the vertices of the mesh. If it does, it copies the visibility from the
  * mesh to the Face Sets. */