fix [#31197] Limited dissolve leaves faces/edges/verts behind

bad bug where vertices could be in a face more then once (which isn't allowed), now check for this when creating a face.

2 files changed, 14 insertions, 0 deletions

diff --git a/source/blender/bmesh/intern/bmesh_construct.c b/source/blender/bmesh/intern/bmesh_construct.c
index 0169caa8f61..684237b79c5 100644
--- a/source/blender/bmesh/intern/bmesh_construct.c
+++ b/source/blender/bmesh/intern/bmesh_construct.c
@@ -214,6 +214,9 @@ BMFace *BM_face_create_ngon(BMesh *bm, BMVert *v1, BMVert *v2, BMEdge **edges, i
 		BLI_array_append(verts, v);
 		BLI_array_append(edges2, e);
 
+		/* we only flag the verts to check if they are in the face more then once */
+		BM_ELEM_API_FLAG_ENABLE(v, _FLAG_MV);
+
 		do {
 			e2 = bmesh_disk_edge_next(e2, v);
 			if (e2 != e && BM_ELEM_API_FLAG_TEST(e2, _FLAG_MF)) {
@@ -269,6 +272,12 @@ BMFace *BM_face_create_ngon(BMesh *bm, BMVert *v1, BMVert *v2, BMEdge **edges, i
 		if (!edges2[i]) {
 			goto err;
 		}
+
+		/* check if vert is in face more then once. if the flag is disabled. we've already visited */
+		if (!BM_ELEM_API_FLAG_TEST(verts[i], _FLAG_MV)) {
+			goto err;
+		}
+		BM_ELEM_API_FLAG_DISABLE(verts[i], _FLAG_MV);
 	}
 
 	f = BM_face_create(bm, verts, edges2, len, nodouble);
@@ -286,6 +295,10 @@ BMFace *BM_face_create_ngon(BMesh *bm, BMVert *v1, BMVert *v2, BMEdge **edges, i
 err:
 	for (i = 0; i < len; i++) {
 		BM_ELEM_API_FLAG_DISABLE(edges[i], _FLAG_MF);
+		/* vert count may != len */
+		if (i < BLI_array_count(verts)) {
+			BM_ELEM_API_FLAG_DISABLE(verts[i], _FLAG_MV);
+		}
 	}
 
 	BLI_array_free(verts);
diff --git a/source/blender/bmesh/intern/bmesh_private.h b/source/blender/bmesh/intern/bmesh_private.h
index 23d0a1e3906..0827901f5c2 100644
--- a/source/blender/bmesh/intern/bmesh_private.h
+++ b/source/blender/bmesh/intern/bmesh_private.h
@@ -60,6 +60,7 @@ int bmesh_disk_count(BMVert *v);
  * on using these internal flags!*/
 #define _FLAG_JF	1 /* join faces */
 #define _FLAG_MF	2 /* make face */
+#define _FLAG_MV	2 /* make face, vertex */
 
 #define BM_ELEM_API_FLAG_ENABLE(element, f)  ((element)->oflags[0].pflag |=  (f))
 #define BM_ELEM_API_FLAG_DISABLE(element, f) ((element)->oflags[0].pflag &= ~(f))