diff --git a/src/autorouter/autoroute.rs b/src/autorouter/autoroute.rs
index fc231c1..81a4f92 100644
--- a/src/autorouter/autoroute.rs
+++ b/src/autorouter/autoroute.rs
@@ -2,12 +2,13 @@ use petgraph::graph::EdgeIndex;
 
 use crate::{
     board::mesadata::AccessMesadata,
+    drawing::graph::PrimitiveIndex,
     geometry::primitive::PrimitiveShape,
     router::{navmesh::Navmesh, route::Route, trace::Trace, Router, RouterStatus},
 };
 
 use super::{
-    invoker::{GetGhosts, GetMaybeNavmesh, GetMaybeTrace},
+    invoker::{GetGhosts, GetMaybeNavmesh, GetMaybeTrace, GetObstacles},
     Autorouter, AutorouterError, AutorouterStatus,
 };
 
@@ -104,3 +105,9 @@ impl GetGhosts for Autoroute {
         self.route.as_ref().map_or(&[], |route| route.ghosts())
     }
 }
+
+impl GetObstacles for Autoroute {
+    fn obstacles(&self) -> &[PrimitiveIndex] {
+        self.route.as_ref().map_or(&[], |route| route.obstacles())
+    }
+}
diff --git a/src/autorouter/invoker.rs b/src/autorouter/invoker.rs
index 67d5adf..8d42e69 100644
--- a/src/autorouter/invoker.rs
+++ b/src/autorouter/invoker.rs
@@ -33,6 +33,11 @@ pub trait GetGhosts {
     fn ghosts(&self) -> &[PrimitiveShape];
 }
 
+#[enum_dispatch]
+pub trait GetObstacles {
+    fn obstacles(&self) -> &[PrimitiveIndex];
+}
+
 #[derive(Error, Debug, Clone)]
 pub enum InvokerError {
     #[error(transparent)]
@@ -53,7 +58,7 @@ pub enum Command {
     PlaceVia(ViaWeight),
 }
 
-#[enum_dispatch(GetMaybeNavmesh, GetMaybeTrace, GetGhosts)]
+#[enum_dispatch(GetMaybeNavmesh, GetMaybeTrace, GetGhosts, GetObstacles)]
 pub enum Execute {
     Autoroute(Autoroute),
     PlaceVia(PlaceVia),
@@ -142,6 +147,12 @@ impl GetGhosts for ExecuteWithStatus {
     }
 }
 
+impl GetObstacles for ExecuteWithStatus {
+    fn obstacles(&self) -> &[PrimitiveIndex] {
+        self.execute.obstacles()
+    }
+}
+
 pub struct Invoker<M: AccessMesadata> {
     autorouter: Autorouter<M>,
     history: History,
diff --git a/src/autorouter/place_via.rs b/src/autorouter/place_via.rs
index ed151ec..f0cf97a 100644
--- a/src/autorouter/place_via.rs
+++ b/src/autorouter/place_via.rs
@@ -7,7 +7,7 @@ use crate::{
 };
 
 use super::{
-    invoker::{GetGhosts, GetMaybeNavmesh, GetMaybeTrace},
+    invoker::{GetGhosts, GetMaybeNavmesh, GetMaybeTrace, GetObstacles},
     Autorouter, AutorouterError,
 };
 
@@ -46,3 +46,9 @@ impl GetGhosts for PlaceVia {
         &[]
     }
 }
+
+impl GetObstacles for PlaceVia {
+    fn obstacles(&self) -> &[PrimitiveIndex] {
+        &[]
+    }
+}
diff --git a/src/bin/topola-egui/viewport.rs b/src/bin/topola-egui/viewport.rs
index 8022688..9ecba75 100644
--- a/src/bin/topola-egui/viewport.rs
+++ b/src/bin/topola-egui/viewport.rs
@@ -5,7 +5,8 @@ use petgraph::{
 };
 use topola::{
     autorouter::invoker::{
-        Command, ExecuteWithStatus, GetGhosts, GetMaybeNavmesh, GetMaybeTrace, Invoker,
+        Command, ExecuteWithStatus, GetGhosts, GetMaybeNavmesh, GetMaybeTrace, GetObstacles,
+        Invoker,
     },
     board::mesadata::AccessMesadata,
     drawing::{
@@ -111,7 +112,15 @@ impl Viewport {
                                         {
                                             layers.highlight_colors[i]
                                         } else {
-                                            layers.colors[i]
+                                            if let Some(execute) = maybe_execute {
+                                                if execute.obstacles().contains(&primitive) {
+                                                    layers.highlight_colors[i]
+                                                } else {
+                                                    layers.colors[i]
+                                                }
+                                            } else {
+                                                layers.colors[i]
+                                            }
                                         };
 
                                         painter.paint_primitive(&shape, color);
diff --git a/src/router/route.rs b/src/router/route.rs
index 982d2a4..6e5da73 100644
--- a/src/router/route.rs
+++ b/src/router/route.rs
@@ -37,6 +37,7 @@ pub struct Route {
     astar: Astar<Navmesh, f64>,
     trace: Trace,
     ghosts: Vec<PrimitiveShape>,
+    obstacles: Vec<PrimitiveIndex>,
 }
 
 impl Route {
@@ -65,11 +66,13 @@ impl Route {
         let mut strategy = RouterAstarStrategy::new(tracer, &mut trace, target);
         let astar = Astar::new(navmesh, source_navvertex, &mut strategy);
         let ghosts = vec![];
+        let obstacles = vec![];
 
         Self {
             astar,
             trace,
             ghosts,
+            obstacles,
         }
     }
 
@@ -86,7 +89,8 @@ impl Route {
             AstarStatus::Finished(_cost, _path, band) => Ok(RouterStatus::Finished(band)),
         };
 
-        self.ghosts = strategy.ghosts;
+        self.ghosts = strategy.last_ghosts;
+        self.obstacles = strategy.last_obstacles;
         result
     }
 
@@ -101,4 +105,8 @@ impl Route {
     pub fn ghosts(&self) -> &[PrimitiveShape] {
         &self.ghosts
     }
+
+    pub fn obstacles(&self) -> &[PrimitiveIndex] {
+        &self.obstacles
+    }
 }
diff --git a/src/router/router.rs b/src/router/router.rs
index 298ddfe..df34897 100644
--- a/src/router/router.rs
+++ b/src/router/router.rs
@@ -47,7 +47,8 @@ pub struct RouterAstarStrategy<'a, R: AccessRules> {
     pub tracer: Tracer<'a, R>,
     pub trace: &'a mut Trace,
     pub target: FixedDotIndex,
-    pub ghosts: Vec<PrimitiveShape>,
+    pub last_ghosts: Vec<PrimitiveShape>,
+    pub last_obstacles: Vec<PrimitiveIndex>,
 }
 
 impl<'a, R: AccessRules> RouterAstarStrategy<'a, R> {
@@ -56,7 +57,8 @@ impl<'a, R: AccessRules> RouterAstarStrategy<'a, R> {
             tracer,
             trace,
             target,
-            ghosts: vec![],
+            last_ghosts: vec![],
+            last_obstacles: vec![],
         }
     }
 
@@ -124,7 +126,7 @@ impl<'a, R: AccessRules> AstarStrategy<Navmesh, f64, BandFirstSegIndex>
                         DrawException::CannotWrapAround(.., layout_err) => layout_err,
                     };
 
-                    let (ghost, ..) = match layout_err {
+                    let (ghost, obstacle) = match layout_err {
                         LayoutException::NoTangents(..) => return None,
                         LayoutException::Infringement(Infringement(ghost, obstacle)) => {
                             (ghost, obstacle)
@@ -133,7 +135,8 @@ impl<'a, R: AccessRules> AstarStrategy<Navmesh, f64, BandFirstSegIndex>
                         LayoutException::AlreadyConnected(..) => return None,
                     };
 
-                    self.ghosts = vec![ghost];
+                    self.last_ghosts = vec![ghost];
+                    self.last_obstacles = vec![obstacle];
                 }
                 None
             }