Refactor: Sculpt: Remove SculptSession face visibility pointer

Part of #118145.

source/blender/blenkernel/BKE_paint.hh

@@ -354,12 +354,6 @@ struct SculptSession : blender::NonCopyable, blender::NonMovable {
   blender::Array<int> vert_to_edge_indices;
   blender::GroupedSpan<int> vert_to_edge_map;
 
-  /**
-   * A reference to the ".hide_poly" attribute, to store whether (base) faces are hidden.
-   * May be null.
-   */
-  const bool *hide_poly = nullptr;
-
   /* BMesh for dynamic topology sculpting */
   BMesh *bm = nullptr;
   /* Undo/redo log for dynamic topology sculpting */
@@ -550,11 +544,6 @@ void BKE_sculpt_update_object_after_eval(Depsgraph *depsgraph, Object *ob_eval);
  * it's the last modifier on the stack and it is not on the first level.
  */
 MultiresModifierData *BKE_sculpt_multires_active(const Scene *scene, Object *ob);
-/**
- * Update the pointer to the ".hide_poly" attribute. This is necessary because it is dynamically
- * created, removed, and made mutable.
- */
-void BKE_sculpt_hide_poly_pointer_update(Object &object);
 
 /**
  * Ensures a mask layer exists. If depsgraph and bmain are non-null,

source/blender/blenkernel/intern/paint.cc

@@ -1994,9 +1994,6 @@ static void sculpt_update_object(Depsgraph *depsgraph,
     ss.multires.level = 0;
   }
 
-  ss.hide_poly = (bool *)CustomData_get_layer_named(
-      &mesh_orig->face_data, CD_PROP_BOOL, ".hide_poly");
-
   ss.subdiv_ccg = mesh_eval->runtime->subdiv_ccg.get();
 
   pbvh::Tree &pbvh = object::pbvh_ensure(*depsgraph, *ob);
@@ -2196,13 +2193,6 @@ void BKE_sculpt_update_object_for_edit(Depsgraph *depsgraph, Object *ob_orig, bo
   sculpt_update_object(depsgraph, ob_orig, ob_eval, is_paint_tool);
 }
 
-void BKE_sculpt_hide_poly_pointer_update(Object &object)
-{
-  const Mesh &mesh = *static_cast<const Mesh *>(object.data);
-  object.sculpt->hide_poly = static_cast<const bool *>(
-      CustomData_get_layer_named(&mesh.face_data, CD_PROP_BOOL, ".hide_poly"));
-}
-
 void BKE_sculpt_mask_layers_ensure(Depsgraph *depsgraph,
                                    Main *bmain,
                                    Object *ob,

source/blender/editors/sculpt_paint/sculpt.cc

@@ -610,12 +610,14 @@ static void vertex_neighbors_get_faces(const Object &object,
   const OffsetIndices<int> faces = mesh.faces();
   const Span<int> corner_verts = mesh.corner_verts();
   const GroupedSpan<int> vert_to_face_map = mesh.vert_to_face_map();
+  const bke::AttributeAccessor attributes = mesh.attributes();
+  const VArraySpan hide_poly = *attributes.lookup<bool>(".hide_poly", bke::AttrDomain::Face);
   iter->num_duplicates = 0;
   iter->neighbors.clear();
   iter->neighbor_indices.clear();
 
   for (const int face_i : vert_to_face_map[vertex.i]) {
-    if (ss.hide_poly && ss.hide_poly[face_i]) {
+    if (!hide_poly.is_empty() && hide_poly[face_i]) {
       /* Skip connectivity from hidden faces. */
       continue;
     }
@@ -731,11 +733,9 @@ bool vert_is_boundary(const Object &object, const PBVHVertRef vertex)
     case bke::pbvh::Type::Mesh: {
       const Mesh &mesh = *static_cast<const Mesh *>(object.data);
       const GroupedSpan<int> vert_to_face_map = mesh.vert_to_face_map();
-      if (!hide::vert_all_faces_visible_get(ss.hide_poly ? Span(ss.hide_poly, ss.faces_num) :
-                                                           Span<bool>(),
-                                            vert_to_face_map,
-                                            vertex.i))
-      {
+      const bke::AttributeAccessor attributes = mesh.attributes();
+      const VArraySpan hide_poly = *attributes.lookup<bool>(".hide_poly", bke::AttrDomain::Face);
+      if (!hide::vert_all_faces_visible_get(hide_poly, vert_to_face_map, vertex.i)) {
         return true;
       }
       return check_boundary_vert_in_base_mesh(ss, vertex.i);

source/blender/editors/sculpt_paint/sculpt_face_set.cc

@@ -1042,7 +1042,6 @@ static int change_visibility_exec(bContext *C, wmOperator *op)
   undo::push_end(object);
 
   bke::pbvh::update_visibility(object, pbvh);
-  BKE_sculpt_hide_poly_pointer_update(object);
 
   islands::invalidate(*object.sculpt);
   hide::tag_update_visibility(*C);

source/blender/editors/sculpt_paint/sculpt_undo.cc

@@ -631,7 +631,6 @@ static void restore_hidden_face(Object &object, Node &unode, MutableSpan<bool> m
     }
   }
   hide_poly.finish();
-  BKE_sculpt_hide_poly_pointer_update(object);
 }
 
 static void restore_color(Object &object, StepData &step_data, MutableSpan<bool> modified_vertices)