fix [#36697] Topology mirror causes vertices to jump?

don't give up too early finding unique geometry by keeping track of edges with matching vertex hashes and keep checking for unique topology as long as the total of these edges keeps increasing.

1 files changed, 21 insertions, 10 deletions

diff --git a/source/blender/editors/mesh/editface.c b/source/blender/editors/mesh/editface.c
index 902906fcf8a..7944c2f0cca 100644
--- a/source/blender/editors/mesh/editface.c
+++ b/source/blender/editors/mesh/editface.c
@@ -691,6 +691,7 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 	int a, last;
 	int totvert, totedge;
 	int tot_unique = -1, tot_unique_prev = -1;
+	int tot_unique_edges = 0, tot_unique_edges_prev;
 
 	MirrTopoHash_t *topo_hash = NULL;
 	MirrTopoHash_t *topo_hash_prev = NULL;
@@ -720,36 +721,45 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 		totedge = me->edit_btmesh->bm->totedge;
 
 		BM_ITER_MESH (eed, &iter, em->bm, BM_EDGES_OF_MESH) {
-			topo_hash[BM_elem_index_get(eed->v1)]++;
-			topo_hash[BM_elem_index_get(eed->v2)]++;
+			const int i1 = BM_elem_index_get(eed->v1), i2 = BM_elem_index_get(eed->v2);
+			topo_hash[i1]++;
+			topo_hash[i2]++;
 		}
 	}
 	else {
 		totedge = me->totedge;
 
 		for (a = 0, medge = me->medge; a < me->totedge; a++, medge++) {
-			topo_hash[medge->v1]++;
-			topo_hash[medge->v2]++;
+			const unsigned int i1 = medge->v1, i2 = medge->v2;
+			topo_hash[i1]++;
+			topo_hash[i2]++;
 		}
 	}
 
 	topo_hash_prev = MEM_dupallocN(topo_hash);
 
 	tot_unique_prev = -1;
+	tot_unique_edges_prev = -1;
 	while (1) {
 		/* use the number of edges per vert to give verts unique topology IDs */
 
+		tot_unique_edges = 0;
+
+		/* This can make really big numbers, wrapping around here is fine */
 		if (em) {
 			BM_ITER_MESH (eed, &iter, em->bm, BM_EDGES_OF_MESH) {
-				topo_hash[BM_elem_index_get(eed->v1)] += topo_hash_prev[BM_elem_index_get(eed->v2)] * topo_pass;
-				topo_hash[BM_elem_index_get(eed->v2)] += topo_hash_prev[BM_elem_index_get(eed->v1)] * topo_pass;
+				const int i1 = BM_elem_index_get(eed->v1), i2 = BM_elem_index_get(eed->v2);
+				topo_hash[i1] += topo_hash_prev[i2] * topo_pass;
+				topo_hash[i2] += topo_hash_prev[i1] * topo_pass;
+				tot_unique_edges += (topo_hash[i1] != topo_hash[i2]);
 			}
 		}
 		else {
 			for (a = 0, medge = me->medge; a < me->totedge; a++, medge++) {
-				/* This can make really big numbers, wrapping around here is fine */
-				topo_hash[medge->v1] += topo_hash_prev[medge->v2] * topo_pass;
-				topo_hash[medge->v2] += topo_hash_prev[medge->v1] * topo_pass;
+				const unsigned int i1 = medge->v1, i2 = medge->v2;
+				topo_hash[i1] += topo_hash_prev[i2] * topo_pass;
+				topo_hash[i2] += topo_hash_prev[i1] * topo_pass;
+				tot_unique_edges += (topo_hash[i1] != topo_hash[i2]);
 			}
 		}
 		memcpy(topo_hash_prev, topo_hash, sizeof(MirrTopoHash_t) * totvert);
@@ -764,13 +774,14 @@ void ED_mesh_mirrtopo_init(Mesh *me, const int ob_mode, MirrTopoStore_t *mesh_to
 			}
 		}
 
-		if (tot_unique <= tot_unique_prev) {
+		if ((tot_unique <= tot_unique_prev) && (tot_unique_edges <= tot_unique_edges_prev)) {
 			/* Finish searching for unique values when 1 loop dosnt give a
 			 * higher number of unique values compared to the previous loop */
 			break;
 		}
 		else {
 			tot_unique_prev = tot_unique;
+			tot_unique_edges_prev = tot_unique_edges;
 		}
 		/* Copy the hash calculated this iter, so we can use them next time */
 		memcpy(topo_hash_prev, topo_hash, sizeof(MirrTopoHash_t) * totvert);