diff --git a/src/mesh.rs b/src/mesh.rs
index 8d578ea..b43f54c 100644
--- a/src/mesh.rs
+++ b/src/mesh.rs
@@ -35,7 +35,7 @@ impl Mesh {
 
     pub fn add_seg(&mut self, from: DotIndex, to: DotIndex, weight: SegWeight) -> SegIndex {
         let seg = SegIndex::new(self.graph.add_node(TaggedWeight::Seg(weight)));
-        self.graph.add_edge(seg.index, from.index, Label::End);
+        self.graph.add_edge(from.index, seg.index, Label::End);
         self.graph.add_edge(seg.index, to.index, Label::End);
 
         self.rtree.insert(RTreeWrapper::new(self.primitive(seg).shape(), TaggedIndex::Seg(seg)));
@@ -59,7 +59,7 @@ impl Mesh {
 
     pub fn add_core_bend(&mut self, from: DotIndex, to: DotIndex, core: DotIndex, weight: BendWeight) -> BendIndex {
         let bend = BendIndex::new(self.graph.add_node(TaggedWeight::Bend(weight)));
-        self.graph.add_edge(bend.index, from.index, Label::End);
+        self.graph.add_edge(from.index, bend.index, Label::End);
         self.graph.add_edge(bend.index, to.index, Label::End);
         self.graph.add_edge(bend.index, core.index, Label::Core);
 
diff --git a/src/primitive.rs b/src/primitive.rs
index 8f21d6a..68ca38f 100644
--- a/src/primitive.rs
+++ b/src/primitive.rs
@@ -49,9 +49,23 @@ impl<'a, Weight> Primitive<'a, Weight> {
         }
     }
 
-    pub fn ends(&self) -> Vec<DotIndex> {
-        self.graph.neighbors(self.index.index)
+    pub fn next(&self) -> Option<TaggedIndex> {
+        self.graph.neighbors_directed(self.index.index, Outgoing)
+            .filter(|ni| self.graph.edge_weight(self.graph.find_edge(*ni, self.index.index).unwrap()).unwrap().is_end())
+            .map(|ni| Index::<Label>::new(ni).retag(*self.graph.node_weight(ni).unwrap()))
+            .next()
+    }
+
+    pub fn prev(&self) -> Option<TaggedIndex> {
+        self.graph.neighbors_directed(self.index.index, Incoming)
             .filter(|ni| self.graph.edge_weight(self.graph.find_edge(self.index.index, *ni).unwrap()).unwrap().is_end())
+            .map(|ni| Index::<Label>::new(ni).retag(*self.graph.node_weight(ni).unwrap()))
+            .next()
+    }
+
+    pub fn ends(&self) -> Vec<DotIndex> {
+        self.graph.neighbors_undirected(self.index.index)
+            .filter(|ni| self.graph.edge_weight(self.graph.find_edge_undirected(self.index.index, *ni).unwrap().0).unwrap().is_end())
             .filter(|ni| self.graph.node_weight(*ni).unwrap().is_dot())
             .map(|ni| DotIndex::new(ni))
             .collect()