diff --git a/examples/test_serialisation.rs b/examples/test_serialisation.rs
new file mode 100644
index 0000000..ca0e220
--- /dev/null
+++ b/examples/test_serialisation.rs
@@ -0,0 +1,31 @@
+use serde_json::Result;
+use trap_rust::trap::tracks::RenderableLines;
+
+/*
+Compare output with the following python
+```python
+import numpy as np
+import cv2
+
+H =np.array([[ 2.47442963e+02, -7.01714050e+01, -9.71749119e+01],
+            [ 1.02328119e+01,  1.47185254e+02,  1.96295638e+02],
+            [-1.20921986e-03, -3.32735973e-02,  1.00000000e+00]])
+
+points =[[1.,1.0],[2.0,2.0]]
+print(cv2.perspectiveTransform(np.array([points]), H))
+```
+ */
+fn main(){
+    let jsonstring = "{\"lines\": [{\"points\": [{\"position\": [ 1.008936882019043, 7.654696464538574], \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0250474214553833, \"y\": 7.690868854522705}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0388848781585693, \"y\": 7.721379280090332}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0500627756118774, \"y\": 7.7452192306518555}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.058650016784668, \"y\": 7.762533187866211}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0649632215499878, \"y\": 7.774103164672852}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.069427251815796, \"y\": 7.780993461608887}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0724823474884033, \"y\": 7.7843122482299805}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.074531078338623, \"y\": 7.785078525543213}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0759128332138062, \"y\": 7.784152030944824}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0768933296203613, \"y\": 7.782205581665039}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.07766854763031, \"y\": 7.779738426208496}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0783727169036865, \"y\": 7.777091026306152}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0790910720825195, \"y\": 7.774479866027832}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.079870581626892, \"y\": 7.772024631500244}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.080731749534607, \"y\": 7.769777774810791}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0816771984100342, \"y\": 7.767746925354004}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0826985836029053, \"y\": 7.765912055969238}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0837825536727905, \"y\": 7.764240741729736}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0849148035049438, \"y\": 7.762696743011475}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0860803127288818, \"y\": 7.76124382019043}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0872671604156494, \"y\": 7.759851455688477}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0884658098220825, \"y\": 7.758495807647705}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0896704196929932, \"y\": 7.757160186767578}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0908781290054321, \"y\": 7.755831718444824}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0920900106430054, \"y\": 7.754508018493652}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.093311071395874, \"y\": 7.7531890869140625}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0945500135421753, \"y\": 7.751882553100586}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0958201885223389, \"y\": 7.750600337982178}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0971378087997437, \"y\": 7.749356269836426}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0985240936279297, \"y\": 7.748173236846924}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0999997854232788, \"y\": 7.7470703125}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1015851497650146, \"y\": 7.746068477630615}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1032946109771729, \"y\": 7.74518346786499}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.105128526687622, \"y\": 7.744417190551758}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.107064127922058, \"y\": 7.743751049041748}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1090428829193115, \"y\": 7.743133544921875}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1109544038772583, \"y\": 7.742464065551758}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1126197576522827, \"y\": 7.741580009460449}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1137734651565552, \"y\": 7.740234375}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1140486001968384, \"y\": 7.738085746765137}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1129714250564575, \"y\": 7.734691143035889}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1099693775177002, \"y\": 7.729508399963379}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.1044032573699951, \"y\": 7.721929550170898}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0956374406814575, \"y\": 7.711339950561523}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0831615924835205, \"y\": 7.697234153747559}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0667784214019775, \"y\": 7.679385185241699}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.0468770265579224, \"y\": 7.65809965133667}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}, {\"position\": {\"x\": 1.027421236038208, \"y\": 7.636694431304932}, \"color\": {\"r\": 1.0, \"g\": 0.0, \"b\": 0.0, \"a\": 1.0}}]}]}";
+
+    let res: Result<RenderableLines> = serde_json::from_str(&jsonstring);
+
+    match res {
+        Ok(lines) => println!("{:?}", lines), // if Ok(255), set x to 255
+        Err(_e) => {
+            println!("No valid json?");
+            println!("{}", _e);
+        }, // if Err("some message"), panic with error message "some message"
+    };
+}   
+
diff --git a/src/main.rs b/src/main.rs
index de014f9..ddf0f10 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,8 +43,8 @@ fn main() {
 
         .add_plugins(ZmqPlugin { 
             // url: "tcp://localhost:5558".to_string(),
-            // url: "tcp://100.109.175.82:99173".to_string(),
-            url: "tcp://127.0.0.1:99173".to_string(),
+            url: "tcp://100.109.175.82:99174".to_string(),
+            // url: "tcp://127.0.0.1:99173".to_string(),
             filter: "".to_string(),
             target: ZmqReceiveTarget::LINES
         })
diff --git a/src/trap/tracks.rs b/src/trap/tracks.rs
index 5fb6780..b209424 100644
--- a/src/trap/tracks.rs
+++ b/src/trap/tracks.rs
@@ -40,18 +40,18 @@ pub struct Track {
 }
 
 // coordinates in world space. To be converted to laser::Point or a drawable point
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct RenderablePoint{
     pub position: Vec2,
-    pub color: Color
+    pub color: Srgba
 }
 
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct RenderableLine{
     points: Vec<RenderablePoint>
 }
 
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct RenderableLines{
     pub lines: Vec<RenderableLine>
 }
@@ -88,7 +88,7 @@ impl From<&Track> for RenderableLines{
             for position in track.history.iter() {
                 points.push(RenderablePoint{
                     position: position.clone(),
-                    color: Color::linear_rgba(1.0, 0., 0., 1.0)
+                    color: Srgba::new(1.0, 0., 0., 1.0)
                 });
             }
             lines.push(RenderableLine{points})
diff --git a/src/trap/zmqplugin.rs b/src/trap/zmqplugin.rs
index 54ad2d3..ab3a88c 100644
--- a/src/trap/zmqplugin.rs
+++ b/src/trap/zmqplugin.rs
@@ -1,7 +1,7 @@
 use zmq::Socket;
 use serde_json::Result;
 use bevy::{ecs::system::SystemState, prelude::*, render::Render};
-
+use std::num::NonZero;
 use super::{laser::{LaserApi, LaserTimer}, tracks::{Frame, LaserPoints, RenderableLines, Track, TrackBundle}};
 
 
@@ -46,7 +46,8 @@ fn setup_zmq(world: &mut World, params: &mut SystemState<Res<ZmqSettings>>) {
 fn receive_zmq_lines(
     subscriber: NonSend<Socket>,
     mut lasers: Query<(&mut LaserApi, &mut LaserTimer)>,
-    time: Res<Time>
+    time: Res<Time>,
+    mut exit: EventWriter<AppExit>
     ) {
     let mut items = [
         subscriber.as_poll_item(zmq::POLLIN)
@@ -64,9 +65,14 @@ fn receive_zmq_lines(
             Ok(lines) => lines, // if Ok(255), set x to 255
             Err(_e) => {
                 println!("No valid json? {json}");
+                println!("{}", _e);
+
+                exit.send(AppExit::Error(NonZero::<u8>::new(10).unwrap()));
                 return
             }, // if Err("some message"), panic with error message "some message"
         };
+
+        println!("receive {}", lines.lines.len());
         
         for (laser_api, mut laser_timer) in lasers.iter_mut() {
             laser_timer.timer.tick(time.delta());
@@ -80,7 +86,7 @@ fn receive_zmq_lines(
     }
 }
 
-fn receive_zmq_tracks(mut commands: Commands, subscriber: NonSend<Socket>, mut tracks_q: Query<&mut Track>) {
+fn receive_zmq_tracks(mut commands: Commands, subscriber: NonSend<Socket>, mut tracks_q: Query<&mut Track>, mut exit: EventWriter<AppExit>) {
     let mut items = [
         subscriber.as_poll_item(zmq::POLLIN)
     ];
@@ -97,6 +103,7 @@ fn receive_zmq_tracks(mut commands: Commands, subscriber: NonSend<Socket>, mut t
             Ok(msg) => msg, // if Ok(255), set x to 255
             Err(_e) => {
                 println!("No valid json? {json}");
+                exit.send(AppExit::Error(NonZero::<u8>::new(10).unwrap()));
                 return
             }, // if Err("some message"), panic with error message "some message"
         };