Sculpt Face Sets

Face Sets are the new system to control the visibility state of the mesh in sculpt and paint modes. They are designed to work in modes where brushes are the primary way of interaction and they provide much more control when working with meshes with complex shapes and overlapping surfaces.

This initial commit includes:
- Sculpt Face Sets data structures and PBVH rendering.
- Face Set overlay and opacity controls.
- Sculpt Undo support.
- Remesher reprojection support. The visibility state of the mesh is also preserved when remeshing.
- Automasking and Mesh filter support.
- Mask expand operator mode to expand Face Sets (Shift + W) and flood fill areas by connectivity (press Ctrl while expanding).
- Sculpt Mode Face Sets and Visibility API.
- Sculpt Face Sets creation and visibility management operators.
- Operator to randomize the Face Sets colors.
- Draw Face Sets brush tool to create and edit the Face Sets. Drawing on the mesh creates a new Face Set. Pressing Ctrl before drawing modifies the Face Set under the brush at the beginning of the stroke.
- Updated keymap and menu to work with Face Sets from Sculpt Mode (H to toggle visibility, Alt + H to show all, Shit + H to hide).
- Pie menu on the W key with Face common Sets operations.

Know limitations:
- Multires support. The Face Sets and Visibility API needs to be implemented for Multires.

Reviewed By: jbakker, #user_interface, Severin

Differential Revision: https://developer.blender.org/D6070

1 files changed, 75 insertions, 6 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_undo.c b/source/blender/editors/sculpt_paint/sculpt_undo.c
index 044d5b3c0b0..d1896f47c52 100644
--- a/source/blender/editors/sculpt_paint/sculpt_undo.c
+++ b/source/blender/editors/sculpt_paint/sculpt_undo.c
@@ -79,8 +79,7 @@ static void update_cb(PBVHNode *node, void *rebuild)
   BKE_pbvh_node_mark_update(node);
   BKE_pbvh_node_mark_update_mask(node);
   if (*((bool *)rebuild)) {
-    BKE_pbvh_node_mark_rebuild_draw(node);
-    BKE_pbvh_node_mark_visibility_update(node);
+    BKE_pbvh_node_mark_update_visibility(node);
   }
   BKE_pbvh_node_fully_hidden_set(node, 0);
 }
@@ -332,6 +331,15 @@ static bool sculpt_undo_restore_mask(bContext *C, SculptUndoNode *unode)
   return true;
 }
 
+static bool sculpt_undo_restore_face_sets(bContext *C, SculptUndoNode *unode)
+{
+  ViewLayer *view_layer = CTX_data_view_layer(C);
+  Object *ob = OBACT(view_layer);
+  SculptSession *ss = ob->sculpt;
+  memcpy(ss->face_sets, unode->face_sets, ss->totpoly * sizeof(int));
+  return false;
+}
+
 static void sculpt_undo_bmesh_restore_generic_task_cb(
     void *__restrict userdata, const int n, const TaskParallelTLS *__restrict UNUSED(tls))
 {
@@ -533,6 +541,30 @@ static void sculpt_undo_restore_list(bContext *C, Depsgraph *depsgraph, ListBase
       BKE_sculpt_update_object_for_edit(depsgraph, ob, false, need_mask);
       return;
     }
+    else if (unode->type == SCULPT_UNDO_FACE_SETS) {
+
+      sculpt_undo_restore_face_sets(C, unode);
+
+      rebuild = true;
+      BKE_pbvh_search_callback(ss->pbvh, NULL, NULL, update_cb, &rebuild);
+
+      BKE_sculpt_update_object_for_edit(depsgraph, ob, true, need_mask);
+
+      sculpt_visibility_sync_all_face_sets_to_vertices(ss);
+      BKE_pbvh_update_vertex_data(ss->pbvh, PBVH_UpdateVisibility);
+
+      if (BKE_pbvh_type(ss->pbvh) == PBVH_FACES) {
+        BKE_mesh_flush_hidden_from_verts(ob->data);
+      }
+
+      if (!BKE_sculptsession_use_pbvh_draw(ob, v3d)) {
+        DEG_id_tag_update(&ob->id, ID_RECALC_SHADING);
+        DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
+      }
+
+      unode->applied = true;
+      return;
+    }
   }
 
   BKE_sculpt_update_object_for_edit(depsgraph, ob, false, need_mask);
@@ -584,6 +616,8 @@ static void sculpt_undo_restore_list(bContext *C, Depsgraph *depsgraph, ListBase
           update_mask = true;
         }
         break;
+      case SCULPT_UNDO_FACE_SETS:
+        break;
 
       case SCULPT_UNDO_DYNTOPO_BEGIN:
       case SCULPT_UNDO_DYNTOPO_END:
@@ -619,10 +653,16 @@ static void sculpt_undo_restore_list(bContext *C, Depsgraph *depsgraph, ListBase
     };
     BKE_pbvh_search_callback(ss->pbvh, NULL, NULL, update_cb_partial, &data);
     BKE_pbvh_update_bounds(ss->pbvh, PBVH_UpdateBB | PBVH_UpdateOriginalBB | PBVH_UpdateRedraw);
+
     if (update_mask) {
       BKE_pbvh_update_vertex_data(ss->pbvh, PBVH_UpdateMask);
     }
 
+    if (update_visibility) {
+      sculpt_visibility_sync_all_vertex_to_face_sets(ss);
+      BKE_pbvh_update_visibility(ss->pbvh);
+    }
+
     if (BKE_sculpt_multires_active(scene, ob)) {
       if (rebuild) {
         multires_mark_as_modified(depsgraph, ob, MULTIRES_HIDDEN_MODIFIED);
@@ -642,10 +682,6 @@ static void sculpt_undo_restore_list(bContext *C, Depsgraph *depsgraph, ListBase
       BKE_sculptsession_free_deformMats(ss);
     }
 
-    if (update_visibility) {
-      BKE_pbvh_update_visibility(ss->pbvh);
-    }
-
     if (BKE_pbvh_type(ss->pbvh) == PBVH_FACES && update_visibility) {
       Mesh *mesh = ob->data;
       BKE_mesh_flush_hidden_from_verts(mesh);
@@ -714,6 +750,10 @@ static void sculpt_undo_free_list(ListBase *lb)
       CustomData_free(&unode->geom_pdata, unode->geom_totpoly);
     }
 
+    if (unode->face_sets) {
+      MEM_freeN(unode->face_sets);
+    }
+
     MEM_freeN(unode);
 
     unode = unode_next;
@@ -828,6 +868,7 @@ static SculptUndoNode *sculpt_undo_alloc_node(Object *ob, PBVHNode *node, Sculpt
     case SCULPT_UNDO_DYNTOPO_SYMMETRIZE:
       BLI_assert(!"Dynamic topology should've already been handled");
     case SCULPT_UNDO_GEOMETRY:
+    case SCULPT_UNDO_FACE_SETS:
       break;
   }
 
@@ -939,6 +980,27 @@ static SculptUndoNode *sculpt_undo_geometry_push(Object *ob, SculptUndoType type
   return unode;
 }
 
+static SculptUndoNode *sculpt_undo_face_sets_push(Object *ob, SculptUndoType type)
+{
+  UndoSculpt *usculpt = sculpt_undo_get_nodes();
+  SculptSession *ss = ob->sculpt;
+
+  SculptUndoNode *unode = usculpt->nodes.first;
+
+  unode = MEM_callocN(sizeof(*unode), __func__);
+
+  BLI_strncpy(unode->idname, ob->id.name, sizeof(unode->idname));
+  unode->type = type;
+  unode->applied = true;
+
+  unode->face_sets = MEM_callocN(ss->totpoly * sizeof(int), "sculpt face sets");
+  memcpy(unode->face_sets, ss->face_sets, ss->totpoly * sizeof(int));
+
+  BLI_addtail(&usculpt->nodes, unode);
+
+  return unode;
+}
+
 static SculptUndoNode *sculpt_undo_bmesh_push(Object *ob, PBVHNode *node, SculptUndoType type)
 {
   UndoSculpt *usculpt = sculpt_undo_get_nodes();
@@ -1022,6 +1084,7 @@ static SculptUndoNode *sculpt_undo_bmesh_push(Object *ob, PBVHNode *node, Sculpt
       case SCULPT_UNDO_DYNTOPO_END:
       case SCULPT_UNDO_DYNTOPO_SYMMETRIZE:
       case SCULPT_UNDO_GEOMETRY:
+      case SCULPT_UNDO_FACE_SETS:
         break;
     }
   }
@@ -1051,6 +1114,11 @@ SculptUndoNode *sculpt_undo_push_node(Object *ob, PBVHNode *node, SculptUndoType
     BLI_thread_unlock(LOCK_CUSTOM1);
     return unode;
   }
+  else if (type == SCULPT_UNDO_FACE_SETS) {
+    unode = sculpt_undo_face_sets_push(ob, type);
+    BLI_thread_unlock(LOCK_CUSTOM1);
+    return unode;
+  }
   else if ((unode = sculpt_undo_get_node(node))) {
     BLI_thread_unlock(LOCK_CUSTOM1);
     return unode;
@@ -1091,6 +1159,7 @@ SculptUndoNode *sculpt_undo_push_node(Object *ob, PBVHNode *node, SculptUndoType
     case SCULPT_UNDO_DYNTOPO_SYMMETRIZE:
       BLI_assert(!"Dynamic topology should've already been handled");
     case SCULPT_UNDO_GEOMETRY:
+    case SCULPT_UNDO_FACE_SETS:
       break;
   }