diff --git a/topola-egui/src/displayer.rs b/topola-egui/src/displayer.rs
index bb1edf7..4a6f106 100644
--- a/topola-egui/src/displayer.rs
+++ b/topola-egui/src/displayer.rs
@@ -21,6 +21,7 @@ impl Displayer {
         workspace: &Workspace,
     ) {
         self.display_layout(ctx, ui, /*menu_bar,*/ viewport, workspace);
+        self.display_navmeshes(ctx, ui, viewport, workspace);
     }
 
     pub fn display_layout(
@@ -174,4 +175,59 @@ impl Displayer {
             egui::Stroke::new(5.0 / viewport.scale_factor(), color),
         ));
     }
+
+    fn display_navmeshes(
+        &mut self,
+        ctx: &egui::Context,
+        ui: &egui::Ui,
+        viewport: &Viewport,
+        workspace: &Workspace,
+    ) {
+        for layer in 0..*workspace.navmesher_board.board().layout().layer_count() {
+            if workspace.appearance_panel.visible[layer] {
+                for navmesh in workspace.navmesher_board.navmesher().layers()[layer].navmeshes() {
+                    for edge_geom in navmesh
+                        .triangulation()
+                        .rtreed_dcel()
+                        .edges_rtree()
+                        .as_ref()
+                        .iter()
+                    {
+                        let (from_vertex, to_vertex) = navmesh
+                            .triangulation()
+                            .rtreed_dcel()
+                            .dcel()
+                            .edge_endpoints(edge_geom.data);
+                        let from = navmesh
+                            .triangulation()
+                            .rtreed_dcel()
+                            .dcel()
+                            .vertex_weight(from_vertex)
+                            .position();
+                        let to = navmesh
+                            .triangulation()
+                            .rtreed_dcel()
+                            .dcel()
+                            .vertex_weight(to_vertex)
+                            .position();
+                        ui.painter().line_segment(
+                            [
+                                egui::pos2(*from.x() as f32, *from.y() as f32),
+                                egui::pos2(*to.x() as f32, *to.y() as f32),
+                            ],
+                            egui::Stroke::new(
+                                10.0,
+                                workspace
+                                    .appearance_panel
+                                    .colors(ctx)
+                                    .layers
+                                    .color(workspace.navmesher_board.board().layer_name(layer))
+                                    .normal,
+                            ),
+                        );
+                    }
+                }
+            }
+        }
+    }
 }
diff --git a/topola/src/board.rs b/topola/src/board.rs
index a31a986..ea3c104 100644
--- a/topola/src/board.rs
+++ b/topola/src/board.rs
@@ -7,8 +7,7 @@ use derive_getters::{Dissolve, Getters};
 use undoredo::{ApplyDelta, Delta, FlushDelta};
 
 use crate::layout::{
-    Arc, ArcId, Joint, JointId, Layout, LayoutHalfDelta, Polygon, PolygonId, Segment, SegmentId,
-    Via, ViaId,
+    Joint, JointId, Layout, LayoutHalfDelta, Polygon, PolygonId, Segment, SegmentId, Via, ViaId,
 };
 
 struct Layer {
diff --git a/topola/src/layout.rs b/topola/src/layout.rs
index 9a0b30b..230d294 100644
--- a/topola/src/layout.rs
+++ b/topola/src/layout.rs
@@ -56,31 +56,6 @@ pub struct Segment {
     pub half_width: u64,
 }
 
-#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
-pub struct ArcId(usize);
-
-impl ArcId {
-    /// Wrap an arc index in a newtype struct.
-    #[inline]
-    pub fn new(id: usize) -> Self {
-        Self(id)
-    }
-
-    /// Returns the underlying index.
-    #[inline]
-    pub fn id(self) -> usize {
-        self.0
-    }
-}
-
-#[derive(Clone, Copy, Debug)]
-pub struct Arc {
-    pub endpoints: [JointId; 2],
-    pub focus: [i64; 2],
-    pub layer: usize,
-    pub half_width: u64,
-}
-
 #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
 pub struct ViaId(usize);
 
diff --git a/topola/src/navmesher.rs b/topola/src/navmesher.rs
index d181e18..2b6a55a 100644
--- a/topola/src/navmesher.rs
+++ b/topola/src/navmesher.rs
@@ -7,7 +7,7 @@ use derive_getters::Getters;
 
 use crate::{
     Board,
-    layout::{Arc, ArcId, Joint, JointId, Polygon, PolygonId, Segment, SegmentId, Via, ViaId},
+    layout::{Joint, JointId, Polygon, PolygonId, Segment, SegmentId, Via, ViaId},
 };
 
 #[derive(Clone, Debug, Getters)]
@@ -19,8 +19,8 @@ pub struct LayerNavmesher {
 impl LayerNavmesher {
     pub fn new() -> Self {
         Self {
-            navmeshes: Vec::new(),
-            inflation_factors: Vec::new(),
+            navmeshes: vec![RecordingTriangulator::new()],
+            inflation_factors: vec![0.0],
         }
     }
 
@@ -28,7 +28,7 @@ impl LayerNavmesher {
         let polygon: Vec<[i64; 2]> = polygon.into_iter().collect();
 
         for i in 0..self.navmeshes.len() {
-            self.navmeshes[i].insert_polygon(Self::inflate_polygon(
+            self.navmeshes[i].insert_polygon_and_rebuild(Self::inflate_polygon(
                 polygon.clone(),
                 self.inflation_factors[i],
             ));
@@ -118,23 +118,34 @@ impl NavmesherBoard {
         let cy = joint.position[1];
         let r = joint.radius as i64;
 
+        [
+            [cx + r, cy + r / 2],
+            [cx + r / 2, cy + r],
+            [cx - r / 2, cy + r],
+            [cx - r, cy + r / 2],
+            [cx - r, cy - r / 2],
+            [cx - r / 2, cy - r],
+            [cx + r / 2, cy - r],
+            [cx + r, cy - r / 2],
+        ]
+
         // 1.082392... = 1 / cos(π/8)
         // 0.414213... = tan(π/8)
 
         // Approximate multipliers as fractions.
-        let r1 = (r * 277 + 128) / 256; // round(r * 1.0823922)
+        /*let r1 = (r * 277 + 128) / 256; // round(r * 1.0823922)
         let r2 = (r * 106 + 128) / 256; // round(r * 0.41421356)
 
         [
-            [cx + r1, cy],      // right
-            [cx + r2, cy + r2], // top-right
-            [cx, cy + r1],      // top
-            [cx - r2, cy + r2], // top-left
-            [cx - r1, cy],      // left
-            [cx - r2, cy - r2], // bottom-left
-            [cx, cy - r1],      // bottom
-            [cx + r2, cy - r2], // bottom-right
-        ]
+            [cx + r1, cy],
+            [cx + r2, cy + r2],
+            [cx, cy + r1],
+            [cx - r2, cy + r2],
+            [cx - r1, cy],
+            [cx - r2, cy - r2],
+            [cx, cy - r1],
+            [cx + r2, cy - r2],
+        ]*/
     }
 
     pub fn insert_segment(&mut self, segment: Segment) -> SegmentId {