Fix T78664: Implement Mesh and Face Set boundary automasking in Multires

This implements the SCULPT_vertex_is_boundary and SCULPT_vertex_has_unique_face_set functions for PBVH_GRIDS, which makes features such as automasking now work in multires. It also fixes some other face sets related features in multires, like face set boundary smoothing.

This uses the BKE_subdiv_ccg_coarse_mesh_adjacency_info_get function to get the vertex indicies in the base mesh from multires. This way the API functions can get topology or face set information directly from it. In the future, these vertex indices can be used to get any other information from the base mesh from multires, like seams, sharp edges, disconnected elements IDs...

Reviewed By: sergey

Maniphest Tasks: T78664

Differential Revision: https://developer.blender.org/D8227

1 files changed, 55 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/subdiv_ccg.c b/source/blender/blenkernel/intern/subdiv_ccg.c
index a1e218390c3..22649a2af07 100644
--- a/source/blender/blenkernel/intern/subdiv_ccg.c
+++ b/source/blender/blenkernel/intern/subdiv_ccg.c
@@ -1834,4 +1834,59 @@ const int *BKE_subdiv_ccg_start_face_grid_index_get(const SubdivCCG *subdiv_ccg)
   return subdiv_ccg->cache_.start_face_grid_index;
 }
 
+static void adjacet_vertices_index_from_adjacent_edge(const SubdivCCG *subdiv_ccg,
+                                                      const SubdivCCGCoord *coord,
+                                                      const MLoop *mloop,
+                                                      const MPoly *mpoly,
+                                                      int *r_v1,
+                                                      int *r_v2)
+{
+  const int grid_size_1 = subdiv_ccg->grid_size - 1;
+  const int poly_index = BKE_subdiv_ccg_grid_to_face_index(subdiv_ccg, coord->grid_index);
+  const MPoly *p = &mpoly[poly_index];
+  *r_v1 = mloop[coord->grid_index].v;
+  if (coord->x == grid_size_1) {
+    const MLoop *next = ME_POLY_LOOP_NEXT(mloop, p, coord->grid_index);
+    *r_v2 = next->v;
+  }
+  if (coord->y == grid_size_1) {
+    const MLoop *prev = ME_POLY_LOOP_PREV(mloop, p, coord->grid_index);
+    *r_v2 = prev->v;
+  }
+}
+
+SubdivCCGAdjacencyType BKE_subdiv_ccg_coarse_mesh_adjacency_info_get(const SubdivCCG *subdiv_ccg,
+                                                                     const SubdivCCGCoord *coord,
+                                                                     const MLoop *mloop,
+                                                                     const MPoly *mpoly,
+                                                                     int *r_v1,
+                                                                     int *r_v2)
+{
+
+  const int grid_size_1 = subdiv_ccg->grid_size - 1;
+  if (is_corner_grid_coord(subdiv_ccg, coord)) {
+    if (coord->x == 0 && coord->y == 0) {
+      /* Grid corner in the center of a poly. */
+      return SUBDIV_CCG_ADJACENT_NONE;
+    }
+    if (coord->x == grid_size_1 && coord->y == grid_size_1) {
+      /* Grid corner adjacent to a coarse mesh vertex. */
+      *r_v1 = *r_v2 = mloop[coord->grid_index].v;
+      return SUBDIV_CCG_ADJACENT_VERTEX;
+    }
+    /* Grid corner adjacent to the middle of a coarse mesh edge. */
+    adjacet_vertices_index_from_adjacent_edge(subdiv_ccg, coord, mloop, mpoly, r_v1, r_v2);
+    return SUBDIV_CCG_ADJACENT_EDGE;
+  }
+
+  if (is_boundary_grid_coord(subdiv_ccg, coord)) {
+    if (!is_inner_edge_grid_coordinate(subdiv_ccg, coord)) {
+      /* Grid boundary adjacent to a coarse mesh edge. */
+      adjacet_vertices_index_from_adjacent_edge(subdiv_ccg, coord, mloop, mpoly, r_v1, r_v2);
+      return SUBDIV_CCG_ADJACENT_EDGE;
+    }
+  }
+  return SUBDIV_CCG_ADJACENT_NONE;
+}
+
 /** \} */