4 - Game Manager & Levels

This section covers the addition of features to handle the various loading of levels based on the number of players currently playing in the room.

Loading Arena Routine

We've created 4 different rooms, and we named them all with the convention that the last character is the number of players, so it's now very easy to bind the current number of players in the room and the related scene.
It's a very effective technique known as "convention over configuration". A "configuration" based approach would have been, for example, maintaining a lookup table list of the scene name for a given number of players in a room.
Our scripts would have then looked in that list and be returned a scene in which the name doesn't matter at all.
"configuration" requires more scripting in general, that's why we'll go for "convention" here which gets us to working code faster without polluting our code with unrelated features.

1. Open GameManager script

2. Let's add a new method within a new region dedicated to private methods we'll create for the occasion.
   Don't forget to save GameManager script.

   C#

   #region Private Methods
   
   void LoadArena()
   {
       if (!PhotonNetwork.IsMasterClient) 
       {
           Debug.LogError("PhotonNetwork : Trying to Load a level but we are not the master Client");
           return;
       }
       Debug.LogFormat("PhotonNetwork : Loading Level : {0}", PhotonNetwork.CurrentRoom.PlayerCount);
       PhotonNetwork.LoadLevel("Room for " + PhotonNetwork.CurrentRoom.PlayerCount);
   }
   
   #endregion
   

3. Save GameManager script

When we'll call this method, we are going to load the appropriate room, based on the PlayerCount property of the room we are in.

There are two things to watch out for here, it's very important.

• PhotonNetwork.LoadLevel() should only be called if we are the MasterClient. So we check first that we are the MasterClient using PhotonNetwork.IsMasterClient.
  It will be the responsibility of the caller to also check for this, we'll cover that in the next part of this section.
• We use PhotonNetwork.LoadLevel() to load the level we want, we don't use Unity directly, because we want to rely on Photon to load this level on all connected clients in the room, since we've enabled PhotonNetwork.AutomaticallySyncScene for this Game.

Now that we have our function to load the right level, let's bind this with players connecting and disconnecting.

Watching Players Connection

We've studied the various ways to get Photon Callbacks in previous part of the tutorial and now the GameManager needs to listen to players connecting and disconnecting.
Let's implement this.

1. Open GameManager script

2. Add the following Photon Callbacks and save GameManager script

   C#

   #region Photon Callbacks
   
   public override void OnPlayerEnteredRoom(Player other)
   {
       Debug.LogFormat("OnPlayerEnteredRoom() {0}", other.NickName); // not seen if you're the player connecting
   
       if (PhotonNetwork.IsMasterClient) 
       {
           Debug.LogFormat("OnPlayerEnteredRoom IsMasterClient {0}", PhotonNetwork.IsMasterClient); // called before OnPlayerLeftRoom
   
           LoadArena();
       }
   }
   
   public override void OnPlayerLeftRoom(Player other)
   {
       Debug.LogFormat("OnPlayerLeftRoom() {0}", other.NickName); // seen when other disconnects
   
       if (PhotonNetwork.IsMasterClient) 
       {
           Debug.LogFormat("OnPlayerLeftRoom IsMasterClient {0}", PhotonNetwork.IsMasterClient); // called before OnPlayerLeftRoom
   
           LoadArena();
       }
   }
   
   #endregion
   

3. Save GameManager script

Now, we have a complete setup. Every time a player joins or leaves the room, we'll be informed, and we'll call the LoadArena() method we've implemented before.
However, we'll call LoadArena() ONLY if we are the MasterClient using PhotonNetwork.IsMasterClient.

Let's now come back to the Lobby to finally be able to load the right scene when joining a room.

Loading Arena from the Lobby

1. Edit the Script Launcher.

2. Append the following to the OnJoinedRoom() method

   C#

   // #Critical: We only load if we are the first player, else we rely on `PhotonNetwork.AutomaticallySyncScene` to sync our instance scene.
   if (PhotonNetwork.CurrentRoom.PlayerCount == 1)
   {
       Debug.Log("We load the 'Room for 1' ");
   
       // #Critical
       // Load the Room Level. 
       PhotonNetwork.LoadLevel("Room for 1");
   }
   

3. Save the Script Launcher.

Let's test this, open the scene Launcher, and run it. Click on "Play", and let the system connect and join a room.
That's it, we now have our lobby working. But if you leave the room, you'll notice that when coming back to the lobby, it automatically rejoins... oops, let's address this.

If you don't know why this happens yet, "simply" analyze the logs. I put simply in quote, because it takes practice and experience to acquire the automatism to overview an issue and know where to look and how to debug it.

Try yourself now and if you are still unable to find the source of the problem, let's do this together.

1. Run the Launcher Scene
2. Hit the "Play" button, and wait until you've joined the room and that "Room for 1" is loaded
3. Clear the Unity Console
4. Hit "Leave Room"
5. Study the Unity Console, notice that "PUN Basics Tutorial/Launcher: OnConnectedToMaster() was called by PUN" is logged
6. Stop the Launcher Scene
7. Double Click on the log entry "PUN Basics Tutoria/Launcher: OnConnectedToMaster() was called by PUN" the script will be loaded and point to the line of the debug call.
8. Uhmmm... so, every time we get informed that we are connected, we automatically join a random room which is not what we want.

To fix this, we need to be aware of the context. When the User clicks on the "Play" button, we should raise a flag to be aware that the connection procedure originated from the user.
Then we can check for this flag to act accordingly within the various Photon Callbacks.

1. Edit the script Launcher

2. Create a new property within the Private Fields regions

   C#

       /// <summary>
       /// Keep track of the current process. Since connection is asynchronous and is based on several callbacks from Photon, 
       /// we need to keep track of this to properly adjust the behavior when we receive call back by Photon.
       /// Typically this is used for the OnConnectedToMaster() callback.
       /// </summary>
       bool isConnecting;
   

3. Inside Connect() method set isConnecting to the return value of the PhotonNetwork.ConnectUsingSettings() method as follows:

   C#

       // keep track of the will to join a room, because when we come back from the game we will get a callback that we are connected, so we need to know what to do then
       isConnecting = PhotonNetwork.ConnectUsingSettings();
   

   result:

   C#

       public void Connect()
       {
           progressLabel.SetActive(true);
           controlPanel.SetActive(false);
           if (PhotonNetwork.IsConnected)
           {
               PhotonNetwork.JoinRandomRoom();
           } 
           else 
           {
               isConnecting = PhotonNetwork.ConnectUsingSettings();
               PhotonNetwork.GameVersion = gameVersion;
           }
       }
   

4. in OnConnectedToMaster() method, surround the PhotonNetwork.JoinRandomRoom() with an if statement as follow

   C#

       // we don't want to do anything if we are not attempting to join a room. 
       // this case where isConnecting is false is typically when you lost or quit the game, when this level is loaded, OnConnectedToMaster will be called, in that case
       // we don't want to do anything.
       if (isConnecting)
       {
           // #Critical: The first we try to do is to join a potential existing room. If there is, good, else, we'll be called back with OnJoinRandomFailed()
           PhotonNetwork.JoinRandomRoom();
           isConnecting = false;
       }
   

5. in OnDisconnected method, set isConnecting to false

6. Save the script Launcher

Now if we test again and run the Launcher Scene, and go back and forth between the Lobby and the Game, all is well :)
In order to test the automatic syncing of scenes, you'll need to publish the application (publish for desktop, it's the quickest for running tests), and run it alongside Unity, so you have effectively two players that will connected and join a room.
If the Unity Editor creates the Room first, it will be the MasterClient and you'll be able to verify in the Unity Console that you get "PhotonNetwork : Loading Level : 1" and later "PhotonNetwork : Loading Level : 2" as you connect with the published instance.

Good! We have covered a lot, but this is only half of the job... :)
We need to tackle the Player himself, so let's do that in the next section.
Don't forget to take breaks away from the computer from time to time, to be more effective in absorbing the various concepts explained.

Don't hesitate to ask questions on the forum if you are in doubt of a particular feature or if you have trouble following this tutorial and hit an error or an issue that is not covered here, we'll be happy to help :)

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