Feedback needed! New Doc for Getting Started with Unity Multiplayer

Hi Erik,
I really appreciated this document. I gave a fast look at it, and the main idea looks great. Please go on!

 

Hi Erik,

While I worked all that out myself, I can see how much of a massive, massive time saver it would have been to have a digestible doc that just says how it is, so that would have helped me a great deal - certainly more helpful than trying to pick part demos which all have different styles and no real overview of explaining why decisions were made (fairly important to explain why given the number of multiple ways to skin this fish).

The doc needs work for formatting but I think you know that already. Please keep it up for tackling different areas of networking!

So I think it's a winner. More please!

 

EDIT: Note that this version is to be included for those developers who wanted to just "scan" or "give a glance" to find relevant information/references without needing to read the entire doc. Please understand.

Can you also add an ELI5 condensed version of the code (given below) to that doc, like an Appendix or, SSCCE version?

Code (CSharp):

1. using UnityEngine.Networking;
2.  
3. public class CustomScript : NetworkBehaviour {
4.     [ServerCallback]
5.     public void ServerStuff(GameObject newObject, Vector3 newObjectPosition){
6.         //Do server-side stuff. Initializing all game stuffs can be used here. Syncing objects can also be used here.
7.  
8.         //Let's pretend "newObject" has NetworkTransform attached.
9.         newObject.transform.position = newObjectPosition;
10.  
11.         //Now newObject's NetworkTransform will sync the new position across all connected clients. The values are updated on the server
12.         //side, all clients will have their old positions marked as Dirty() and will update to the server's values.
13.     }
14.  
15.     [ClientCallback]
16.     public void ClientStuff(){
17.         //Do client-side stuff.
18.  
19.         //Client may have this registered prefab from the Network Manager, but usually it's better to have it available in the Hierarchy before continuing. Usually, it's assigned directly through the Inspector, but let's go with this.
20.         GameObject prefabObject = GameObject.FindGameObjectWithTag("SamplePrefab");
21.         if (prefabObject != null){
22.             //Always check for null. In UNET, there may be times where the object is not spawned through NetworkServer, thus the object will be missing.
23.             CmdDoAction(prefabObject);
24.         }
25.     }
26.  
27.     [Command]
28.     public void CmdDoAction(GameObject objectToUse){
29.         //This is where you would do stuffs that the client wants the server to do.
30.         GameObject obj = Instantiate<GameObject>(objectToUse);
31.         NetworkServer.SpawnWithClientAuthority(obj, this.connectionToClient);
32.  
33.         //Or just have the server do something for the client.
34.         obj = Instantiate<GameObject>(objectToUse);
35.         NetworkServer.Spawn(obj);
36.         ServerStuff(obj, new Vector3(0f, 10f, 0f));
37.  
38.         //Once the server has done whatever it needs to do, you can choose if you want to have all clients do other actions.
39.         RpcDoAction();
40.     }
41.  
42.     [ClientRpc]
43.     public void RpcDoAction(){
44.         //Do broadcasting stuffs. Stuffs where all clients (local clients = LAN host, and remote clients = LAN clients) will do.
45.  
46.         //Because there exists a game object with client authority (meaning the game object's NetworkIdentity has "Local Player Authority" property
47.         //enabled), it means it's better to check for NetworkBehaviour.hasAuthority, rather than NetworkBehaviour.isLocalPlayer.
48.         if (!this.hasAuthority){
49.             //Clients with no authority do stuffs here.
50.  
51.             //Or if you want, you can do something that all other clients without authority of this game object can do.
52.             Ping(new Vector3(0f, 10f, 0f), Color.red);
53.         }
54.         else {
55.             //Do something in which the client itself has control over the game object of local authority.
56.  
57.             //Then do whatever you need to do that tells the player the unit has spawned, and all other enemies have taken notice of it.
58.             Ping(new Vector3(0f, 10f, 0f), Color.green);
59.         }
60.         return;
61.     }
62.  
63.     public void Ping(Vector3 position, Color color){
64.         //Pretend this is a function which pings a colored ! symbol on a minimap.
65.     }
66.  
67.     public void Update(){
68.         //Because this is a custom NetworkBehaviour script, this is attached to a game object that the client may use.
69.         if (Input.GetMouseButtonUp(0)){
70.             //When something occurred...
71.             ClientStuff();
72.         }
73.     }
74. }

 

I have some scripts I've been working on for my game here.

I built it for the new UI, if you know a bit about coding and linking buttons with functions you can have a look here.

Spoiler: Codes!

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using UnityEngine.Networking;
4.  
5. public class NetworkHelper : MonoBehaviour {
6.  
7.     public NetworkManager manager;
8.  
9.     public void StartHost()
10.     {
11.         manager.StartHost();
12.     }
13.  
14.     public void StartClient()
15.     {
16.         manager.StartClient();
17.     }
18.  
19.     public void StartServer()
20.     {
21.         manager.StartServer();
22.     }
23.  
24.     public void Stop()
25.     {
26.         manager.StopHost();
27.     }
28.  
29. }

^SInce the functions are public you can directly tie them to button functions. Easy!

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using UnityEngine.Networking;
4.  
5. public class NetworkPanel : MonoBehaviour {
6.  
7.     [Tooltip("The main NetworkManager you have in your scene")]
8.     public NetworkManager manager;
9.     [Tooltip("The panel the player sees before they are in-game")]
10.     public GameObject startPanel;
11.     [Tooltip("The panel the player sees whilst in the game (usually a stop button and some information)")]
12.     public GameObject inGamePanel;
13.  
14.     void Update()
15.     {
16.         if (!NetworkClient.active && !NetworkServer.active && manager.matchMaker == null)
17.         {
18.             startPanel.SetActive(true);
19.  
20.             inGamePanel.SetActive(false);
21.         }
22.  
23.         if (NetworkServer.active || NetworkClient.active)
24.         {
25.             startPanel.SetActive(false);
26.  
27.             inGamePanel.SetActive(true);
28.         }
29.     }
30. }

^Another script I made for you to enable and disable UI panels, so it isn't as cluttered!

If you like these it would be awesome if I can get some feedback on them. I'm a student learning coding for a hobby and potential career.

 

This is a very nice start with networking i think might refer to the new beta standard asset network using the new UI as lobbymanager as well

 

I did this tutorial this morning. Itd very good. Nice job. The only thing that needs rework is the last page. I could not find the package to import for your lobby. Still the people at photon have much better tutorials, but this is one of the better tutorials I have seen from unity. I hate tutorials where they just give you the code and your left to reverse engineer it.

 

Would love a javascript version

 

I wish you would write something like this but for setting up match making service for a game

 

Thanks for this.
Looking forward to the lobby updates.

Secondly, a lot of the example on the web, including this one are for FPS, but what if I'm writing a board game where each player (and there can be more than 2), gets a turn to select their own pawns and select which tile they should move to.
Not sure if a concept like that could be touched upon in the docs.
I'm guessing that the pawns should be created on the server only and spawned, then hit detection made from the client, but acknowledged on the server.
Hence, the pawns should have a network identity and network transport component.

Anyway, Thanks again, and eagerly awaiting the updates

 

Not assuming anything, but for both, you can cover all bases. Unless you have other thoughts that the "Manual" has already covered?

 

I'm not completely sure I know what you are asking. But I think the answer is from the editor. Maybe this can better explain it. The cube shooting game, if you could finish that off by doing step by step lobby and Match Making, that would be awesome. And include how to create a matchmaking project Id.

 

Thanks, this is a large improvement. Just lay it all out to us with examples.

 

Before I start asking a ton of questions over the course of this thread, let me say THANK YOU for making this.

Okay, got a bunch of questions on this subject and a lot of it is really because much of uNet doesn't answer the "why" questions.

Some understanding/explanation of the NetworkTransform bits would be very useful including why one would want to use it. Many of the other tutorials out there pretty much ignore the NetworkTransform because its not clear what all the bits and switches are and subsequently just implement a series of SyncVar to sync transform state around. Similarly within the documentation, it suggests doing things like setting the sendInterval to 0 (for bullets) and using SetDirtyBits() to cause the updates to be sent. Why would I choose one over the other?

Why would I set the snapThreshold and what are some good values for it?

 

^ this, extrapolated across UNet.

 

Thank you for this good material!

The only thing I miss is the explanation of how the animations work in unet

 

Good stuff, thank you guys. Although it will be a starter guide it would be good to see a matchmaking setup that includes a custom UI demonstrating a few overrides, as I imagine that will be the direction most will be heading.

 

I'm currently picking apart the uNet asset on the asset store that comes with pong as a demo.

It's kinda hard to pick apart because there's several areas / scripts that hard wire it to 2 players only. As soon as you want more than 2 players it's a lot of work to make sense of where things are going wrong (using a byte value for player numbers was a bit inflexible to put it mildly)

So a comprehensive doc is very very much appreciated!

 

Page 13:

This only makes bullets fire for the Host (any player), any connected clients don't see the networked bullets they are firing. Unity 5.2.1f1

 

1. Check to see if the bullet prefab is registered.
2. Check to see if it's spawned on Server (host) side, aka, the spawning occurs in the [Server] only functions.

 

1. registered.
2. Bullets only spawn in host, and don't display or get spawned in clients.

 

Try NetworkServer.SpawnWithClientAuthority().

 

ah needed to add NetworkServer.Spawn(bullet) properly, bit of a gotcha there!

 

I'm finding that following this tutorial to the letter, sometimes when you start up a server and players join, the player object will get stuck where it spawned for some clients, other clients it's moving around fine, the bullets will move around and spawn fine. On both Online and localhost. Results are different every time, but happens all the time.

If there is some way of checking that the player is moving around and make it move around for everyone, it may help add stability to this demo. Is this kind of stalling of player objects due to processor speeds?

Or maybe Lobby is the only way to really synchronize this? If everyone is joining at the same time?

 

Hmm,

Code (CSharp):

1. [SyncVar]
2.     public int health = maxHealth;

I get "UNetWeaver error: SyncVar [System.Int32 Combat::health] cannot be static."

Code (CSharp):

1. // Draw health bar amount
2.         GUI.color = Color.green;
3.         GUI.backgroundColor = Color.green;
4.         GUI.Box (new Rect (pos.x - 25, Screen.height - pos.y + 21, [U]Combat.health[/U] / 2, 5), ".", healthStyle);

How do i fix this in UNET?

 

1. Your health should be inside a class. Anything outside of a class is considered static.

2. To get health, you need to obtain a reference to your class containing the Health variable. Then you access the class member from the referenced class.

For more info on how to use C#, check out a few StackOverflow questions.

 

it's not directly related to this tutorial but, when running several clients on the same machine and switiching between them, the player object will freeze up on some clients.

Is there a way to force this from not happening? dirty is fine.

 

FYI, for the Multiple Players section I had to set 'Local Player Authority' in the Network Identity script on the player game object in order for the host to see the client move (Unity 5.3).

 

There's a change made in 5.2.3f1 where if the Unity Editor loses focus, the whole Unity Editor will pause whatever you are playing until it regains focus. This is happening on my end, as well as 5.3.0f4, so I don't know if that is what you're experiencing.

 

You can fix that by checking "run in background" on your network manager object.

 

I have this enabled already, I think it is something else. It's not the network manager not running in the background that is causing it.

When the Unity editor loses focus, it pauses all game objects. This includes game objects where you put your network manager script onto. Your network manager is keeping the connection open between the server and the client, but because all the updates are not happening, there is no data going through the connections.

That is what I am seeing when I'm doing local LAN testing.

 

Can you add something about syncing physics over unet. Like client trying to push a ball. Right now it seems to stick and I can not find much info on it.

Thanks

 

The Lobby asset now has an asteroids game which uses physics, might be worth checking that out.

 

Checking it out. Thanks for the reply.

[Edit]
Hmm, blue player still has some problems with physics. But it is a step in the right direction.
On the client the blue player can travel right through asteroids and the blue player position is off from the host at times, but it is definitely closer than anything I have seen so far. At least I can get an idea of how it is done. Who would have thought a network game where you kick a ball around would be so difficult.

Thanks, very, very much!
You have no idea how much I appreciate your reply.

 

would be nice if the manual could get an update, pages like this seem to reference the old components not in 5.2 http://docs.unity3d.com/Manual/class-NetworkTransform.html

 

There's just too many changes going on, that they couldn't keep up with pace. The APIs are changing so often, I would be guessing these manual articles will update when 5.4 or 5.5 is released next year.

 

It is very nice to see that you actively work on improving the UNET documentation.
I would like to suggest an addition to the docs which is rather small but significant:

In the docs, the general object creation flow is described, including networked spawning and object destruction for non-player objects. In addition, the spawn flow is described for player objects which are special networked objects. However, the list for the player objects does NOT include the flow of callbacks when a client disconnects and a player object is removed. This should be added to the list as it is very important to know for any custom NetworkManager implementations.

 

Sound constructive feedback. I never played with custom NetworkManager implementations before, so I couldn't give much. Hopefully, your feedback guarantees a response.

 

Very good tutorial thank you.
One request:
Can you please explain the best/easiest way to connect two different projects or two different scenes with unet? For example on the host pc will have the game and on client mobile devices to send triggers (e.g., controlling avatar animations etc.)

 

Excellent!
One little thing: players still respawn on vector zero?

 

Something has changed in unity. I see this behavior in my game and I see it in your demo. At the bottom of page 17, this statement is incorrect.

Save the project  Build and Run the game and see health bar on the player  If a player shoots another player now, the health goes down on that particular client, but not on other clients.
Player State (Networked Health)

This is your section where you add the NON - networked health, but the health acts networked, I see the health change on both clients. On my game, last night I added a treasure chest. When you bump into it; it plays the open animation and stays open. I have a variable "isOpen" I only play the open animation if its false (the chest is not already open). So, on one client I bumped into it and watched it open and to my surprise it also animated on the other client and the public variable was in sync. Yet there is not network indentity on the chest, no network transform and no sync variables. The only thing about the chest is it is not spawned, it's in place at design time and doesnt need to be spawned at run time.

 

For all graphics use the same style with light background.

 

I also would suggest that you have two versions: One using the standard and one doing it all in code.

 

I would as well. However, since I want to learn C# (as Unity wants us to do...), I'd prefer the javascript version to be more of a translating-guide. So that while the end result will be Javascript, the process will help us learn some of the C#, which would make it easier for us in the future to pick up more and finally switch over.

 

Eric,
When are you going to finish this tutorial?

 

please continue writing this document!
looks like it'll be the recommended start for unet beginners in the future.

 

You got to actually "tag" Erik like so in order to get his attention:

@Erik Juhl

But yeah, I'm also curious to know.