Fix T75588: Missing loop cuts preview for edges without quads

The preview of points was only done when the edge is wire.

Now the preview of points is done when the edge is not connected to any
quad.

Also to avoid edge slide in this case, all new vertices created in this
specific case are not selected.

Differential Revision: https://developer.blender.org/D7457

2 files changed, 7 insertions, 5 deletions

diff --git a/source/blender/editors/mesh/editmesh_loopcut.c b/source/blender/editors/mesh/editmesh_loopcut.c
index 2f453369d92..b57e486634f 100644
--- a/source/blender/editors/mesh/editmesh_loopcut.c
+++ b/source/blender/editors/mesh/editmesh_loopcut.c
@@ -174,8 +174,10 @@ static void ringsel_finish(bContext *C, wmOperator *op)
     if (lcd->do_cut) {
       const bool is_macro = (op->opm != NULL);
       /* a single edge (rare, but better support) */
-      const bool is_single = (BM_edge_is_wire(lcd->eed));
-      const int seltype = is_single ? SUBDIV_SELECT_INNER : SUBDIV_SELECT_LOOPCUT;
+      const bool is_edge_wire = BM_edge_is_wire(lcd->eed);
+      const bool is_single = is_edge_wire || !BM_edge_is_any_face_len_test(lcd->eed, 4);
+      const int seltype = is_edge_wire ? SUBDIV_SELECT_INNER :
+                                         is_single ? SUBDIV_SELECT_NONE : SUBDIV_SELECT_LOOPCUT;
 
       /* Enable gridfill, so that intersecting loopcut works as one would expect.
        * Note though that it will break edgeslide in this specific case.
diff --git a/source/blender/editors/mesh/editmesh_preselect_edgering.c b/source/blender/editors/mesh/editmesh_preselect_edgering.c
index 50af79fc5e1..d9bd63ef35f 100644
--- a/source/blender/editors/mesh/editmesh_preselect_edgering.c
+++ b/source/blender/editors/mesh/editmesh_preselect_edgering.c
@@ -343,12 +343,12 @@ void EDBM_preselect_edgering_update_from_edge(struct EditMesh_PreSelEdgeRing *ps
     BM_mesh_elem_index_ensure(bm, BM_VERT);
   }
 
-  if (BM_edge_is_wire(eed_start)) {
-    view3d_preselect_mesh_edgering_update_verts_from_edge(
+  if (BM_edge_is_any_face_len_test(eed_start, 4)) {
+    view3d_preselect_mesh_edgering_update_edges_from_edge(
         psel, bm, eed_start, previewlines, coords);
   }
   else {
-    view3d_preselect_mesh_edgering_update_edges_from_edge(
+    view3d_preselect_mesh_edgering_update_verts_from_edge(
         psel, bm, eed_start, previewlines, coords);
   }
 }