Add a VR Broadcaster Component that only broadcasts to first connected client (#1)

* Add Broadcast Logic to accept only 1 connection

* Attach VR Broadcaster to Render Streaming

Tested with 2 Unity instances running and both client successfully connected to the respective instance using just one WebRTC server

Author: vmohan7

Runtime/Prefabs/Render Streaming Services.prefab

@@ -662,7 +662,7 @@ GameObject:
   m_Component:
   - component: {fileID: 1793859183747734309}
   - component: {fileID: 1793859183747734314}
-  - component: {fileID: 1793859183747734308}
+  - component: {fileID: 48972029}
   m_Layer: 0
   m_Name: RenderStreaming
   m_TagString: Untagged
@@ -707,9 +707,9 @@ MonoBehaviour:
   interval: 5
   hardwareEncoderSupport: 1
   handlers:
-  - {fileID: 1793859183747734308}
+  - {fileID: 48972029}
   runOnAwake: 1
---- !u!114 &1793859183747734308
+--- !u!114 &48972029
 MonoBehaviour:
   m_ObjectHideFlags: 0
   m_CorrespondingSourceObject: {fileID: 0}
@@ -718,7 +718,7 @@ MonoBehaviour:
   m_GameObject: {fileID: 1793859183747734311}
   m_Enabled: 1
   m_EditorHideFlags: 0
-  m_Script: {fileID: 11500000, guid: c2307e7ad91222841b562bebd81a69a0, type: 3}
+  m_Script: {fileID: 11500000, guid: 31b94e633688a294abc5410d3190b6f5, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
   streams:

Runtime/Scripts/VRBroadcast.cs

@@ -0,0 +1,97 @@
+/**
+ * Copyright 2021 Vasanth Mohan. All rights and licenses reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ */
+
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+using Unity.RenderStreaming;
+
+namespace FusedVR.VRStreaming {
+    /// <summary>
+    /// VRBroadcast is very similar to the Broadcast script included with Render Streaming.
+    /// This script is responsible for listening for offers from the client and choosing when to respond. 
+    /// </summary>
+    public class VRBroadcast : SignalingHandlerBase,
+        IOfferHandler, IAddChannelHandler, IDisconnectHandler, IDeletedConnectionHandler {
+
+        /// <summary>
+        /// Streams (video, audio, data) that need to be sent to the client
+        /// </summary>
+        [SerializeField]
+        private List<Component> streams = new List<Component>();
+
+        /// <summary>
+        /// List of all connectionIds that are connected
+        /// </summary>
+        private List<string> connectionIds = new List<string>();
+
+        #region Disconnect
+        public void OnDeletedConnection(SignalingEventData eventData) {
+            Disconnect(eventData.connectionId);
+        }
+
+        public void OnDisconnect(SignalingEventData eventData) {
+            Disconnect(eventData.connectionId);
+        }
+
+        private void Disconnect(string connectionId) {
+            if (!connectionIds.Contains(connectionId))
+                return;
+            connectionIds.Remove(connectionId);
+
+            foreach (var source in streams.OfType<IStreamSource>()) {
+                source.SetSender(connectionId, null);
+            }
+            foreach (var receiver in streams.OfType<IStreamReceiver>()) {
+                receiver.SetReceiver(connectionId, null);
+            }
+            foreach (var channel in streams.OfType<IDataChannel>()) {
+                channel.SetChannel(connectionId, null);
+            }
+        }
+        #endregion
+
+        /// <summary>
+        /// Event that is called when an Offer is made by a client
+        /// Determines whether to accept offer and if so that to apply sources and submit answer
+        /// </summary>
+        public void OnOffer(SignalingEventData data) {
+            if (connectionIds.Count >= 1) { //if there is more than 1 connection, let's skip this offer
+                Debug.Log($"Already answered this connectionId : {connectionIds[0]}");
+                return;
+            }
+
+            if (connectionIds.Contains(data.connectionId)) { //if connection is already connected, skip offer
+                Debug.Log($"Already answered this connectionId : {data.connectionId}");
+                return;
+            }
+            connectionIds.Add(data.connectionId); //confirm we will use this connection
+
+            foreach (var source in streams.OfType<IStreamSource>()) {
+                var transceiver = AddTrack(data.connectionId, source.Track);
+                source.SetSender(data.connectionId, transceiver.Sender);
+            }
+            foreach (var channel in streams.OfType<IDataChannel>().Where(c => c.IsLocal)) {
+                var _channel = CreateChannel(data.connectionId, channel.Label);
+                channel.SetChannel(data.connectionId, _channel);
+            }
+            SendAnswer(data.connectionId); //accept offer with an answer
+        }
+
+        /// <summary>
+        /// Apply Data Channel
+        /// </summary>
+        public void OnAddChannel(SignalingEventData data) {
+            var channel = streams.OfType<IDataChannel>().
+                FirstOrDefault(r => r.Channel == null && !r.IsLocal);
+            channel?.SetChannel(data.connectionId, data.channel);
+        }
+    }
+}