Fix Face Sets painting and selection precision

This fixes the following issues:
- Previously, the face set from the active vertex was used directly. Vertices always return the most recently created face set, so in some cases there may be some face sets that were not possible to select as active. Now the active face set is set in the ray intersection, so it always matches the face under the cursor.
- When drawing face sets they were set per vertex, so it was not possible to paint one face at a time. Now face sets are painted per poly when using the brush on meshes, testing the distance to the center of each poly.
- The code for the active vertex on PBVH_GRIDS was not correct, so I also fixed that to test if everything was working correctly.
{F8441699}

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7303

1 files changed, 78 insertions, 15 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index dbb89617b08..91c8262dd67 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -216,6 +216,22 @@ static void SCULPT_active_vertex_normal_get(SculptSession *ss, float normal[3])
 
 /* Sculpt Face Sets and Visibility. */
 
+static int SCULPT_active_face_set_get(SculptSession *ss)
+{
+  switch (BKE_pbvh_type(ss->pbvh)) {
+    case PBVH_FACES:
+      return ss->face_sets[ss->active_face_index];
+    case PBVH_GRIDS: {
+      const int face_index = BKE_subdiv_cgg_grid_to_face_index(ss->subdiv_ccg,
+                                                               ss->active_grid_index);
+      return ss->face_sets[face_index];
+    }
+    case PBVH_BMESH:
+      return SCULPT_FACE_SET_NONE;
+  }
+  return SCULPT_FACE_SET_NONE;
+}
+
 static void SCULPT_vertex_visible_set(SculptSession *ss, int index, bool visible)
 {
   switch (BKE_pbvh_type(ss->pbvh)) {
@@ -2997,6 +3013,8 @@ typedef struct {
   int active_vertex_index;
   float *face_normal;
 
+  int active_face_grid_index;
+
   struct IsectRayPrecalc isect_precalc;
 } SculptRaycastData;
 
@@ -3641,19 +3659,49 @@ static void do_draw_face_sets_brush_task_cb_ex(void *__restrict userdata,
 
   BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
   {
-    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
-      const float fade = bstrength * SCULPT_brush_strength_factor(ss,
-                                                                  brush,
-                                                                  vd.co,
-                                                                  sqrtf(test.dist),
-                                                                  vd.no,
-                                                                  vd.fno,
-                                                                  vd.mask ? *vd.mask : 0.0f,
-                                                                  vd.index,
-                                                                  tls->thread_id);
+    if (BKE_pbvh_type(ss->pbvh) == PBVH_FACES) {
+      MeshElemMap *vert_map = &ss->pmap[vd.index];
+      for (int j = 0; j < ss->pmap[vd.index].count; j++) {
+        const MPoly *p = &ss->mpoly[vert_map->indices[j]];
 
-      if (fade > 0.05f) {
-        SCULPT_vertex_face_set_set(ss, vd.index, ss->cache->paint_face_set);
+        float poly_center[3];
+        BKE_mesh_calc_poly_center(p, &ss->mloop[p->loopstart], ss->mvert, poly_center);
+
+        if (sculpt_brush_test_sq_fn(&test, poly_center)) {
+          const float fade = bstrength * SCULPT_brush_strength_factor(ss,
+                                                                      brush,
+                                                                      vd.co,
+                                                                      sqrtf(test.dist),
+                                                                      vd.no,
+                                                                      vd.fno,
+                                                                      vd.mask ? *vd.mask : 0.0f,
+                                                                      vd.index,
+                                                                      tls->thread_id);
+
+          if (fade > 0.05f && ss->face_sets[vert_map->indices[j]] > 0) {
+            ss->face_sets[vert_map->indices[j]] = abs(ss->cache->paint_face_set);
+          }
+        }
+      }
+    }
+
+    else if (BKE_pbvh_type(ss->pbvh) == PBVH_GRIDS) {
+      {
+        if (sculpt_brush_test_sq_fn(&test, vd.co)) {
+          const float fade = bstrength * SCULPT_brush_strength_factor(ss,
+                                                                      brush,
+                                                                      vd.co,
+                                                                      sqrtf(test.dist),
+                                                                      vd.no,
+                                                                      vd.fno,
+                                                                      vd.mask ? *vd.mask : 0.0f,
+                                                                      vd.index,
+                                                                      tls->thread_id);
+
+          if (fade > 0.05f) {
+            SCULPT_vertex_face_set_set(ss, vd.index, ss->cache->paint_face_set);
+          }
+        }
       }
     }
   }
@@ -3714,7 +3762,7 @@ static void do_draw_face_sets_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, in
       ss->cache->radial_symmetry_pass == 0) {
     if (ss->cache->invert) {
       /* When inverting the brush, pick the paint face mask ID from the mesh. */
-      ss->cache->paint_face_set = SCULPT_vertex_face_set_get(ss, SCULPT_active_vertex_get(ss));
+      ss->cache->paint_face_set = SCULPT_active_face_set_get(ss);
     }
     else {
       /* By default create a new Face Sets. */
@@ -7440,6 +7488,7 @@ static void sculpt_raycast_cb(PBVHNode *node, void *data_v, float *tmin)
                               &srd->isect_precalc,
                               &srd->depth,
                               &srd->active_vertex_index,
+                              &srd->active_face_grid_index,
                               srd->face_normal)) {
       srd->hit = true;
       *tmin = srd->depth;
@@ -7590,6 +7639,21 @@ bool SCULPT_cursor_geometry_info_update(bContext *C,
   ss->active_vertex_index = srd.active_vertex_index;
   copy_v3_v3(out->active_vertex_co, SCULPT_active_vertex_co_get(ss));
 
+  switch (BKE_pbvh_type(ss->pbvh)) {
+    case PBVH_FACES:
+      ss->active_face_index = srd.active_face_grid_index;
+      ss->active_grid_index = 0;
+      break;
+    case PBVH_GRIDS:
+      ss->active_face_index = 0;
+      ss->active_grid_index = srd.active_face_grid_index;
+      break;
+    case PBVH_BMESH:
+      ss->active_face_index = 0;
+      ss->active_grid_index = 0;
+      break;
+  }
+
   copy_v3_v3(out->location, ray_normal);
   mul_v3_fl(out->location, srd.depth);
   add_v3_v3(out->location, ray_start);
@@ -11710,8 +11774,7 @@ static int sculpt_face_sets_change_visibility_invoke(bContext *C,
 
   const int tot_vert = SCULPT_vertex_count_get(ss);
   const int mode = RNA_enum_get(op->ptr, "mode");
-  int active_vertex_index = SCULPT_active_vertex_get(ss);
-  int active_face_set = SCULPT_vertex_face_set_get(ss, active_vertex_index);
+  const int active_face_set = SCULPT_active_face_set_get(ss);
 
   SCULPT_undo_push_begin("Hide area");