Custom RPC target

[viral gyro]

Reading the docs but I'm still a little confused on how to actually use the custom targets since it doesn't provide an example. I'd like to send an RPC to both the server and owner of an object (host might also be owner). It's for a hidden roles game. Any help would be much appreciated, thank you!

[mortal hollow]

You use [Rpc(SendTo.SpecifiedInParams)] and pass in a RpcTarget with the IDs you want.

[tame summit]

You would use RpcTarget.Group() then add the Server Client ID and the Owner Client Id to the list

[viral gyro]

Right, but how do I construst that RPC target? I'm not sure how to use these BaseRpcTargets shown in the screenshot

[mortal hollow]

Shown in the example here: https://docs.unity3d.com/Packages/com.unity.netcode.gameobjects@2.4/manual/advanced-topics/message-system/rpc.html#completing-the-ping-example

Just use RpcTarget.Group instead of Single as noted above

[viral gyro]

Great thanks, do you know why the following doesn't work, and does the server have a client id?

[tame summit]

you have to initialize an array first

[mortal hollow]

0 or use this: https://docs.unity3d.com/Packages/com.unity.netcode.gameobjects@1.12/api/Unity.Netcode.NetworkManager.html#Unity_Netcode_NetworkManager_ServerClientId

[tame summit]

might be easier to use a NativeList

or cache it if its just a 2 player game

[viral gyro]

I have. It's because RpcTarget is a class, not an object, and Group is a non static method. I think it's because I'm referencing from a non networkbehaviour class, so just getting the one from the network manager

[tame summit]

Oh I see yea. RpcTarget is part of NetworkBehaviour

[viral gyro]

this should work now. Is it okay to call an rpc on a network object that was just spawned on the network?

And will it matter if the owner is the host? The 2 ids would then be the same

[tame summit]

player.Rpctarget should work as well

[viral gyro]

I'm just worried that it will call it twice on the host

[viral gyro]

yeah that's nicer

[mortal hollow]

You can use [AllowTargetOverride = true)] and just send to one ID if the IDs are the same and you are worried about a repeat send.

Not sure if it would actually send twice though.

[tame summit]

Addcard sounds like it should only be something run on the host anyways

Also keep in mind for card games, there is no hiding information from the host

[viral gyro]

Yeah I'm aware

I'm trying to write code that will work for both host and server

[viral gyro]

I'll have to test. My guess is that it won't, but I can always turn it into a set if needed

[mortal hollow]

There's not much to consider when doing this. Just avoid using Host specific properties like IsHost and that's about it.

[viral gyro]

I want to add the true value of the card to both the server and owner, whilst an 'unkown' value is added to every other client

            // Create players and deal cards
            foreach (ulong clientId in NetworkManager.Singleton.ConnectedClientsIds)
            {
                // Spawn player on network
                QUOP_Player player = NetworkManager.Singleton.SpawnManager.InstantiateAndSpawn(playerPrefab.GetComponent<NetworkObject>(), clientId, true).GetComponent<QUOP_Player>();
                for (int i = 0; i < starting_cards; i++)    // Deal starting hand
                {
                    CardType card = deck.Draw();
                    ulong[] targets = { player.OwnerClientId, NetworkManager.ServerClientId };
                    // Send true card to server and owner
                    player.AddCardRpc(card, player.RpcTarget.Group(targets, RpcTargetUse.Temp));
                    // Send unkown to everyone else
                    player.AddCardRpc(CardType.UNKNOWN, player.RpcTarget.Not(targets, RpcTargetUse.Temp));
                }
            }

so I think that should now do I what I want

Hard to read, sending a screenshot instead

(This is all ran from the server)

What's stopping the owner of the object calling this rpc?

I only want the server to be able to run it

like is it possible to have a hacked client which runs this rpc?

[mortal hollow]

You can use [RequireOwnership = true]

https://docs.unity3d.com/Packages/com.unity.netcode.gameobjects@2.4/manual/advanced-topics/message-system/rpc.html#rpcattribute-parameters

[mortal hollow]

I mean once you have a hacked client, the cat is out of the bag. Not much you can do.

[viral gyro]

If you specify that only a server should be able to run an RPC, surely that helps matters?

[viral gyro]

I don't see any option to make is server only?

[mortal hollow]

Yep! Anti-cheat is about heightening the barrier to entry for cheating, not full prevention. Any sort of potential prevention is always good.

[mortal hollow]

If this NetworkBehaviour is spawning players, it should be owned by the server.

Meaning if you use [RequireOwnership = true], only the server can call it.

[viral gyro]

It's an rpc in a player object that adds a card to that players hand

the scipt that spawns the players and manages the game is just a MonoBehaviour

[mortal hollow]

Ah, I see.

[tame summit]

I would flip it around and make the game manager a network object

[mortal hollow]

Best you can do in that case is probably just put if (!IsServer) return; at the top of the function.

[viral gyro]

Yeah maybe that's the way of going about it? I'll have to have a bit of a think

[viral gyro]

Wait that still wouldn't work as I need function to do stuff on clients

[mortal hollow]

Or yeah, make the Game Manager a NetworkObject and make this RPC inside of the Game Manager. Technically something like a Game Manager should handle the networking and your player script should just just receive the result of the RPC and create the visual for the card.

[tame summit]

I use cloud code/save to manage game state in my card game prototype

[viral gyro]

I might do network object for both player and game manager, and then a monoscript for display based on player. Player object does need to call some server RPCs to tell server what action it is doing

Thanks for help both of you anyhow, much appreciated! Last question, is there a problem calling an RPC on a network object right after it is spawned?