tweak to edge slide - use a quads opposite vertex when both edges share a quad, gives nicer results.

1 files changed, 11 insertions, 5 deletions

diff --git a/source/blender/editors/transform/transform.c b/source/blender/editors/transform/transform.c
index 6d11eebe7dc..e660a43767a 100644
--- a/source/blender/editors/transform/transform.c
+++ b/source/blender/editors/transform/transform.c
@@ -4917,10 +4917,19 @@ static BMLoop *get_next_loop(BMVert *v, BMLoop *l,
 				len_v3_ensure(vec_accum, vec_accum_len / (float)i);
 			}
 			else {
+				/* When there is no edge to slide along,
+				 * we must slide along the vector defined by the face we're attach to */
 				BMLoop *l_tmp = BM_face_vert_share_loop(l_first->f, v);
+				float tvec[3];
 
-				if (ELEM(l_tmp->e, e_prev, e_next) && ELEM(l_tmp->prev->e, e_prev, e_next)) {
-					float tvec[3];
+				BLI_assert(ELEM(l_tmp->e, e_prev, e_next) && ELEM(l_tmp->prev->e, e_prev, e_next));
+
+				if (l_tmp->f->len == 4) {
+					/* we could use code below, but in this case
+					 * sliding diagonally across the quad works well */
+					sub_v3_v3v3(vec_accum, l_tmp->next->next->v->co, v->co);
+				}
+				else {
 					BM_loop_calc_face_tangent(l_tmp, vec_accum);
 					if (!BM_loop_is_convex(l_tmp)) {
 						negate_v3(vec_accum);
@@ -4929,9 +4938,6 @@ static BMLoop *get_next_loop(BMVert *v, BMLoop *l,
 					cross_v3_v3v3(vec_accum, l_tmp->f->no, tvec);
 					len_v3_ensure(vec_accum, (BM_edge_calc_length(e_prev) + BM_edge_calc_length(e_next)) / 2.0f);
 				}
-				else {
-					BLI_assert(0);
-				}
 			}
 
 			copy_v3_v3(r_slide_vec, vec_accum);