# Unity

Software written with the Unity Engine can publish a stream to the server by acting as a [WebRTC client](05-webrtc-clients.md).

Create a new Unity project or open an existing one.

Open _Window -> Package Manager_, click on the plus sign, _Add Package by name..._ and insert `com.unity.webrtc`. Wait for the package to be installed.

In the _Project_ window, under `Assets`, create a new C# Script called `WebRTCPublisher.cs` with this content:

```cs
using System.Collections;
using UnityEngine;
using Unity.WebRTC;
using UnityEngine.Networking;

public class WebRTCPublisher : MonoBehaviour
{
    public string url = "http://localhost:8889/unity/whip";
    public int videoWidth = 1280;
    public int videoHeight = 720;

    private RTCPeerConnection pc;
    private MediaStream videoStream;

    void Start()
    {
        pc = new RTCPeerConnection();
        Camera sourceCamera = gameObject.GetComponent<Camera>();
        videoStream = sourceCamera.CaptureStream(videoWidth, videoHeight);
        foreach (var track in videoStream.GetTracks())
        {
            pc.AddTrack(track);
        }

        StartCoroutine(WebRTC.Update());
        StartCoroutine(createOffer());
    }

    private IEnumerator createOffer()
    {
        var op = pc.CreateOffer();
        yield return op;
        if (op.IsError) {
            Debug.LogError("CreateOffer() failed");
            yield break;
        }

        yield return setLocalDescription(op.Desc);
    }

    private IEnumerator setLocalDescription(RTCSessionDescription offer)
    {
        var op = pc.SetLocalDescription(ref offer);
        yield return op;
        if (op.IsError) {
            Debug.LogError("SetLocalDescription() failed");
            yield break;
        }

        yield return postOffer(offer);
    }

    private IEnumerator postOffer(RTCSessionDescription offer)
    {
        var content = new System.Net.Http.StringContent(offer.sdp);
        content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/sdp");
        var client = new System.Net.Http.HttpClient();

        var task = System.Threading.Tasks.Task.Run(async () => {
            var res = await client.PostAsync(new System.UriBuilder(url).Uri, content);
            res.EnsureSuccessStatusCode();
            return await res.Content.ReadAsStringAsync();
        });
        yield return new WaitUntil(() => task.IsCompleted);
        if (task.Exception != null) {
            Debug.LogError(task.Exception);
            yield break;
        }

        yield return setRemoteDescription(task.Result);
    }

    private IEnumerator setRemoteDescription(string answer)
    {
        RTCSessionDescription desc = new RTCSessionDescription();
        desc.type = RTCSdpType.Answer;
        desc.sdp = answer;
        var op = pc.SetRemoteDescription(ref desc);
        yield return op;
        if (op.IsError) {
            Debug.LogError("SetRemoteDescription() failed");
            yield break;
        }

        yield break;
    }

    void OnDestroy()
    {
        pc?.Close();
        pc?.Dispose();
        videoStream?.Dispose();
    }
}
```

In the _Hierarchy_ window, find or create a scene and a camera, then add the `WebRTCPublisher.cs` script as component of the camera, by dragging it inside the _Inspector_ window. then Press the _Play_ button at the top of the page.

The resulting stream will be available on path `/unity`.