Mesh: Move selection flags to generic attributes

Using the attribute name semantics from T97452, this patch moves the
selection status of mesh elements from the `SELECT` of vertices, and
edges, and the `ME_FACE_SEL` of faces to generic boolean attribute
Storing this data as generic attributes can significantly simplify and
improve code, as described in T95965.

The attributes are called `.select_vert`, `.select_edge`, and
`.select_poly`. The `.` prefix means they are "UI attributes",so they
still contain original data edited by users, but they aren't meant to
be accessed procedurally by the user in arbitrary situations. They are
also be hidden in the spreadsheet and the attribute list.

Until 4.0, the attributes are still written to and read from the mesh
in the old way, so neither forward nor backward compatibility are
affected. This means memory requirements will be increased by one byte
per element when selection is used. When the flags are removed
completely, requirements will decrease.

Further notes:
* The `MVert` flag is empty at runtime now, so it can be ignored.
* `BMesh` is unchanged, otherwise the change would be much larger.
* Many tests have slightly different results, since the selection
  attribute uses more generic propagation. Previously you couldn't
  really rely on edit mode selections being propagated procedurally.
  Now it mostly works as expected.

Similar to 2480b55f216c
Ref T95965

Differential Revision: https://developer.blender.org/D15795

11 files changed, 479 insertions, 339 deletions

diff --git a/source/blender/editors/armature/armature_skinning.c b/source/blender/editors/armature/armature_skinning.c
index e39cc157c19..6155aac621d 100644
--- a/source/blender/editors/armature/armature_skinning.c
+++ b/source/blender/editors/armature/armature_skinning.c
@@ -203,10 +203,13 @@ static void envelope_bone_weighting(Object *ob,
     use_mask = true;
   }
 
+  const bool *select_vert = (const bool *)CustomData_get_layer_named(
+      &mesh->vdata, CD_PROP_BOOL, ".select_vert");
+
   /* for each vertex in the mesh */
-  const MVert *mesh_verts = BKE_mesh_verts(mesh);
   for (int i = 0; i < mesh->totvert; i++) {
-    if (use_mask && !(mesh_verts[i].flag & SELECT)) {
+
+    if (use_mask && !(select_vert && select_vert[i])) {
       continue;
     }
 
diff --git a/source/blender/editors/armature/meshlaplacian.c b/source/blender/editors/armature/meshlaplacian.c
index 904e6213466..567977e51c4 100644
--- a/source/blender/editors/armature/meshlaplacian.c
+++ b/source/blender/editors/armature/meshlaplacian.c
@@ -669,17 +669,25 @@ void heat_bone_weighting(Object *ob,
 
     /*  (added selectedVerts content for vertex mask, they used to just equal 1) */
     if (use_vert_sel) {
-      for (a = 0, mp = polys; a < me->totpoly; mp++, a++) {
-        for (j = 0, ml = loops + mp->loopstart; j < mp->totloop; j++, ml++) {
-          mask[ml->v] = (mesh_verts[ml->v].flag & SELECT) != 0;
+      const bool *select_vert = (const bool *)CustomData_get_layer_named(
+          &me->vdata, CD_PROP_BOOL, ".select_vert");
+      if (select_vert) {
+        for (a = 0, mp = polys; a < me->totpoly; mp++, a++) {
+          for (j = 0, ml = loops + mp->loopstart; j < mp->totloop; j++, ml++) {
+            mask[ml->v] = select_vert[ml->v];
+          }
         }
       }
     }
     else if (use_face_sel) {
-      for (a = 0, mp = polys; a < me->totpoly; mp++, a++) {
-        if (mp->flag & ME_FACE_SEL) {
-          for (j = 0, ml = loops + mp->loopstart; j < mp->totloop; j++, ml++) {
-            mask[ml->v] = 1;
+      const bool *select_poly = (const bool *)CustomData_get_layer_named(
+          &me->pdata, CD_PROP_BOOL, ".select_poly");
+      if (select_poly) {
+        for (a = 0, mp = polys; a < me->totpoly; mp++, a++) {
+          if (select_poly[a]) {
+            for (j = 0, ml = loops + mp->loopstart; j < mp->totloop; j++, ml++) {
+              mask[ml->v] = 1;
+            }
           }
         }
       }
diff --git a/source/blender/editors/mesh/editface.cc b/source/blender/editors/mesh/editface.cc
index f729db29b8c..ac8dd87bed6 100644
--- a/source/blender/editors/mesh/editface.cc
+++ b/source/blender/editors/mesh/editface.cc
@@ -73,14 +73,9 @@ void paintface_flush_flags(bContext *C,
   Mesh *me_eval = (Mesh *)ob_eval->runtime.data_eval;
   bke::MutableAttributeAccessor attributes_eval = me_eval->attributes_for_write();
   bool updated = false;
-  const Span<MPoly> me_polys = me->polys();
 
   if (me_orig != nullptr && me_eval != nullptr && me_orig->totpoly == me->totpoly) {
     /* Update the COW copy of the mesh. */
-    MutableSpan<MPoly> orig_polys = me_orig->polys_for_write();
-    for (int i = 0; i < me->totpoly; i++) {
-      orig_polys[i].flag = me_polys[i].flag;
-    }
     if (flush_hidden) {
       const VArray<bool> hide_poly_me = attributes_me.lookup_or_default<bool>(
           ".hide_poly", ATTR_DOMAIN_FACE, false);
@@ -89,28 +84,46 @@ void paintface_flush_flags(bContext *C,
       hide_poly_me.materialize(hide_poly_orig.span);
       hide_poly_orig.finish();
     }
+    if (flush_selection) {
+      const VArray<bool> select_poly_me = attributes_me.lookup_or_default<bool>(
+          ".select_poly", ATTR_DOMAIN_FACE, false);
+      bke::SpanAttributeWriter<bool> select_poly_orig =
+          attributes_orig.lookup_or_add_for_write_only_span<bool>(".select_poly",
+                                                                  ATTR_DOMAIN_FACE);
+      select_poly_me.materialize(select_poly_orig.span);
+      select_poly_orig.finish();
+    }
 
     /* Mesh polys => Final derived polys */
     if ((index_array = (const int *)CustomData_get_layer(&me_eval->pdata, CD_ORIGINDEX))) {
-      MutableSpan<MPoly> eval_polys = me_orig->polys_for_write();
-      /* loop over final derived polys */
-      for (const int i : eval_polys.index_range()) {
-        if (index_array[i] != ORIGINDEX_NONE) {
-          /* Copy flags onto the final derived poly from the original mesh poly */
-          eval_polys[i].flag = me_polys[index_array[i]].flag;
+      if (flush_hidden) {
+        const VArray<bool> hide_poly_orig = attributes_orig.lookup_or_default<bool>(
+            ".hide_poly", ATTR_DOMAIN_FACE, false);
+        bke::SpanAttributeWriter<bool> hide_poly_eval =
+            attributes_eval.lookup_or_add_for_write_only_span<bool>(".hide_poly",
+                                                                    ATTR_DOMAIN_FACE);
+        for (const int i : IndexRange(me_eval->totpoly)) {
+          const int orig_poly_index = index_array[i];
+          if (orig_poly_index != ORIGINDEX_NONE) {
+            hide_poly_eval.span[i] = hide_poly_orig[orig_poly_index];
+          }
         }
+        hide_poly_eval.finish();
       }
-      const VArray<bool> hide_poly_orig = attributes_orig.lookup_or_default<bool>(
-          ".hide_poly", ATTR_DOMAIN_FACE, false);
-      bke::SpanAttributeWriter<bool> hide_poly_eval =
-          attributes_eval.lookup_or_add_for_write_only_span<bool>(".hide_poly", ATTR_DOMAIN_FACE);
-      for (const int i : IndexRange(me_eval->totpoly)) {
-        const int orig_poly_index = index_array[i];
-        if (orig_poly_index != ORIGINDEX_NONE) {
-          hide_poly_eval.span[i] = hide_poly_orig[orig_poly_index];
+      if (flush_selection) {
+        const VArray<bool> select_poly_orig = attributes_orig.lookup_or_default<bool>(
+            ".select_poly", ATTR_DOMAIN_FACE, false);
+        bke::SpanAttributeWriter<bool> select_poly_eval =
+            attributes_eval.lookup_or_add_for_write_only_span<bool>(".select_poly",
+                                                                    ATTR_DOMAIN_FACE);
+        for (const int i : IndexRange(me_eval->totpoly)) {
+          const int orig_poly_index = index_array[i];
+          if (orig_poly_index != ORIGINDEX_NONE) {
+            select_poly_eval.span[i] = select_poly_orig[orig_poly_index];
+          }
         }
+        select_poly_eval.finish();
       }
-      hide_poly_eval.finish();
 
       updated = true;
     }
@@ -141,25 +154,26 @@ void paintface_hide(bContext *C, Object *ob, const bool unselected)
     return;
   }
 
-  MutableSpan<MPoly> polys = me->polys_for_write();
   bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   bke::SpanAttributeWriter<bool> hide_poly = attributes.lookup_or_add_for_write_span<bool>(
       ".hide_poly", ATTR_DOMAIN_FACE);
+  bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
 
   for (int i = 0; i < me->totpoly; i++) {
-    MPoly *mpoly = &polys[i];
     if (!hide_poly.span[i]) {
-      if (((mpoly->flag & ME_FACE_SEL) == 0) == unselected) {
+      if (!select_poly.span[i] == unselected) {
         hide_poly.span[i] = true;
       }
     }
 
     if (hide_poly.span[i]) {
-      mpoly->flag &= ~ME_FACE_SEL;
+      select_poly.span[i] = false;
     }
   }
 
   hide_poly.finish();
+  select_poly.finish();
 
   BKE_mesh_flush_hidden_from_polys(me);
 
@@ -174,18 +188,19 @@ void paintface_reveal(bContext *C, Object *ob, const bool select)
     return;
   }
 
-  MutableSpan<MPoly> polys = me->polys_for_write();
   bke::MutableAttributeAccessor attributes = me->attributes_for_write();
 
   if (select) {
     const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
         ".hide_poly", ATTR_DOMAIN_FACE, false);
-    for (int i = 0; i < me->totpoly; i++) {
-      MPoly *mpoly = &polys[i];
+    bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+        ".select_poly", ATTR_DOMAIN_FACE);
+    for (const int i : hide_poly.index_range()) {
       if (hide_poly[i]) {
-        mpoly->flag |= ME_FACE_SEL;
+        select_poly.span[i] = true;
       }
     }
+    select_poly.finish();
   }
 
   attributes.remove(".hide_poly");
@@ -207,27 +222,29 @@ static void select_linked_tfaces_with_seams(Mesh *me, const uint index, const bo
   BLI_bitmap *poly_tag = BLI_BITMAP_NEW(me->totpoly, __func__);
 
   const Span<MEdge> edges = me->edges();
-  MutableSpan<MPoly> polys = me->polys_for_write();
+  const Span<MPoly> polys = me->polys();
   const Span<MLoop> loops = me->loops();
-  bke::AttributeAccessor attributes = me->attributes();
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
       ".hide_poly", ATTR_DOMAIN_FACE, false);
+  bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
 
   if (index != (uint)-1) {
     /* only put face under cursor in array */
-    const MPoly *mp = &polys[index];
-    BKE_mesh_poly_edgebitmap_insert(edge_tag, mp, &loops[mp->loopstart]);
+    const MPoly &poly = polys[index];
+    BKE_mesh_poly_edgebitmap_insert(edge_tag, &poly, &loops[poly.loopstart]);
     BLI_BITMAP_ENABLE(poly_tag, index);
   }
   else {
     /* fill array by selection */
     for (int i = 0; i < me->totpoly; i++) {
-      MPoly *mp = &polys[i];
       if (hide_poly[i]) {
         /* pass */
       }
-      else if (mp->flag & ME_FACE_SEL) {
-        BKE_mesh_poly_edgebitmap_insert(edge_tag, mp, &loops[mp->loopstart]);
+      else if (select_poly.span[i]) {
+        const MPoly &poly = polys[i];
+        BKE_mesh_poly_edgebitmap_insert(edge_tag, &poly, &loops[poly.loopstart]);
         BLI_BITMAP_ENABLE(poly_tag, i);
       }
     }
@@ -238,7 +255,6 @@ static void select_linked_tfaces_with_seams(Mesh *me, const uint index, const bo
 
     /* expand selection */
     for (int i = 0; i < me->totpoly; i++) {
-      MPoly *mp = &polys[i];
       if (hide_poly[i]) {
         continue;
       }
@@ -246,8 +262,9 @@ static void select_linked_tfaces_with_seams(Mesh *me, const uint index, const bo
       if (!BLI_BITMAP_TEST(poly_tag, i)) {
         mark = false;
 
-        const MLoop *ml = &loops[mp->loopstart];
-        for (int b = 0; b < mp->totloop; b++, ml++) {
+        const MPoly &poly = polys[i];
+        const MLoop *ml = &loops[poly.loopstart];
+        for (int b = 0; b < poly.totloop; b++, ml++) {
           if ((edges[ml->e].flag & ME_SEAM) == 0) {
             if (BLI_BITMAP_TEST(edge_tag, ml->e)) {
               mark = true;
@@ -258,7 +275,7 @@ static void select_linked_tfaces_with_seams(Mesh *me, const uint index, const bo
 
         if (mark) {
           BLI_BITMAP_ENABLE(poly_tag, i);
-          BKE_mesh_poly_edgebitmap_insert(edge_tag, mp, &loops[mp->loopstart]);
+          BKE_mesh_poly_edgebitmap_insert(edge_tag, &poly, &loops[poly.loopstart]);
           do_it = true;
         }
       }
@@ -268,9 +285,8 @@ static void select_linked_tfaces_with_seams(Mesh *me, const uint index, const bo
   MEM_freeN(edge_tag);
 
   for (int i = 0; i < me->totpoly; i++) {
-    MPoly *mp = &polys[index];
     if (BLI_BITMAP_TEST(poly_tag, i)) {
-      SET_FLAG_FROM_TEST(mp->flag, select, ME_FACE_SEL);
+      select_poly.span[i] = select;
     }
   }
 
@@ -305,17 +321,17 @@ bool paintface_deselect_all_visible(bContext *C, Object *ob, int action, bool fl
     return false;
   }
 
-  MutableSpan<MPoly> polys = me->polys_for_write();
-  bke::AttributeAccessor attributes = me->attributes();
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
       ".hide_poly", ATTR_DOMAIN_FACE, false);
+  bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
 
   if (action == SEL_TOGGLE) {
     action = SEL_SELECT;
 
     for (int i = 0; i < me->totpoly; i++) {
-      MPoly *mpoly = &polys[i];
-      if (!hide_poly[i] && mpoly->flag & ME_FACE_SEL) {
+      if (!hide_poly[i] && select_poly.span[i]) {
         action = SEL_DESELECT;
         break;
       }
@@ -325,29 +341,29 @@ bool paintface_deselect_all_visible(bContext *C, Object *ob, int action, bool fl
   bool changed = false;
 
   for (int i = 0; i < me->totpoly; i++) {
-    MPoly *mpoly = &polys[i];
-    if (!hide_poly[i]) {
-      switch (action) {
-        case SEL_SELECT:
-          if ((mpoly->flag & ME_FACE_SEL) == 0) {
-            mpoly->flag |= ME_FACE_SEL;
-            changed = true;
-          }
-          break;
-        case SEL_DESELECT:
-          if ((mpoly->flag & ME_FACE_SEL) != 0) {
-            mpoly->flag &= ~ME_FACE_SEL;
-            changed = true;
-          }
-          break;
-        case SEL_INVERT:
-          mpoly->flag ^= ME_FACE_SEL;
-          changed = true;
-          break;
-      }
+    if (hide_poly[i]) {
+      continue;
+    }
+    const bool old_selection = select_poly.span[i];
+    switch (action) {
+      case SEL_SELECT:
+        select_poly.span[i] = true;
+        break;
+      case SEL_DESELECT:
+        select_poly.span[i] = false;
+        break;
+      case SEL_INVERT:
+        select_poly.span[i] = !select_poly.span[i];
+        changed = true;
+        break;
+    }
+    if (old_selection != select_poly.span[i]) {
+      changed = true;
     }
   }
 
+  select_poly.finish();
+
   if (changed) {
     if (flush_flags) {
       paintface_flush_flags(C, ob, true, false);
@@ -375,15 +391,17 @@ bool paintface_minmax(Object *ob, float r_min[3], float r_max[3])
   bke::AttributeAccessor attributes = me->attributes();
   const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
       ".hide_poly", ATTR_DOMAIN_FACE, false);
+  const VArray<bool> select_poly = attributes.lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
 
   for (int i = 0; i < me->totpoly; i++) {
-    const MPoly *mp = &polys[i];
-    if (hide_poly[i] || !(mp->flag & ME_FACE_SEL)) {
+    if (hide_poly[i] || !select_poly[i]) {
       continue;
     }
 
-    const MLoop *ml = &loops[mp->loopstart];
-    for (int b = 0; b < mp->totloop; b++, ml++) {
+    const MPoly &poly = polys[i];
+    const MLoop *ml = &loops[poly.loopstart];
+    for (int b = 0; b < poly.totloop; b++, ml++) {
       mul_v3_m3v3(vec, bmat, verts[ml->v].co);
       add_v3_v3v3(vec, vec, ob->obmat[3]);
       minmax_v3v3_v3(r_min, r_max, vec);
@@ -401,7 +419,6 @@ bool paintface_mouse_select(bContext *C,
                             Object *ob)
 {
   using namespace blender;
-  MPoly *mpoly_sel = nullptr;
   uint index;
   bool changed = false;
   bool found = false;
@@ -409,14 +426,14 @@ bool paintface_mouse_select(bContext *C,
   /* Get the face under the cursor */
   Mesh *me = BKE_mesh_from_object(ob);
 
-  MutableSpan<MPoly> polys = me->polys_for_write();
-  bke::AttributeAccessor attributes = me->attributes();
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
       ".hide_poly", ATTR_DOMAIN_FACE, false);
+  bke::AttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
 
   if (ED_mesh_pick_face(C, ob, mval, ED_MESH_PICK_DEFAULT_FACE_DIST, &index)) {
     if (index < me->totpoly) {
-      mpoly_sel = polys.data() + index;
       if (!hide_poly[index]) {
         found = true;
       }
@@ -424,7 +441,7 @@ bool paintface_mouse_select(bContext *C,
   }
 
   if (params->sel_op == SEL_OP_SET) {
-    if ((found && params->select_passthrough) && (mpoly_sel->flag & ME_FACE_SEL)) {
+    if ((found && params->select_passthrough) && select_poly.varray[index]) {
       found = false;
     }
     else if (found || params->deselect_all) {
@@ -437,31 +454,19 @@ bool paintface_mouse_select(bContext *C,
     me->act_face = (int)index;
 
     switch (params->sel_op) {
-      case SEL_OP_ADD: {
-        mpoly_sel->flag |= ME_FACE_SEL;
+      case SEL_OP_SET:
+      case SEL_OP_ADD:
+        select_poly.varray.set(index, true);
         break;
-      }
-      case SEL_OP_SUB: {
-        mpoly_sel->flag &= ~ME_FACE_SEL;
+      case SEL_OP_SUB:
+        select_poly.varray.set(index, false);
         break;
-      }
-      case SEL_OP_XOR: {
-        if (mpoly_sel->flag & ME_FACE_SEL) {
-          mpoly_sel->flag &= ~ME_FACE_SEL;
-        }
-        else {
-          mpoly_sel->flag |= ME_FACE_SEL;
-        }
-        break;
-      }
-      case SEL_OP_SET: {
-        mpoly_sel->flag |= ME_FACE_SEL;
+      case SEL_OP_XOR:
+        select_poly.varray.set(index, !select_poly.varray[index]);
         break;
-      }
-      case SEL_OP_AND: {
+      case SEL_OP_AND:
         BLI_assert_unreachable(); /* Doesn't make sense for picking. */
         break;
-      }
     }
 
     /* image window redraw */
@@ -476,10 +481,9 @@ bool paintface_mouse_select(bContext *C,
 void paintvert_flush_flags(Object *ob)
 {
   using namespace blender;
+  using namespace blender;
   Mesh *me = BKE_mesh_from_object(ob);
   Mesh *me_eval = BKE_object_get_evaluated_mesh(ob);
-  const int *index_array = nullptr;
-
   if (me == nullptr) {
     return;
   }
@@ -492,25 +496,42 @@ void paintvert_flush_flags(Object *ob)
     return;
   }
 
-  index_array = (const int *)CustomData_get_layer(&me_eval->vdata, CD_ORIGINDEX);
+  const bke::AttributeAccessor attributes_orig = me->attributes();
+  bke::MutableAttributeAccessor attributes_eval = me_eval->attributes_for_write();
 
-  const Span<MVert> verts = me->verts_for_write();
-  MutableSpan<MVert> verts_eval = me_eval->verts_for_write();
+  const int *orig_indices = (const int *)CustomData_get_layer(&me_eval->vdata, CD_ORIGINDEX);
 
-  if (index_array) {
-    int orig_index;
-    for (const int i : verts_eval.index_range()) {
-      orig_index = index_array[i];
-      if (orig_index != ORIGINDEX_NONE) {
-        verts_eval[i].flag = verts[index_array[i]].flag;
+  const VArray<bool> hide_vert_orig = attributes_orig.lookup_or_default<bool>(
+      ".hide_vert", ATTR_DOMAIN_POINT, false);
+  bke::SpanAttributeWriter<bool> hide_vert_eval =
+      attributes_eval.lookup_or_add_for_write_only_span<bool>(".hide_vert", ATTR_DOMAIN_POINT);
+  if (orig_indices) {
+    for (const int i : hide_vert_eval.span.index_range()) {
+      if (orig_indices[i] != ORIGINDEX_NONE) {
+        hide_vert_eval.span[i] = hide_vert_orig[orig_indices[i]];
       }
     }
   }
   else {
-    for (const int i : verts_eval.index_range()) {
-      verts_eval[i].flag = verts[i].flag;
+    hide_vert_orig.materialize(hide_vert_eval.span);
+  }
+  hide_vert_eval.finish();
+
+  const VArray<bool> select_vert_orig = attributes_orig.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  bke::SpanAttributeWriter<bool> select_vert_eval =
+      attributes_eval.lookup_or_add_for_write_only_span<bool>(".select_vert", ATTR_DOMAIN_POINT);
+  if (orig_indices) {
+    for (const int i : select_vert_eval.span.index_range()) {
+      if (orig_indices[i] != ORIGINDEX_NONE) {
+        select_vert_eval.span[i] = select_vert_orig[orig_indices[i]];
+      }
     }
   }
+  else {
+    select_vert_orig.materialize(select_vert_eval.span);
+  }
+  select_vert_eval.finish();
 
   BKE_mesh_batch_cache_dirty_tag(me, BKE_MESH_BATCH_DIRTY_ALL);
 }
@@ -529,17 +550,17 @@ bool paintvert_deselect_all_visible(Object *ob, int action, bool flush_flags)
     return false;
   }
 
-  MutableSpan<MVert> verts = me->verts_for_write();
-  bke::AttributeAccessor attributes = me->attributes();
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_vert = attributes.lookup_or_default<bool>(
       ".hide_vert", ATTR_DOMAIN_POINT, false);
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
 
   if (action == SEL_TOGGLE) {
     action = SEL_SELECT;
 
     for (int i = 0; i < me->totvert; i++) {
-      MVert *mvert = &verts[i];
-      if (!hide_vert[i] && mvert->flag & SELECT) {
+      if (!hide_vert[i] && select_vert.span[i]) {
         action = SEL_DESELECT;
         break;
       }
@@ -548,29 +569,28 @@ bool paintvert_deselect_all_visible(Object *ob, int action, bool flush_flags)
 
   bool changed = false;
   for (int i = 0; i < me->totvert; i++) {
-    MVert *mvert = &verts[i];
-    if (!hide_vert[i]) {
-      switch (action) {
-        case SEL_SELECT:
-          if ((mvert->flag & SELECT) == 0) {
-            mvert->flag |= SELECT;
-            changed = true;
-          }
-          break;
-        case SEL_DESELECT:
-          if ((mvert->flag & SELECT) != 0) {
-            mvert->flag &= ~SELECT;
-            changed = true;
-          }
-          break;
-        case SEL_INVERT:
-          mvert->flag ^= SELECT;
-          changed = true;
-          break;
-      }
+    if (hide_vert[i]) {
+      continue;
+    }
+    const bool old_selection = select_vert.span[i];
+    switch (action) {
+      case SEL_SELECT:
+        select_vert.span[i] = true;
+        break;
+      case SEL_DESELECT:
+        select_vert.span[i] = false;
+        break;
+      case SEL_INVERT:
+        select_vert.span[i] = !select_vert.span[i];
+        break;
+    }
+    if (old_selection != select_vert.span[i]) {
+      changed = true;
     }
   }
 
+  select_vert.finish();
+
   if (changed) {
     /* handle mselect */
     if (action == SEL_SELECT) {
@@ -606,22 +626,23 @@ void paintvert_select_ungrouped(Object *ob, bool extend, bool flush_flags)
     paintvert_deselect_all_visible(ob, SEL_DESELECT, false);
   }
 
-  MutableSpan<MVert> verts = me->verts_for_write();
-  bke::AttributeAccessor attributes = me->attributes();
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_vert = attributes.lookup_or_default<bool>(
       ".hide_vert", ATTR_DOMAIN_POINT, false);
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
 
-  for (int i = 0; i < me->totvert; i++) {
-    MVert *mv = &verts[i];
-    const MDeformVert *dv = &dverts[i];
+  for (const int i : select_vert.span.index_range()) {
     if (!hide_vert[i]) {
-      if (dv->dw == nullptr) {
+      if (dverts[i].dw == nullptr) {
         /* if null weight then not grouped */
-        mv->flag |= SELECT;
+        select_vert.span[i] = true;
       }
     }
   }
 
+  select_vert.finish();
+
   if (flush_flags) {
     paintvert_flush_flags(ob);
   }
@@ -635,24 +656,25 @@ void paintvert_hide(bContext *C, Object *ob, const bool unselected)
     return;
   }
 
-  MutableSpan<MVert> verts = me->verts_for_write();
   bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   bke::SpanAttributeWriter<bool> hide_vert = attributes.lookup_or_add_for_write_span<bool>(
       ".hide_vert", ATTR_DOMAIN_POINT);
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
 
-  for (const int i : verts.index_range()) {
-    MVert &vert = verts[i];
+  for (const int i : hide_vert.span.index_range()) {
     if (!hide_vert.span[i]) {
-      if (((vert.flag & SELECT) == 0) == unselected) {
+      if (!select_vert.span[i] == unselected) {
         hide_vert.span[i] = true;
       }
     }
 
     if (hide_vert.span[i]) {
-      vert.flag &= ~SELECT;
+      select_vert.span[i] = false;
     }
   }
   hide_vert.finish();
+  select_vert.finish();
 
   BKE_mesh_flush_hidden_from_verts(me);
 
@@ -668,18 +690,20 @@ void paintvert_reveal(bContext *C, Object *ob, const bool select)
     return;
   }
 
-  MutableSpan<MVert> verts = me->verts_for_write();
   bke::MutableAttributeAccessor attributes = me->attributes_for_write();
   const VArray<bool> hide_vert = attributes.lookup_or_default<bool>(
       ".hide_vert", ATTR_DOMAIN_POINT, false);
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
 
-  for (const int i : verts.index_range()) {
-    MVert &vert = verts[i];
+  for (const int i : select_vert.span.index_range()) {
     if (hide_vert[i]) {
-      SET_FLAG_FROM_TEST(vert.flag, select, SELECT);
+      select_vert.span[i] = select;
     }
   }
 
+  select_vert.finish();
+
   /* Remove the hide attribute to reveal all vertices. */
   attributes.remove(".hide_vert");
 
diff --git a/source/blender/editors/mesh/mesh_data.cc b/source/blender/editors/mesh/mesh_data.cc
index 710cc6c88d9..dc3389844b8 100644
--- a/source/blender/editors/mesh/mesh_data.cc
+++ b/source/blender/editors/mesh/mesh_data.cc
@@ -1134,6 +1134,7 @@ void ED_mesh_update(Mesh *mesh, bContext *C, bool calc_edges, bool calc_edges_lo
 
 static void mesh_add_verts(Mesh *mesh, int len)
 {
+  using namespace blender;
   if (len == 0) {
     return;
   }
@@ -1152,17 +1153,18 @@ static void mesh_add_verts(Mesh *mesh, int len)
 
   BKE_mesh_runtime_clear_cache(mesh);
 
-  const int old_vertex_num = mesh->totvert;
   mesh->totvert = totvert;
 
-  MutableSpan<MVert> verts = mesh->verts_for_write();
-  for (MVert &vert : verts.drop_front(old_vertex_num)) {
-    vert.flag = SELECT;
-  }
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
+  select_vert.span.take_back(len).fill(true);
+  select_vert.finish();
 }
 
 static void mesh_add_edges(Mesh *mesh, int len)
 {
+  using namespace blender;
   CustomData edata;
   int totedge;
 
@@ -1185,13 +1187,18 @@ static void mesh_add_edges(Mesh *mesh, int len)
 
   BKE_mesh_runtime_clear_cache(mesh);
 
-  const int old_edges_num = mesh->totedge;
   mesh->totedge = totedge;
 
   MutableSpan<MEdge> edges = mesh->edges_for_write();
-  for (MEdge &edge : edges.drop_front(old_edges_num)) {
-    edge.flag = ME_EDGEDRAW | ME_EDGERENDER | SELECT;
+  for (MEdge &edge : edges.take_back(len)) {
+    edge.flag = ME_EDGEDRAW | ME_EDGERENDER;
   }
+
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_edge = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_edge", ATTR_DOMAIN_EDGE);
+  select_edge.span.take_back(len).fill(true);
+  select_edge.finish();
 }
 
 static void mesh_add_loops(Mesh *mesh, int len)
@@ -1223,6 +1230,7 @@ static void mesh_add_loops(Mesh *mesh, int len)
 
 static void mesh_add_polys(Mesh *mesh, int len)
 {
+  using namespace blender;
   CustomData pdata;
   int totpoly;
 
@@ -1245,13 +1253,13 @@ static void mesh_add_polys(Mesh *mesh, int len)
 
   BKE_mesh_runtime_clear_cache(mesh);
 
-  const int old_polys_num = mesh->totpoly;
   mesh->totpoly = totpoly;
 
-  MutableSpan<MPoly> polys = mesh->polys_for_write();
-  for (MPoly &poly : polys.drop_front(old_polys_num)) {
-    poly.flag = ME_FACE_SEL;
-  }
+  bke::MutableAttributeAccessor attributes = mesh->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
+  select_poly.span.take_back(len).fill(true);
+  select_poly.finish();
 }
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/editors/object/object_modifier.cc b/source/blender/editors/object/object_modifier.cc
index f82c0938b51..3d995c84639 100644
--- a/source/blender/editors/object/object_modifier.cc
+++ b/source/blender/editors/object/object_modifier.cc
@@ -530,6 +530,7 @@ bool ED_object_modifier_convert_psys_to_mesh(ReportList *UNUSED(reports),
                                              Object *ob,
                                              ModifierData *md)
 {
+  using namespace blender;
   int cvert = 0;
 
   if (md->type != eModifierType_ParticleSystem) {
@@ -599,13 +600,18 @@ bool ED_object_modifier_convert_psys_to_mesh(ReportList *UNUSED(reports),
   MVert *mvert = verts.data();
   MEdge *medge = edges.data();
 
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
+
   /* copy coordinates */
+  int vert_index = 0;
   cache = psys_eval->pathcache;
   for (int a = 0; a < part_num; a++) {
     ParticleCacheKey *key = cache[a];
     int kmax = key->segments;
-    for (int k = 0; k <= kmax; k++, key++, cvert++, mvert++) {
-      copy_v3_v3(mvert->co, key->co);
+    for (int k = 0; k <= kmax; k++, key++, cvert++, vert_index++) {
+      copy_v3_v3(mvert[vert_index].co, key->co);
       if (k) {
         medge->v1 = cvert - 1;
         medge->v2 = cvert;
@@ -614,7 +620,7 @@ bool ED_object_modifier_convert_psys_to_mesh(ReportList *UNUSED(reports),
       }
       else {
         /* cheap trick to select the roots */
-        mvert->flag |= SELECT;
+        select_vert.span[vert_index] = true;
       }
     }
   }
@@ -623,8 +629,8 @@ bool ED_object_modifier_convert_psys_to_mesh(ReportList *UNUSED(reports),
   for (int a = 0; a < child_num; a++) {
     ParticleCacheKey *key = cache[a];
     int kmax = key->segments;
-    for (int k = 0; k <= kmax; k++, key++, cvert++, mvert++) {
-      copy_v3_v3(mvert->co, key->co);
+    for (int k = 0; k <= kmax; k++, key++, cvert++, vert_index++) {
+      copy_v3_v3(mvert[vert_index].co, key->co);
       if (k) {
         medge->v1 = cvert - 1;
         medge->v2 = cvert;
@@ -633,11 +639,13 @@ bool ED_object_modifier_convert_psys_to_mesh(ReportList *UNUSED(reports),
       }
       else {
         /* cheap trick to select the roots */
-        mvert->flag |= SELECT;
+        select_vert.span[vert_index] = true;
       }
     }
   }
 
+  select_vert.finish();
+
   DEG_relations_tag_update(bmain);
 
   return true;
diff --git a/source/blender/editors/object/object_vgroup.cc b/source/blender/editors/object/object_vgroup.cc
index 1d1263494c7..44fea0b32f0 100644
--- a/source/blender/editors/object/object_vgroup.cc
+++ b/source/blender/editors/object/object_vgroup.cc
@@ -31,6 +31,7 @@
 #include "BLI_utildefines_stack.h"
 #include "BLI_vector.hh"
 
+#include "BKE_attribute.hh"
 #include "BKE_context.h"
 #include "BKE_customdata.h"
 #include "BKE_deform.h"
@@ -154,6 +155,7 @@ bool ED_vgroup_parray_alloc(ID *id,
                             int *dvert_tot,
                             const bool use_vert_sel)
 {
+  using namespace blender;
   *dvert_tot = 0;
   *dvert_arr = nullptr;
 
@@ -200,7 +202,6 @@ bool ED_vgroup_parray_alloc(ID *id,
           return true;
         }
         if (!me->deform_verts().is_empty()) {
-          const Span<MVert> verts = me->verts();
           MutableSpan<MDeformVert> dverts = me->deform_verts_for_write();
 
           *dvert_tot = me->totvert;
@@ -208,8 +209,12 @@ bool ED_vgroup_parray_alloc(ID *id,
               MEM_mallocN(sizeof(void *) * me->totvert, __func__));
 
           if (use_vert_sel) {
+            const bke::AttributeAccessor attributes = me->attributes();
+            const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+                ".select_vert", ATTR_DOMAIN_POINT, false);
+
             for (int i = 0; i < me->totvert; i++) {
-              (*dvert_arr)[i] = (verts[i].flag & SELECT) ? &dverts[i] : nullptr;
+              (*dvert_arr)[i] = select_vert[i] ? &dverts[i] : nullptr;
             }
           }
           else {
@@ -636,6 +641,7 @@ static bool vgroup_normalize_active_vertex(Object *ob, eVGroupSelect subset_type
 
 static void vgroup_copy_active_to_sel(Object *ob, eVGroupSelect subset_type)
 {
+  using namespace blender;
   Mesh *me = static_cast<Mesh *>(ob->data);
   BMEditMesh *em = me->edit_mesh;
   MDeformVert *dvert_act;
@@ -663,14 +669,17 @@ static void vgroup_copy_active_to_sel(Object *ob, eVGroupSelect subset_type)
     }
   }
   else {
-    const Span<MVert> verts = me->verts();
+    const bke::AttributeAccessor attributes = me->attributes();
+    const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT, false);
+
     int v_act;
 
     dvert_act = ED_mesh_active_dvert_get_ob(ob, &v_act);
     if (dvert_act) {
       MutableSpan<MDeformVert> dverts = me->deform_verts_for_write();
       for (i = 0; i < me->totvert; i++) {
-        if ((verts[i].flag & SELECT) && &dverts[i] != dvert_act) {
+        if (select_vert[i] && &dverts[i] != dvert_act) {
           BKE_defvert_copy_subset(&dverts[i], dvert_act, vgroup_validmap, vgroup_tot);
           if (me->symmetry & ME_SYMMETRY_X) {
             ED_mesh_defvert_mirror_update_ob(ob, -1, i);
@@ -1011,6 +1020,7 @@ void ED_vgroup_select_by_name(Object *ob, const char *name)
 /* only in editmode */
 static void vgroup_select_verts(Object *ob, int select)
 {
+  using namespace blender;
   const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
   const ListBase *defbase = BKE_object_defgroup_list(ob);
@@ -1051,26 +1061,21 @@ static void vgroup_select_verts(Object *ob, int select)
     else {
       const Span<MDeformVert> dverts = me->deform_verts();
       if (!dverts.is_empty()) {
-        const bool *hide_vert = (const bool *)CustomData_get_layer_named(
-            &me->vdata, CD_PROP_BOOL, ".hide_vert");
-        MVert *mv;
-        int i;
-
-        mv = me->verts_for_write().data();
-
-        for (i = 0; i < me->totvert; i++, mv++) {
-          if (!(hide_vert != nullptr && hide_vert[i])) {
+        bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+        const VArray<bool> hide_vert = attributes.lookup_or_default<bool>(
+            ".hide_vert", ATTR_DOMAIN_POINT, false);
+        bke::SpanAttributeWriter<bool> select_vert =
+            attributes.lookup_or_add_for_write_only_span<bool>(".select_vert", ATTR_DOMAIN_POINT);
+
+        for (const int i : select_vert.span.index_range()) {
+          if (!hide_vert[i]) {
             if (BKE_defvert_find_index(&dverts[i], def_nr)) {
-              if (select) {
-                mv->flag |= SELECT;
-              }
-              else {
-                mv->flag &= ~SELECT;
-              }
+              select_vert.span[i] = select;
             }
           }
         }
 
+        select_vert.finish();
         paintvert_flush_flags(ob);
       }
     }
@@ -1519,6 +1524,7 @@ static void moveCloserToDistanceFromPlane(Depsgraph *depsgraph,
 static void vgroup_fix(
     const bContext *C, Scene *UNUSED(scene), Object *ob, float distToBe, float strength, float cp)
 {
+  using namespace blender;
   Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
   Scene *scene_eval = DEG_get_evaluated_scene(depsgraph);
   Object *object_eval = DEG_get_evaluated_object(depsgraph, ob);
@@ -1529,8 +1535,11 @@ static void vgroup_fix(
   if (!(me->editflag & ME_EDIT_PAINT_VERT_SEL)) {
     return;
   }
+  const bke::AttributeAccessor attributes = me->attributes();
+  const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
   for (i = 0; i < me->totvert && mvert; i++, mvert++) {
-    if (mvert->flag & SELECT) {
+    if (select_vert[i]) {
       blender::Vector<int> verts = getSurroundingVerts(me, i);
       const int count = verts.size();
       if (!verts.is_empty()) {
@@ -1893,6 +1902,7 @@ static void vgroup_smooth_subset(Object *ob,
                                  const int repeat,
                                  const float fac_expand)
 {
+  using namespace blender;
   const float ifac = 1.0f - fac;
   MDeformVert **dvert_array = nullptr;
   int dvert_tot = 0;
@@ -1912,6 +1922,10 @@ static void vgroup_smooth_subset(Object *ob,
   BMesh *bm = em ? em->bm : nullptr;
   Mesh *me = em ? nullptr : static_cast<Mesh *>(ob->data);
 
+  const bke::AttributeAccessor attributes = me->attributes();
+  const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   MeshElemMap *emap;
   int *emap_mem;
 
@@ -1955,7 +1969,7 @@ static void vgroup_smooth_subset(Object *ob,
                                nullptr;
 
 #define IS_ME_VERT_READ(v) (use_hide ? !(hide_vert && hide_vert[v]) : true)
-#define IS_ME_VERT_WRITE(v) (use_select ? (((v)->flag & SELECT) != 0) : true)
+#define IS_ME_VERT_WRITE(v) (use_select ? select_vert[v] : true)
 
   /* initialize used verts */
   if (bm) {
@@ -1975,11 +1989,9 @@ static void vgroup_smooth_subset(Object *ob,
     }
   }
   else {
-    const Span<MVert> verts = me->verts();
     const blender::Span<MEdge> edges = me->edges();
     for (int i = 0; i < dvert_tot; i++) {
-      const MVert *v = &verts[i];
-      if (IS_ME_VERT_WRITE(v)) {
+      if (IS_ME_VERT_WRITE(i)) {
         for (int j = 0; j < emap[i].count; j++) {
           const MEdge *e = &edges[emap[i].indices[j]];
           const int i_other = (e->v1 == i) ? e->v2 : e->v1;
@@ -2053,7 +2065,7 @@ static void vgroup_smooth_subset(Object *ob,
           const blender::Span<MEdge> edges = me->edges();
 
           /* checked already */
-          BLI_assert(IS_ME_VERT_WRITE(&me->verts()[i]));
+          BLI_assert(IS_ME_VERT_WRITE(i));
 
           for (j = 0; j < emap[i].count; j++) {
             const MEdge *e = &edges[emap[i].indices[j]];
@@ -2360,6 +2372,7 @@ void ED_vgroup_mirror(Object *ob,
                       int *r_totmirr,
                       int *r_totfail)
 {
+  using namespace blender;
   /* TODO: vgroup locking.
    * TODO: face masking. */
 
@@ -2458,7 +2471,6 @@ void ED_vgroup_mirror(Object *ob,
     }
     else {
       /* object mode / weight paint */
-      const MVert *mv, *mv_mirr;
       int vidx, vidx_mirr;
       const bool use_vert_sel = (me->editflag & ME_EDIT_PAINT_VERT_SEL) != 0;
 
@@ -2471,19 +2483,20 @@ void ED_vgroup_mirror(Object *ob,
       }
 
       BLI_bitmap *vert_tag = BLI_BITMAP_NEW(me->totvert, __func__);
-      const MVert *verts = me->verts().data();
       MutableSpan<MDeformVert> dverts = me->deform_verts_for_write();
+      const bke::AttributeAccessor attributes = me->attributes();
+      const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+          ".select_vert", ATTR_DOMAIN_POINT, false);
 
-      for (vidx = 0, mv = verts; vidx < me->totvert; vidx++, mv++) {
+      for (vidx = 0; vidx < me->totvert; vidx++) {
         if (!BLI_BITMAP_TEST(vert_tag, vidx)) {
           if ((vidx_mirr = mesh_get_x_mirror_vert(ob, nullptr, vidx, use_topology)) != -1) {
             if (vidx != vidx_mirr) {
-              mv_mirr = &verts[vidx_mirr];
               if (!BLI_BITMAP_TEST(vert_tag, vidx_mirr)) {
 
                 if (use_vert_sel) {
-                  sel = mv->flag & SELECT;
-                  sel_mirr = mv_mirr->flag & SELECT;
+                  sel = select_vert[vidx];
+                  sel_mirr = select_vert[vidx_mirr];
                 }
 
                 if (sel || sel_mirr) {
@@ -2587,6 +2600,7 @@ static void vgroup_delete_active(Object *ob)
 /* only in editmode */
 static void vgroup_assign_verts(Object *ob, const float weight)
 {
+  using namespace blender;
   const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
   const ListBase *defbase = BKE_object_defgroup_list(ob);
@@ -2625,15 +2639,16 @@ static void vgroup_assign_verts(Object *ob, const float weight)
       }
     }
     else {
-      const Span<MVert> verts = me->verts();
+      const bke::AttributeAccessor attributes = me->attributes();
+      const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+          ".select_vert", ATTR_DOMAIN_POINT, false);
+
       MutableSpan<MDeformVert> dverts = me->deform_verts_for_write();
-      MDeformVert *dv = dverts.data();
 
-      for (int i = 0; i < me->totvert; i++, dv++) {
-        const MVert *mv = &verts[i];
-        if (mv->flag & SELECT) {
+      for (int i = 0; i < me->totvert; i++) {
+        if (select_vert[i]) {
           MDeformWeight *dw;
-          dw = BKE_defvert_ensure_index(dv, def_nr);
+          dw = BKE_defvert_ensure_index(&dverts[i], def_nr);
           if (dw) {
             dw->weight = weight;
           }
@@ -4314,6 +4329,7 @@ void OBJECT_OT_vertex_group_move(wmOperatorType *ot)
 
 static void vgroup_copy_active_to_sel_single(Object *ob, const int def_nr)
 {
+  using namespace blender;
   MDeformVert *dvert_act;
 
   Mesh *me = static_cast<Mesh *>(ob->data);
@@ -4348,7 +4364,6 @@ static void vgroup_copy_active_to_sel_single(Object *ob, const int def_nr)
     }
   }
   else {
-    MDeformVert *dv;
     int v_act;
 
     dvert_act = ED_mesh_active_dvert_get_ob(ob, &v_act);
@@ -4356,14 +4371,14 @@ static void vgroup_copy_active_to_sel_single(Object *ob, const int def_nr)
       return;
     }
 
-    const Span<MVert> verts = me->verts();
     MutableSpan<MDeformVert> dverts = me->deform_verts_for_write();
+    const bke::AttributeAccessor attributes = me->attributes();
+    const VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT, false);
 
-    dv = dverts.data();
-    for (i = 0; i < me->totvert; i++, dv++) {
-      if ((verts[i].flag & SELECT) && (dv != dvert_act)) {
-
-        BKE_defvert_copy_index(dv, def_nr, dvert_act, def_nr);
+    for (i = 0; i < me->totvert; i++) {
+      if (select_vert[i] && (&dverts[i] != dvert_act)) {
+        BKE_defvert_copy_index(&dverts[i], def_nr, dvert_act, def_nr);
 
         if (me->symmetry & ME_SYMMETRY_X) {
           ED_mesh_defvert_mirror_update_ob(ob, -1, i);
diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index 946a59d0001..bae5050f0ac 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -415,6 +415,7 @@ typedef struct ProjPaintState {
   const float (*vert_normals)[3];
   const MEdge *medge_eval;
   const MPoly *mpoly_eval;
+  const bool *select_poly_eval;
   const int *material_indices;
   const MLoop *mloop_eval;
   const MLoopTri *mlooptri_eval;
@@ -4062,6 +4063,8 @@ static bool proj_paint_state_mesh_eval_init(const bContext *C, ProjPaintState *p
   }
   ps->mloop_eval = BKE_mesh_loops(ps->me_eval);
   ps->mpoly_eval = BKE_mesh_polys(ps->me_eval);
+  ps->select_poly_eval = (const bool *)CustomData_get_layer_named(
+      &ps->me_eval->pdata, CD_PROP_BOOL, ".select_poly");
   ps->material_indices = (const int *)CustomData_get_layer_named(
       &ps->me_eval->pdata, CD_PROP_INT32, "material_index");
 
@@ -4145,7 +4148,7 @@ static bool project_paint_clone_face_skip(ProjPaintState *ps,
 }
 
 typedef struct {
-  const MPoly *mpoly_orig;
+  const bool *select_poly_orig;
 
   const int *index_mp_to_orig;
 } ProjPaintFaceLookup;
@@ -4154,8 +4157,10 @@ static void proj_paint_face_lookup_init(const ProjPaintState *ps, ProjPaintFaceL
 {
   memset(face_lookup, 0, sizeof(*face_lookup));
   if (ps->do_face_sel) {
+    Mesh *orig_mesh = (Mesh *)ps->ob->data;
     face_lookup->index_mp_to_orig = CustomData_get_layer(&ps->me_eval->pdata, CD_ORIGINDEX);
-    face_lookup->mpoly_orig = BKE_mesh_polys((Mesh *)ps->ob->data);
+    face_lookup->select_poly_orig = CustomData_get_layer_named(
+        &orig_mesh->pdata, CD_PROP_BOOL, ".select_poly");
   }
 }
 
@@ -4166,17 +4171,12 @@ static bool project_paint_check_face_sel(const ProjPaintState *ps,
 {
   if (ps->do_face_sel) {
     int orig_index;
-    const MPoly *mp;
 
     if ((face_lookup->index_mp_to_orig != NULL) &&
         (((orig_index = (face_lookup->index_mp_to_orig[lt->poly]))) != ORIGINDEX_NONE)) {
-      mp = &face_lookup->mpoly_orig[orig_index];
+      return face_lookup->select_poly_orig && face_lookup->select_poly_orig[orig_index];
     }
-    else {
-      mp = &ps->mpoly_eval[lt->poly];
-    }
-
-    return ((mp->flag & ME_FACE_SEL) != 0);
+    return ps->select_poly_eval && ps->select_poly_eval[lt->poly];
   }
   return true;
 }
diff --git a/source/blender/editors/sculpt_paint/paint_vertex.cc b/source/blender/editors/sculpt_paint/paint_vertex.cc
index c38a79cb6bb..9abc3c5112e 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.cc
+++ b/source/blender/editors/sculpt_paint/paint_vertex.cc
@@ -32,6 +32,7 @@
 #include "RNA_prototypes.h"
 
 #include "BKE_attribute.h"
+#include "BKE_attribute.hh"
 #include "BKE_brush.h"
 #include "BKE_colortools.h"
 #include "BKE_context.h"
@@ -1958,6 +1959,10 @@ static void do_wpaint_brush_blur_task_cb_ex(void *__restrict userdata,
   const float *sculpt_normal_frontface = SCULPT_brush_frontface_normal_from_falloff_shape(
       ss, data->brush->falloff_shape);
 
+  const blender::bke::AttributeAccessor attributes = data->me->attributes();
+  const blender::VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   /* For each vertex */
   PBVHVertexIter vd;
   BKE_pbvh_vertex_iter_begin (ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE) {
@@ -1967,9 +1972,8 @@ static void do_wpaint_brush_blur_task_cb_ex(void *__restrict userdata,
        * Otherwise, take the current vert. */
       const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v : vd.vert_indices[vd.i];
       const float grid_alpha = has_grids ? 1.0f / vd.gridsize : 1.0f;
-      const char v_flag = ss->mvert[v_index].flag;
       /* If the vertex is selected */
-      if (!(use_face_sel || use_vert_sel) || v_flag & SELECT) {
+      if (!(use_face_sel || use_vert_sel) || select_vert[v_index]) {
         /* Get the average poly weight */
         int total_hit_loops = 0;
         float weight_final = 0.0f;
@@ -2045,6 +2049,10 @@ static void do_wpaint_brush_smear_task_cb_ex(void *__restrict userdata,
   sub_v3_v3v3(brush_dir, cache->location, cache->last_location);
   project_plane_v3_v3v3(brush_dir, brush_dir, cache->view_normal);
 
+  const blender::bke::AttributeAccessor attributes = data->me->attributes();
+  const blender::VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   if (cache->is_last_valid && (normalize_v3(brush_dir) != 0.0f)) {
 
     SculptBrushTest test;
@@ -2065,7 +2073,7 @@ static void do_wpaint_brush_smear_task_cb_ex(void *__restrict userdata,
         const MVert *mv_curr = &ss->mvert[v_index];
 
         /* If the vertex is selected */
-        if (!(use_face_sel || use_vert_sel) || mv_curr->flag & SELECT) {
+        if (!(use_face_sel || use_vert_sel) || select_vert[v_index]) {
           float brush_strength = cache->bstrength;
           const float angle_cos = (use_normal && vd.no) ?
                                       dot_v3v3(sculpt_normal_frontface, vd.no) :
@@ -2158,6 +2166,10 @@ static void do_wpaint_brush_draw_task_cb_ex(void *__restrict userdata,
   const float *sculpt_normal_frontface = SCULPT_brush_frontface_normal_from_falloff_shape(
       ss, data->brush->falloff_shape);
 
+  const blender::bke::AttributeAccessor attributes = data->me->attributes();
+  const blender::VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   /* For each vertex */
   PBVHVertexIter vd;
   BKE_pbvh_vertex_iter_begin (ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE) {
@@ -2169,9 +2181,8 @@ static void do_wpaint_brush_draw_task_cb_ex(void *__restrict userdata,
       const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v : vd.vert_indices[vd.i];
       const float grid_alpha = has_grids ? 1.0f / vd.gridsize : 1.0f;
 
-      const char v_flag = ss->mvert[v_index].flag;
       /* If the vertex is selected */
-      if (!(use_face_sel || use_vert_sel) || v_flag & SELECT) {
+      if (!(use_face_sel || use_vert_sel) || select_vert[v_index]) {
         float brush_strength = cache->bstrength;
         const float angle_cos = (use_normal && vd.no) ? dot_v3v3(sculpt_normal_frontface, vd.no) :
                                                         1.0f;
@@ -2224,6 +2235,10 @@ static void do_wpaint_brush_calc_average_weight_cb_ex(
   const float *sculpt_normal_frontface = SCULPT_brush_frontface_normal_from_falloff_shape(
       ss, data->brush->falloff_shape);
 
+  const blender::bke::AttributeAccessor attributes = data->me->attributes();
+  const blender::VArray<bool> select_vert = attributes.lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   /* For each vertex */
   PBVHVertexIter vd;
   BKE_pbvh_vertex_iter_begin (ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE) {
@@ -2234,10 +2249,9 @@ static void do_wpaint_brush_calc_average_weight_cb_ex(
       if (angle_cos > 0.0 &&
           BKE_brush_curve_strength(data->brush, sqrtf(test.dist), cache->radius) > 0.0) {
         const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v : vd.vert_indices[vd.i];
-        const char v_flag = ss->mvert[v_index].flag;
 
         /* If the vertex is selected. */
-        if (!(use_face_sel || use_vert_sel) || v_flag & SELECT) {
+        if (!(use_face_sel || use_vert_sel) || select_vert[v_index]) {
           const MDeformVert *dv = &data->wpi->dvert[v_index];
           accum->len += 1;
           accum->value += wpaint_get_active_weight(dv, data->wpi);
@@ -2956,6 +2970,11 @@ static void do_vpaint_brush_blur_loops(bContext *C,
 
   Color *previous_color = static_cast<Color *>(ss->cache->prev_colors_vpaint);
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  const blender::VArray<bool> select_poly = me->attributes().lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
+
   blender::threading::parallel_for(IndexRange(totnode), 1LL, [&](IndexRange range) {
     for (int n : range) {
       const PBVHType pbvh_type = BKE_pbvh_type(ss->pbvh);
@@ -2987,10 +3006,9 @@ static void do_vpaint_brush_blur_loops(bContext *C,
           const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v :
                                           vd.vert_indices[vd.i];
           const float grid_alpha = has_grids ? 1.0f / vd.gridsize : 1.0f;
-          const MVert *mv = &ss->mvert[v_index];
 
           /* If the vertex is selected for painting. */
-          if (!use_vert_sel || mv->flag & SELECT) {
+          if (!use_vert_sel || select_vert[v_index]) {
             float brush_strength = cache->bstrength;
             const float angle_cos = (use_normal && vd.no) ?
                                         dot_v3v3(sculpt_normal_frontface, vd.no) :
@@ -3011,7 +3029,7 @@ static void do_vpaint_brush_blur_loops(bContext *C,
               for (int j = 0; j < gmap->vert_to_poly[v_index].count; j++) {
                 int p_index = gmap->vert_to_poly[v_index].indices[j];
                 const MPoly *mp = &ss->mpoly[p_index];
-                if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                if (!use_face_sel || select_poly[p_index]) {
                   total_hit_loops += mp->totloop;
                   for (int k = 0; k < mp->totloop; k++) {
                     const uint l_index = mp->loopstart + k;
@@ -3045,8 +3063,7 @@ static void do_vpaint_brush_blur_loops(bContext *C,
                   const int p_index = gmap->vert_to_poly[v_index].indices[j];
                   const int l_index = gmap->vert_to_loop[v_index].indices[j];
                   BLI_assert(ss->mloop[l_index].v == v_index);
-                  const MPoly *mp = &ss->mpoly[p_index];
-                  if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                  if (!use_face_sel || select_poly[p_index]) {
                     Color color_orig(0, 0, 0, 0); /* unused when array is nullptr */
 
                     if (previous_color != nullptr) {
@@ -3098,6 +3115,11 @@ static void do_vpaint_brush_blur_verts(bContext *C,
 
   Color *previous_color = static_cast<Color *>(ss->cache->prev_colors_vpaint);
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  const blender::VArray<bool> select_poly = me->attributes().lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
+
   blender::threading::parallel_for(IndexRange(totnode), 1LL, [&](IndexRange range) {
     for (int n : range) {
       const PBVHType pbvh_type = BKE_pbvh_type(ss->pbvh);
@@ -3129,10 +3151,9 @@ static void do_vpaint_brush_blur_verts(bContext *C,
           const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v :
                                           vd.vert_indices[vd.i];
           const float grid_alpha = has_grids ? 1.0f / vd.gridsize : 1.0f;
-          const MVert *mv = &ss->mvert[v_index];
 
           /* If the vertex is selected for painting. */
-          if (!use_vert_sel || mv->flag & SELECT) {
+          if (!use_vert_sel || select_vert[v_index]) {
             float brush_strength = cache->bstrength;
             const float angle_cos = (use_normal && vd.no) ?
                                         dot_v3v3(sculpt_normal_frontface, vd.no) :
@@ -3153,7 +3174,7 @@ static void do_vpaint_brush_blur_verts(bContext *C,
               for (int j = 0; j < gmap->vert_to_poly[v_index].count; j++) {
                 int p_index = gmap->vert_to_poly[v_index].indices[j];
                 const MPoly *mp = &ss->mpoly[p_index];
-                if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                if (!use_face_sel || select_poly[p_index]) {
                   total_hit_loops += mp->totloop;
                   for (int k = 0; k < mp->totloop; k++) {
                     const uint l_index = mp->loopstart + k;
@@ -3190,8 +3211,7 @@ static void do_vpaint_brush_blur_verts(bContext *C,
 
                   BLI_assert(ss->mloop[gmap->vert_to_loop[v_index].indices[j]].v == v_index);
 
-                  const MPoly *mp = &ss->mpoly[p_index];
-                  if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                  if (!use_face_sel || select_poly[p_index]) {
                     Color color_orig(0, 0, 0, 0); /* unused when array is nullptr */
 
                     if (previous_color != nullptr) {
@@ -3247,6 +3267,11 @@ static void do_vpaint_brush_smear(bContext *C,
   Color *color_prev_smear = static_cast<Color *>(vpd->smear.color_prev);
   Color *color_prev = reinterpret_cast<Color *>(ss->cache->prev_colors_vpaint);
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  const blender::VArray<bool> select_poly = me->attributes().lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
+
   blender::threading::parallel_for(IndexRange(totnode), 1LL, [&](IndexRange range) {
     for (int n : range) {
       float brush_size_pressure, brush_alpha_value, brush_alpha_pressure;
@@ -3283,7 +3308,7 @@ static void do_vpaint_brush_smear(bContext *C,
             const MVert *mv_curr = &ss->mvert[v_index];
 
             /* if the vertex is selected for painting. */
-            if (!use_vert_sel || mv_curr->flag & SELECT) {
+            if (!use_vert_sel || select_vert[v_index]) {
               /* Calc the dot prod. between ray norm on surf and current vert
                * (ie splash prevention factor), and only paint front facing verts. */
               float brush_strength = cache->bstrength;
@@ -3312,7 +3337,7 @@ static void do_vpaint_brush_smear(bContext *C,
                   BLI_assert(ss->mloop[l_index].v == v_index);
                   UNUSED_VARS_NDEBUG(l_index);
                   const MPoly *mp = &ss->mpoly[p_index];
-                  if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                  if (!use_face_sel || select_poly[p_index]) {
                     const MLoop *ml_other = &ss->mloop[mp->loopstart];
                     for (int k = 0; k < mp->totloop; k++, ml_other++) {
                       const uint v_other_index = ml_other->v;
@@ -3366,8 +3391,7 @@ static void do_vpaint_brush_smear(bContext *C,
                       BLI_assert(ss->mloop[l_index].v == v_index);
                     }
 
-                    const MPoly *mp = &ss->mpoly[p_index];
-                    if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                    if (!use_face_sel || select_poly[p_index]) {
                       /* Get the previous element color */
                       Color color_orig(0, 0, 0, 0); /* unused when array is nullptr */
 
@@ -3413,6 +3437,9 @@ static void calculate_average_color(VPaintData<Color, Traits, domain> *vpd,
 {
   using Blend = typename Traits::BlendType;
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+
   VPaintAverageAccum<Blend> *accum = (VPaintAverageAccum<Blend> *)MEM_mallocN(
       sizeof(*accum) * totnode, __func__);
   blender::threading::parallel_for(IndexRange(totnode), 1LL, [&](IndexRange range) {
@@ -3443,8 +3470,7 @@ static void calculate_average_color(VPaintData<Color, Traits, domain> *vpd,
                                           vd.vert_indices[vd.i];
           if (BKE_brush_curve_strength(brush, 0.0, cache->radius) > 0.0) {
             /* If the vertex is selected for painting. */
-            const MVert *mv = &ss->mvert[v_index];
-            if (!use_vert_sel || mv->flag & SELECT) {
+            if (!use_vert_sel || select_vert[v_index]) {
               accum2->len += gmap->vert_to_loop[v_index].count;
               /* if a vertex is within the brush region, then add its color to the blend. */
               for (int j = 0; j < gmap->vert_to_loop[v_index].count; j++) {
@@ -3529,6 +3555,11 @@ static void vpaint_do_draw(bContext *C,
 
   Color *previous_color = static_cast<Color *>(ss->cache->prev_colors_vpaint);
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  const blender::VArray<bool> select_poly = me->attributes().lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
+
   blender::threading::parallel_for(IndexRange(totnode), 1LL, [&](IndexRange range) {
     for (int n : range) {
       const bool has_grids = (pbvh_type == PBVH_GRIDS);
@@ -3562,10 +3593,9 @@ static void vpaint_do_draw(bContext *C,
           const int v_index = has_grids ? ss->mloop[vd.grid_indices[vd.g]].v :
                                           vd.vert_indices[vd.i];
           const float grid_alpha = has_grids ? 1.0f / vd.gridsize : 1.0f;
-          const MVert *mv = &ss->mvert[v_index];
 
           /* If the vertex is selected for painting. */
-          if (!use_vert_sel || mv->flag & SELECT) {
+          if (!use_vert_sel || select_vert[v_index]) {
             /* Calc the dot prod. between ray norm on surf and current vert
              * (ie splash prevention factor), and only paint front facing verts. */
             float brush_strength = cache->bstrength;
@@ -3617,8 +3647,7 @@ static void vpaint_do_draw(bContext *C,
                   const int p_index = gmap->vert_to_poly[v_index].indices[j];
                   const int l_index = gmap->vert_to_loop[v_index].indices[j];
                   BLI_assert(ss->mloop[l_index].v == v_index);
-                  const MPoly *mp = &ss->mpoly[p_index];
-                  if (!use_face_sel || mp->flag & ME_FACE_SEL) {
+                  if (!use_face_sel || select_poly[p_index]) {
                     Color color_orig = Color(0, 0, 0, 0); /* unused when array is nullptr */
 
                     if (previous_color != nullptr) {
@@ -4045,6 +4074,11 @@ static bool vertex_color_set(Object *ob, ColorPaint4f paintcol_in, CustomDataLay
     return false;
   }
 
+  const blender::VArray<bool> select_vert = me->attributes().lookup_or_default<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT, false);
+  const blender::VArray<bool> select_poly = me->attributes().lookup_or_default<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE, false);
+
   Color paintcol = fromFloat<Color>(paintcol_in);
 
   const bool use_face_sel = (me->editflag & ME_EDIT_PAINT_FACE_SEL) != 0;
@@ -4088,21 +4122,20 @@ static bool vertex_color_set(Object *ob, ColorPaint4f paintcol_in, CustomDataLay
   }
   else {
     Color *color_layer = static_cast<Color *>(layer->data);
-    const Span<MVert> verts = me->verts();
     const Span<MPoly> polys = me->polys();
     const Span<MLoop> loops = me->loops();
 
     for (const int i : polys.index_range()) {
-      const MPoly &poly = polys[i];
-      if (use_face_sel && !(poly.flag & ME_FACE_SEL)) {
+      if (use_face_sel && !select_poly[i]) {
         continue;
       }
+      const MPoly &poly = polys[i];
 
       int j = 0;
       do {
         uint vidx = loops[poly.loopstart + j].v;
 
-        if (!(use_vert_sel && !(verts[vidx].flag & SELECT))) {
+        if (!(use_vert_sel && !(select_vert[vidx]))) {
           if constexpr (domain == ATTR_DOMAIN_CORNER) {
             color_layer[poly.loopstart + j] = paintcol;
           }
diff --git a/source/blender/editors/sculpt_paint/paint_vertex_color_ops.cc b/source/blender/editors/sculpt_paint/paint_vertex_color_ops.cc
index a8e64462a2a..a284d1608cb 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex_color_ops.cc
+++ b/source/blender/editors/sculpt_paint/paint_vertex_color_ops.cc
@@ -159,29 +159,19 @@ static IndexMask get_selected_indices(const Mesh &mesh,
                                       Vector<int64_t> &indices)
 {
   using namespace blender;
-  const Span<MVert> verts = mesh.verts();
-  const Span<MPoly> polys = mesh.polys();
-
-  bke::AttributeAccessor attributes = mesh.attributes();
+  const bke::AttributeAccessor attributes = mesh.attributes();
 
   if (mesh.editflag & ME_EDIT_PAINT_FACE_SEL) {
-    const VArray<bool> selection = attributes.adapt_domain(
-        VArray<bool>::ForFunc(polys.size(),
-                              [&](const int i) { return polys[i].flag & ME_FACE_SEL; }),
-        ATTR_DOMAIN_FACE,
-        domain);
-
+    const VArray<bool> selection = attributes.lookup_or_default<bool>(
+        ".select_poly", ATTR_DOMAIN_FACE, false);
     return index_mask_ops::find_indices_from_virtual_array(
-        IndexMask(attributes.domain_size(domain)), selection, 4096, indices);
+        selection.index_range(), selection, 4096, indices);
   }
   if (mesh.editflag & ME_EDIT_PAINT_VERT_SEL) {
-    const VArray<bool> selection = attributes.adapt_domain(
-        VArray<bool>::ForFunc(verts.size(), [&](const int i) { return verts[i].flag & SELECT; }),
-        ATTR_DOMAIN_POINT,
-        domain);
-
+    const VArray<bool> selection = attributes.lookup_or_default<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT, false);
     return index_mask_ops::find_indices_from_virtual_array(
-        IndexMask(attributes.domain_size(domain)), selection, 4096, indices);
+        selection.index_range(), selection, 4096, indices);
   }
   return IndexMask(attributes.domain_size(domain));
 }
diff --git a/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c b/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
index 0a0d7cff214..a7f43830e6b 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
@@ -445,7 +445,6 @@ static bool weight_paint_set(Object *ob, float paintweight)
   /* mutually exclusive, could be made into a */
   const short paint_selmode = ME_EDIT_PAINT_SEL_MODE(me);
 
-  const MVert *verts = BKE_mesh_verts(me);
   const MPoly *polys = BKE_mesh_polys(me);
   const MLoop *loops = BKE_mesh_loops(me);
   MDeformVert *dvert = BKE_mesh_deform_verts_for_write(me);
@@ -464,10 +463,15 @@ static bool weight_paint_set(Object *ob, float paintweight)
   struct WPaintPrev wpp;
   wpaint_prev_create(&wpp, dvert, me->totvert);
 
+  const bool *select_vert = (const bool *)CustomData_get_layer_named(
+      &me->vdata, CD_PROP_BOOL, ".select_vert");
+  const bool *select_poly = (const bool *)CustomData_get_layer_named(
+      &me->pdata, CD_PROP_BOOL, ".select_poly");
+
   for (index = 0, mp = polys; index < me->totpoly; index++, mp++) {
     uint fidx = mp->totloop - 1;
 
-    if ((paint_selmode == SCE_SELECT_FACE) && !(mp->flag & ME_FACE_SEL)) {
+    if ((paint_selmode == SCE_SELECT_FACE) && !(select_poly && select_poly[index])) {
       continue;
     }
 
@@ -475,7 +479,7 @@ static bool weight_paint_set(Object *ob, float paintweight)
       uint vidx = loops[mp->loopstart + fidx].v;
 
       if (!dvert[vidx].flag) {
-        if ((paint_selmode == SCE_SELECT_VERTEX) && !(verts[vidx].flag & SELECT)) {
+        if ((paint_selmode == SCE_SELECT_VERTEX) && !(select_vert && select_vert[vidx])) {
           continue;
         }
 
diff --git a/source/blender/editors/space_view3d/view3d_select.cc b/source/blender/editors/space_view3d/view3d_select.cc
index 447bf99b000..a0b3802076a 100644
--- a/source/blender/editors/space_view3d/view3d_select.cc
+++ b/source/blender/editors/space_view3d/view3d_select.cc
@@ -45,6 +45,7 @@
 
 #include "BKE_action.h"
 #include "BKE_armature.h"
+#include "BKE_attribute.hh"
 #include "BKE_context.h"
 #include "BKE_curve.h"
 #include "BKE_editmesh.h"
@@ -337,28 +338,29 @@ static bool edbm_backbuf_check_and_select_verts_obmode(Mesh *me,
                                                        EditSelectBuf_Cache *esel,
                                                        const eSelectOp sel_op)
 {
-  MVert *verts = BKE_mesh_verts_for_write(me);
-  MVert *mv = verts;
+  using namespace blender;
   bool changed = false;
 
   const BLI_bitmap *select_bitmap = esel->select_bitmap;
 
-  if (mv) {
-    const bool *hide_vert = (const bool *)CustomData_get_layer_named(
-        &me->vdata, CD_PROP_BOOL, ".hide_vert");
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
+  const VArray<bool> hide_vert = attributes.lookup_or_default<bool>(
+      ".hide_vert", ATTR_DOMAIN_POINT, false);
 
-    for (int index = 0; index < me->totvert; index++, mv++) {
-      if (!(hide_vert && hide_vert[index])) {
-        const bool is_select = mv->flag & SELECT;
-        const bool is_inside = BLI_BITMAP_TEST_BOOL(select_bitmap, index);
-        const int sel_op_result = ED_select_op_action_deselected(sel_op, is_select, is_inside);
-        if (sel_op_result != -1) {
-          SET_FLAG_FROM_TEST(mv->flag, sel_op_result, SELECT);
-          changed = true;
-        }
+  for (int index = 0; index < me->totvert; index++) {
+    if (!hide_vert[index]) {
+      const bool is_select = select_vert.span[index];
+      const bool is_inside = BLI_BITMAP_TEST_BOOL(select_bitmap, index);
+      const int sel_op_result = ED_select_op_action_deselected(sel_op, is_select, is_inside);
+      if (sel_op_result != -1) {
+        select_vert.span[index] = sel_op_result == 1;
+        changed = true;
       }
     }
   }
+  select_vert.finish();
   return changed;
 }
 
@@ -367,27 +369,29 @@ static bool edbm_backbuf_check_and_select_faces_obmode(Mesh *me,
                                                        EditSelectBuf_Cache *esel,
                                                        const eSelectOp sel_op)
 {
-  MPoly *polys = BKE_mesh_polys_for_write(me);
+  using namespace blender;
   bool changed = false;
 
   const BLI_bitmap *select_bitmap = esel->select_bitmap;
 
-  if (polys) {
-    const bool *hide_poly = (const bool *)CustomData_get_layer_named(
-        &me->vdata, CD_PROP_BOOL, ".hide_poly");
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+  bke::SpanAttributeWriter<bool> select_poly = attributes.lookup_or_add_for_write_span<bool>(
+      ".select_poly", ATTR_DOMAIN_FACE);
+  const VArray<bool> hide_poly = attributes.lookup_or_default<bool>(
+      ".hide_poly", ATTR_DOMAIN_FACE, false);
 
-    for (int index = 0; index < me->totpoly; index++) {
-      if (!(hide_poly && hide_poly[index])) {
-        const bool is_select = polys[index].flag & ME_FACE_SEL;
-        const bool is_inside = BLI_BITMAP_TEST_BOOL(select_bitmap, index);
-        const int sel_op_result = ED_select_op_action_deselected(sel_op, is_select, is_inside);
-        if (sel_op_result != -1) {
-          SET_FLAG_FROM_TEST(polys[index].flag, sel_op_result, ME_FACE_SEL);
-          changed = true;
-        }
+  for (int index = 0; index < me->totpoly; index++) {
+    if (!hide_poly[index]) {
+      const bool is_select = select_poly.span[index];
+      const bool is_inside = BLI_BITMAP_TEST_BOOL(select_bitmap, index);
+      const int sel_op_result = ED_select_op_action_deselected(sel_op, is_select, is_inside);
+      if (sel_op_result != -1) {
+        select_poly.span[index] = sel_op_result == 1;
+        changed = true;
       }
     }
   }
+  select_poly.finish();
   return changed;
 }
 
@@ -1154,20 +1158,27 @@ static bool do_lasso_select_meta(ViewContext *vc,
   return data.is_changed;
 }
 
+struct LassoSelectUserData_ForMeshVert {
+  LassoSelectUserData lasso_data;
+  blender::MutableSpan<bool> select_vert;
+};
 static void do_lasso_select_meshobject__doSelectVert(void *userData,
-                                                     MVert *mv,
+                                                     MVert * /*mv*/,
                                                      const float screen_co[2],
-                                                     int UNUSED(index))
+                                                     int index)
 {
-  LassoSelectUserData *data = static_cast<LassoSelectUserData *>(userData);
-  const bool is_select = mv->flag & SELECT;
+  using namespace blender;
+  LassoSelectUserData_ForMeshVert *mesh_data = static_cast<LassoSelectUserData_ForMeshVert *>(
+      userData);
+  LassoSelectUserData *data = &mesh_data->lasso_data;
+  const bool is_select = mesh_data->select_vert[index];
   const bool is_inside =
       (BLI_rctf_isect_pt_v(data->rect_fl, screen_co) &&
        BLI_lasso_is_point_inside(
            data->mcoords, data->mcoords_len, screen_co[0], screen_co[1], IS_CLIPPED));
   const int sel_op_result = ED_select_op_action_deselected(data->sel_op, is_select, is_inside);
   if (sel_op_result != -1) {
-    SET_FLAG_FROM_TEST(mv->flag, sel_op_result, SELECT);
+    mesh_data->select_vert[index] = sel_op_result == 1;
     data->is_changed = true;
   }
 }
@@ -1177,6 +1188,7 @@ static bool do_lasso_select_paintvert(ViewContext *vc,
                                       const int mcoords_len,
                                       const eSelectOp sel_op)
 {
+  using namespace blender;
   const bool use_zbuf = !XRAY_ENABLED(vc->v3d);
   Object *ob = vc->obact;
   Mesh *me = static_cast<Mesh *>(ob->data);
@@ -1210,16 +1222,22 @@ static bool do_lasso_select_paintvert(ViewContext *vc,
     }
   }
   else {
-    LassoSelectUserData data;
+    bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+    bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT);
+
+    LassoSelectUserData_ForMeshVert data;
+    data.select_vert = select_vert.span;
 
-    view3d_userdata_lassoselect_init(&data, vc, &rect, mcoords, mcoords_len, sel_op);
+    view3d_userdata_lassoselect_init(&data.lasso_data, vc, &rect, mcoords, mcoords_len, sel_op);
 
     ED_view3d_init_mats_rv3d(vc->obact, vc->rv3d);
 
     meshobject_foreachScreenVert(
         vc, do_lasso_select_meshobject__doSelectVert, &data, V3D_PROJ_TEST_CLIP_DEFAULT);
 
-    changed |= data.is_changed;
+    changed |= data.lasso_data.is_changed;
+    select_vert.finish();
   }
 
   if (changed) {
@@ -2825,20 +2843,22 @@ static bool ed_wpaint_vertex_select_pick(bContext *C,
                                          const SelectPick_Params *params,
                                          Object *obact)
 {
+  using namespace blender;
   View3D *v3d = CTX_wm_view3d(C);
   const bool use_zbuf = !XRAY_ENABLED(v3d);
 
   Mesh *me = static_cast<Mesh *>(obact->data); /* already checked for nullptr */
   uint index = 0;
-  MVert *verts = BKE_mesh_verts_for_write(me);
-
-  MVert *mv;
   bool changed = false;
 
   bool found = ED_mesh_pick_vert(C, obact, mval, ED_MESH_PICK_DEFAULT_VERT_DIST, use_zbuf, &index);
 
+  bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+  bke::AttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write<bool>(
+      ".select_vert", ATTR_DOMAIN_POINT);
+
   if (params->sel_op == SEL_OP_SET) {
-    if ((found && params->select_passthrough) && (verts[index].flag & SELECT)) {
+    if ((found && params->select_passthrough) && select_vert.varray[index]) {
       found = false;
     }
     else if (found || params->deselect_all) {
@@ -2848,23 +2868,22 @@ static bool ed_wpaint_vertex_select_pick(bContext *C,
   }
 
   if (found) {
-    mv = &verts[index];
     switch (params->sel_op) {
       case SEL_OP_ADD: {
-        mv->flag |= SELECT;
+        select_vert.varray.set(index, true);
         break;
       }
       case SEL_OP_SUB: {
-        mv->flag &= ~SELECT;
+        select_vert.varray.set(index, false);
         break;
       }
       case SEL_OP_XOR: {
-        mv->flag ^= SELECT;
+        select_vert.varray.set(index, !select_vert.varray[index]);
         break;
       }
       case SEL_OP_SET: {
         paintvert_deselect_all_visible(obact, SEL_DESELECT, false);
-        mv->flag |= SELECT;
+        select_vert.varray.set(index, true);
         break;
       }
       case SEL_OP_AND: {
@@ -2874,13 +2893,15 @@ static bool ed_wpaint_vertex_select_pick(bContext *C,
     }
 
     /* update mselect */
-    if (mv->flag & SELECT) {
+    if (select_vert.varray[index]) {
       BKE_mesh_mselect_active_set(me, index, ME_VSEL);
     }
     else {
       BKE_mesh_mselect_validate(me);
     }
 
+    select_vert.finish();
+
     paintvert_flush_flags(obact);
 
     changed = true;
@@ -3117,17 +3138,23 @@ bool edge_inside_circle(const float cent[2],
   return (dist_squared_to_line_segment_v2(cent, screen_co_a, screen_co_b) < radius_squared);
 }
 
+struct BoxSelectUserData_ForMeshVert {
+  BoxSelectUserData box_data;
+  blender::MutableSpan<bool> select_vert;
+};
 static void do_paintvert_box_select__doSelectVert(void *userData,
-                                                  MVert *mv,
+                                                  MVert * /*mv*/,
                                                   const float screen_co[2],
-                                                  int UNUSED(index))
+                                                  int index)
 {
-  BoxSelectUserData *data = static_cast<BoxSelectUserData *>(userData);
-  const bool is_select = mv->flag & SELECT;
+  BoxSelectUserData_ForMeshVert *mesh_data = static_cast<BoxSelectUserData_ForMeshVert *>(
+      userData);
+  BoxSelectUserData *data = &mesh_data->box_data;
+  const bool is_select = mesh_data->select_vert[index];
   const bool is_inside = BLI_rctf_isect_pt_v(data->rect_fl, screen_co);
   const int sel_op_result = ED_select_op_action_deselected(data->sel_op, is_select, is_inside);
   if (sel_op_result != -1) {
-    SET_FLAG_FROM_TEST(mv->flag, sel_op_result, SELECT);
+    mesh_data->select_vert[index] = sel_op_result == 1;
     data->is_changed = true;
   }
 }
@@ -3136,6 +3163,7 @@ static bool do_paintvert_box_select(ViewContext *vc,
                                     const rcti *rect,
                                     const eSelectOp sel_op)
 {
+  using namespace blender;
   const bool use_zbuf = !XRAY_ENABLED(vc->v3d);
 
   Mesh *me = static_cast<Mesh *>(vc->obact->data);
@@ -3164,15 +3192,21 @@ static bool do_paintvert_box_select(ViewContext *vc,
     }
   }
   else {
-    BoxSelectUserData data;
+    bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+    bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT);
 
-    view3d_userdata_boxselect_init(&data, vc, rect, sel_op);
+    BoxSelectUserData_ForMeshVert data;
+    data.select_vert = select_vert.span;
+
+    view3d_userdata_boxselect_init(&data.box_data, vc, rect, sel_op);
 
     ED_view3d_init_mats_rv3d(vc->obact, vc->rv3d);
 
     meshobject_foreachScreenVert(
         vc, do_paintvert_box_select__doSelectVert, &data, V3D_PROJ_TEST_CLIP_DEFAULT);
-    changed |= data.is_changed;
+    changed |= data.box_data.is_changed;
+    select_vert.finish();
   }
 
   if (changed) {
@@ -4124,15 +4158,21 @@ static bool paint_facesel_circle_select(ViewContext *vc,
   return changed;
 }
 
+struct CircleSelectUserData_ForMeshVert {
+  CircleSelectUserData circle_data;
+  blender::MutableSpan<bool> select_vert;
+};
 static void paint_vertsel_circle_select_doSelectVert(void *userData,
-                                                     MVert *mv,
+                                                     MVert * /*mv*/,
                                                      const float screen_co[2],
-                                                     int UNUSED(index))
+                                                     int index)
 {
-  CircleSelectUserData *data = static_cast<CircleSelectUserData *>(userData);
+  CircleSelectUserData_ForMeshVert *mesh_data = static_cast<CircleSelectUserData_ForMeshVert *>(
+      userData);
+  CircleSelectUserData *data = &mesh_data->circle_data;
 
   if (len_squared_v2v2(data->mval_fl, screen_co) <= data->radius_squared) {
-    SET_FLAG_FROM_TEST(mv->flag, data->select, SELECT);
+    mesh_data->select_vert[index] = data->select;
     data->is_changed = true;
   }
 }
@@ -4142,6 +4182,7 @@ static bool paint_vertsel_circle_select(ViewContext *vc,
                                         const int mval[2],
                                         float rad)
 {
+  using namespace blender;
   BLI_assert(ELEM(sel_op, SEL_OP_SET, SEL_OP_ADD, SEL_OP_SUB));
   const bool use_zbuf = !XRAY_ENABLED(vc->v3d);
   Object *ob = vc->obact;
@@ -4173,14 +4214,20 @@ static bool paint_vertsel_circle_select(ViewContext *vc,
     }
   }
   else {
-    CircleSelectUserData data;
+    bke::MutableAttributeAccessor attributes = me->attributes_for_write();
+    bke::SpanAttributeWriter<bool> select_vert = attributes.lookup_or_add_for_write_span<bool>(
+        ".select_vert", ATTR_DOMAIN_POINT);
+
+    CircleSelectUserData_ForMeshVert data;
+    data.select_vert = select_vert.span;
 
     ED_view3d_init_mats_rv3d(vc->obact, vc->rv3d); /* for foreach's screen/vert projection */
 
-    view3d_userdata_circleselect_init(&data, vc, select, mval, rad);
+    view3d_userdata_circleselect_init(&data.circle_data, vc, select, mval, rad);
     meshobject_foreachScreenVert(
         vc, paint_vertsel_circle_select_doSelectVert, &data, V3D_PROJ_TEST_CLIP_DEFAULT);
-    changed |= data.is_changed;
+    changed |= data.circle_data.is_changed;
+    select_vert.finish();
   }
 
   if (changed) {