# ROS–Unity Integration: Subscriber Create a simple Unity scene which subscribes to a [ROS topic](http://wiki.ros.org/ROS/Tutorials/UnderstandingTopics#ROS_Topics) to change the colour of a GameObject. **NOTE:** If following from [Publisher](publisher.md) tutorial proceed to [Setting Up Unity Scene](subscriber.md#setting-up-unity-scene) step. ## Setting Up ROS (You can skip this if you already did the [ROS–Unity Integration Publisher](publisher.md) tutorial.) - Copy the `tutorials/ros_packages/robotics_demo` folder of this repo into the `src` folder in your Catkin workspace. - Follow the [ROS–Unity Initial Setup](setup.md) guide. - Open a new terminal window, navigate to your Catkin workspace, and run the following commands: ```bash source devel/setup.bash rosrun robotics_demo server_endpoint.py ``` Once the server_endpoint has started, it will print something similar to `[INFO] [1603488341.950794]: Starting server on 192.168.50.149:10000`. ## Setting Up Unity Scene - Generate the C# code for `UnityColor` message by going to `RosMessageGeneration` -> `AutoGenerateMessages` -> `Single Message...` - Set the input file path to `PATH/TO/Unity-Robotics-Hub/tutorials/ros_packages/robotics_demo/msg/UnityColor.msg` and click `GENERATE!` - The generated file will be saved in the default directory `Assets/RosMessages/msg` - Create a script and name it `RosSubscriberExample.cs` - Paste the following code into `RosSubscriberExample.cs` - **Note** Script can be found at `tutorials/ros_unity_integration/unity_scripts` ```csharp using System.Net.Sockets; using System.Threading.Tasks; using UnityEngine; using RosColor = RosMessageTypes.RoboticsDemo.UnityColor; public class RosSubscriberExample : RosSubscriber { public GameObject cube; protected override async Task HandleConnectionAsync(TcpClient tcpClient) { await Task.Yield(); using (var networkStream = tcpClient.GetStream()) { RosColor colorMessage = (RosColor)ReadMessage(networkStream, new RosColor()); Debug.Log("Color(" + colorMessage.r + ", "+ colorMessage.g + ", "+ colorMessage.b + ", "+ colorMessage.a +")"); cube.GetComponent().material.color = new Color32((byte)colorMessage.r, (byte)colorMessage.g, (byte)colorMessage.b, (byte)colorMessage.a); } } void Start() { StartMessageServer(); } } ``` - Create an empty GameObject and name it `RosSubscriber` - Attach the `RosSubscriberExample` script to the `RosSubscriber` GameObject and drag the cube GameObject onto the `cube` parameter in the Inspector window. - In the Inspector window of the Editor change the `unityHostName` parameter on the `RosSubscriber ` GameObject to the Unity machine's URI. (Note for Windows users: the connection will be rejected unless you put the actual IP address ROS is connecting to. That's not necessarily the same as your machine's main IP address.) - Press play in the editor ### In ROS Terminal Window - After the scene has entered Play mode, run the following command: `rosrun robotics_demo color_publisher.py` to change the color of the cube GameObject in Unity to a random color ![](images/tcp_2.gif) Continue to the [ROS–Unity Integration Service](service.md).