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, 16 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_subdiv_ccg.h b/source/blender/blenkernel/BKE_subdiv_ccg.h
index 78e91d3ad2f..5808f223f32 100644
--- a/source/blender/blenkernel/BKE_subdiv_ccg.h
+++ b/source/blender/blenkernel/BKE_subdiv_ccg.h
@@ -313,6 +313,22 @@ void BKE_subdiv_ccg_neighbor_coords_get(const SubdivCCG *subdiv_ccg,
 
 int BKE_subdiv_ccg_grid_to_face_index(const SubdivCCG *subdiv_ccg, const int grid_index);
 
+typedef enum SubdivCCGAdjacencyType {
+  SUBDIV_CCG_ADJACENT_NONE,
+  SUBDIV_CCG_ADJACENT_VERTEX,
+  SUBDIV_CCG_ADJACENT_EDGE,
+} SubdivCCGAdjacencyType;
+
+/* Returns if a grid coordinates is adjacent to a coarse mesh edge, vertex or nothing. If it is
+ * adjacent to an edge, r_v1 and r_v2 will be set to the two vertices of that edge. If it is
+ * adjacent to a vertex, r_v1 and r_v2 will be the index of that vertex. */
+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);
+
 /* Get array which is indexed by face index and contains index of a first grid of the face.
  *
  * The "ensure" version allocates the mapping if it's not know yet and stores it in the subdiv_ccg