bmesh: improve rip tool

- When the rip extends into a fan, pick the opposite edge in the fan (rather then 2 along)
- When stepping over the fan to find the rip edge, walk in the direction closest to the mouse (generally works nicer) 

3 files changed, 55 insertions, 2 deletions

diff --git a/source/blender/bmesh/intern/bmesh_core.c b/source/blender/bmesh/intern/bmesh_core.c
index 76095728d5a..51ca11b0898 100644
--- a/source/blender/bmesh/intern/bmesh_core.c
+++ b/source/blender/bmesh/intern/bmesh_core.c
@@ -814,8 +814,7 @@ static int UNUSED_FUNCTION(count_flagged_disk)(BMVert *v, int flag)
 
 	do {
 		i += BM_ELEM_API_FLAG_TEST(e, flag) ? 1 : 0;
-		e = bmesh_disk_edge_next(e, v);
-	} while (e != v->e);
+	} while ((e = bmesh_disk_edge_next(e, v)) != v->e);
 
 	return i;
 }
diff --git a/source/blender/bmesh/intern/bmesh_queries.c b/source/blender/bmesh/intern/bmesh_queries.c
index 09cd6a2f96b..3561092b1cf 100644
--- a/source/blender/bmesh/intern/bmesh_queries.c
+++ b/source/blender/bmesh/intern/bmesh_queries.c
@@ -309,6 +309,59 @@ BMVert *BM_edge_other_vert(BMEdge *e, BMVert *v)
 }
 
 /**
+ * The function takes a vertex at the center of a fan and returns the opposite edge in the fan.
+ * All edges in the fan must be manifold, otherwise return NULL.
+ *
+ * \note This could (probably) be done more effieiently.
+ */
+BMEdge *BM_vert_other_disk_edge(BMVert *v, BMEdge *e_first)
+{
+	BMLoop *l_a;
+	int tot = 0;
+	int i;
+
+	BLI_assert(BM_vert_in_edge(e_first, v));
+
+	l_a = e_first->l;
+	do {
+		l_a = BM_loop_other_vert_loop(l_a, v);
+		l_a = BM_vert_in_edge(l_a->e, v) ? l_a : l_a->prev;
+		if (BM_edge_is_manifold(l_a->e)) {
+			l_a = l_a->radial_next;
+		}
+		else {
+			return NULL;
+		}
+
+		tot++;
+	} while (l_a != e_first->l);
+
+	/* we know the total, now loop half way */
+	tot /= 2;
+	i = 0;
+
+	l_a = e_first->l;
+	do {
+		if (i == tot) {
+			l_a = BM_vert_in_edge(l_a->e, v) ? l_a : l_a->prev;
+			return l_a->e;
+		}
+
+		l_a = BM_loop_other_vert_loop(l_a, v);
+		l_a = BM_vert_in_edge(l_a->e, v) ? l_a : l_a->prev;
+		if (BM_edge_is_manifold(l_a->e)) {
+			l_a = l_a->radial_next;
+		}
+		/* this wont have changed from the previous loop */
+
+
+		i++;
+	} while (l_a != e_first->l);
+
+	return NULL;
+}
+
+/**
  * Returms edge length
  */
 float BM_edge_length_calc(BMEdge *e)
diff --git a/source/blender/bmesh/intern/bmesh_queries.h b/source/blender/bmesh/intern/bmesh_queries.h
index d69a57bdb40..5178311eea4 100644
--- a/source/blender/bmesh/intern/bmesh_queries.h
+++ b/source/blender/bmesh/intern/bmesh_queries.h
@@ -49,6 +49,7 @@ int     BM_vert_edge_count_nonwire(BMVert *v);
 int     BM_vert_edge_count(BMVert *v);
 int     BM_edge_face_count(BMEdge *e);
 int     BM_vert_face_count(BMVert *v);
+BMEdge *BM_vert_other_disk_edge(BMVert *v, BMEdge *e);
 
 int     BM_vert_is_wire(BMVert *v);
 int     BM_edge_is_wire(BMEdge *e);