Merge branch 'develop' into fix/replace-null-coalescence-operators

Author: LPLafontaineB

Packages/com.unity.multiplayer.samples.coop/CHANGELOG.md

@@ -6,6 +6,7 @@
 * Replaced usages of null-coalescing and null-conditional operators with regular null checks. (#867) These operators can cause issues when used with types inheriting UnityEngine.Object because that type redefines the == operator to define when an object is null. This redefinition applies to regular null checks (if foo == null) but not to those operators, thus this could lead to unexpected behaviour. While those operators were safely used within Boss Room, only with types that were not inheriting UnityEngine.Object, we decided to remove most usages for consistency. This will also help avoid accidental mistakes, such as a user reusing a part of this code, but modifying it so that one of those operators are used with a UnityEngine.Object.
 
 ### Fixed
+* Clarified fix used to handle clients reconnecting to the server while keeping the same active scene and having additional scenes additively loaded (#864)
 * Host loading progress bar is now properly updated on all clients during scene loads (#862)
 
 ## [1.6.1] - 2023-06-14

Packages/com.unity.multiplayer.samples.coop/Utilities/SceneManagement/SceneLoaderWrapper.cs

@@ -133,7 +133,7 @@ void OnSceneEvent(SceneEvent sceneEvent)
             switch (sceneEvent.SceneEventType)
             {
                 case SceneEventType.Load: // Server told client to load a scene
-                    // Only executes on client
+                    // Only executes on client or host
                     if (NetworkManager.IsClient)
                     {
                         // Only start a new loading screen if scene loaded in Single mode, else simply update
@@ -150,22 +150,29 @@ void OnSceneEvent(SceneEvent sceneEvent)
                     }
                     break;
                 case SceneEventType.LoadEventCompleted: // Server told client that all clients finished loading a scene
-                    // Only executes on client
+                    // Only executes on client or host
                     if (NetworkManager.IsClient)
                     {
                         m_ClientLoadingScreen.StopLoadingScreen();
                     }
                     break;
                 case SceneEventType.Synchronize: // Server told client to start synchronizing scenes
                 {
-                    // todo: this is a workaround that could be removed once MTT-3363 is done
                     // Only executes on client that is not the host
                     if (NetworkManager.IsClient && !NetworkManager.IsHost)
                     {
-                        // unload all currently loaded additive scenes so that if we connect to a server with the same
-                        // main scene we properly load and synchronize all appropriate scenes without loading a scene
-                        // that is already loaded.
-                        UnloadAdditiveScenes();
+                        if (NetworkManager.SceneManager.ClientSynchronizationMode == LoadSceneMode.Single)
+                        {
+                            // If using the Single ClientSynchronizationMode, unload all currently loaded additive
+                            // scenes. In this case, we want the client to only keep the same scenes loaded as the
+                            // server. Netcode For GameObjects will automatically handle loading all the scenes that the
+                            // server has loaded to the client during the synchronization process. If the server's main
+                            // scene is different to the client's, it will start by loading that scene in single mode,
+                            // unloading every additively loaded scene in the process. However, if the server's main
+                            // scene is the same as the client's, it will not automatically unload additive scenes, so
+                            // we do it manually here.
+                            UnloadAdditiveScenes();
+                        }
                     }
                     break;
                 }