fix [#34073] Combined EdgeLoop slides weirdly on even try

concave check on co-linear edges could fail, avoid by using the loop-direction + face normal.

2 files changed, 24 insertions, 0 deletions

diff --git a/source/blender/bmesh/intern/bmesh_queries.c b/source/blender/bmesh/intern/bmesh_queries.c
index bf30db78a61..b2b710a0d36 100644
--- a/source/blender/bmesh/intern/bmesh_queries.c
+++ b/source/blender/bmesh/intern/bmesh_queries.c
@@ -1058,6 +1058,29 @@ void BM_loop_calc_face_normal(BMLoop *l, float r_normal[3])
 }
 
 /**
+ * \brief BM_loop_calc_face_direction
+ *
+ * Calculate the direction a loop is pointing.
+ *
+ * \param l The loop to calculate the direction at
+ * \param r_dir Resulting direction
+ */
+void BM_loop_calc_face_direction(BMLoop *l, float r_dir[3])
+{
+	float v_prev[3];
+	float v_next[3];
+
+	sub_v3_v3v3(v_prev, l->v->co, l->prev->v->co);
+	sub_v3_v3v3(v_next, l->next->v->co, l->v->co);
+
+	normalize_v3(v_prev);
+	normalize_v3(v_next);
+
+	add_v3_v3v3(r_dir, v_prev, v_next);
+	normalize_v3(r_dir);
+}
+
+/**
  * \brief BM_loop_calc_face_tangent
  *
  * Calculate the tangent at this loop corner or fallback to the face normal on straight lines.
diff --git a/source/blender/bmesh/intern/bmesh_queries.h b/source/blender/bmesh/intern/bmesh_queries.h
index 4172b3905cd..b285c531bb5 100644
--- a/source/blender/bmesh/intern/bmesh_queries.h
+++ b/source/blender/bmesh/intern/bmesh_queries.h
@@ -66,6 +66,7 @@ bool    BM_loop_is_convex(BMLoop *l);
 
 float   BM_loop_calc_face_angle(BMLoop *l);
 void    BM_loop_calc_face_normal(BMLoop *l, float r_normal[3]);
+void    BM_loop_calc_face_direction(BMLoop *l, float r_normal[3]);
 void    BM_loop_calc_face_tangent(BMLoop *l, float r_tangent[3]);
 
 float   BM_edge_calc_face_angle(BMEdge *e);