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ClientRpc

A ClientRpc can be invoked by the server to be executed on a client.

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Declaring a ClientRpc#

Developers can declare a ClientRpc by marking a method with [ClientRpc] attribute and making sure to have ClientRpc suffix in the method name.

[ClientRpc]
void PongClientRpc(int somenumber, string sometext) { /* ... */ }

Invoking a ClientRpc#

Developers can invoke a ClientRpc by making a direct function call with parameters:

void Update()
{
if (Input.GetKeyDown(KeyCode.P))
{
PongClientRpc(Time.frameCount, "hello, world"); // Server -> Client
}
}

Marking method with [ClientRpc] attribute and putting ClientRpc suffix to the method name are required, otherwise it will prompt error messages:

// Error: Invalid, missing 'ClientRpc' suffix in the method name
[ClientRpc]
void Pong(int somenumber, string sometext) { /* ... */ }
// Error: Invalid, missing [ClientRpc] attribute on the method
void PongClientRpc(int somenumber, string sometext) { /* ... */ }

[ClientRpc] attribute and matching ...ClientRpc suffix in the method name are there to make it crystal clear for RPC call sites to know when they are executing an RPC, it will be replicated and executed on the client-side, without necessarily jumping into original RPC method declaration to find out if it was an RPC, if so whether it is a ServerRpc or ClientRpc:

Pong(somenumber, sometext); // Is this an RPC call?
PongRpc(somenumber, sometext); // Is this a ServerRpc call or ClientRpc call?
PongClientRpc(somenumber, sometext); // This is clearly a ClientRpc call

To Send to One Client, use ClientRpcSendParameters#

The following code provides an example of using ClientRpcSendParameters, which will allow you to send a ClientRpc to a specific Client connection(s) whereas the default Netcode for GameObjects's behavior is to broadcast to every single client.

private void DoSomethingServerSide(int clientId)
{
// If is not the Server/Host then we should early return here!
if (!IsServer) return;
// NOTE! In case you know a list of ClientId's ahead of time, that does not need change,
// Then please consider caching this (as a member variable), to avoid Allocating Memory every time you run this function
ClientRpcParams clientRpcParams = new ClientRpcParams
{
Send = new ClientRpcSendParams
{
TargetClientIds = new ulong[]{clientId}
}
};
// Let's imagine that you need to compute a Random integer and want to send that to a client
const int maxValue = 4;
int randomInteger = Random.Range(0, maxValue);
DoSomethingClientRPC(randomInteger, clientRpcParams);
}
[ClientRpc]
private void DoSomethingClientRPC(int randomInteger, ClientRpcParams clientRpcParams = default)
{
if (IsOwner) return;
// Run your client-side logic here!!
Debug.LogFormat("GameObject: {0} has received a randomInteger with value: {1}", gameObject.name, randomInteger);
}
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Server can invoke a client RPC on a Network Object. The RPC will be placed in the local queue and then sent to a selection of clients (by default this selection is "all clients"). When received by a client, RPC will be executed on the client's version of the same Network Object.

Invoking a Client RPC from the Host.#

As the host is both a client and a server, if a host invokes a Client RPC, that RPC will be executed on the host too in addition to other clients.

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Client Hosts can invoke Client RPCs on Network Objects. The RPC will be placed in the local queue and then, after a short delay the client RPC will be executed on the Client Host, and sent to the other clients. When client RPC is received by the client - it is executed on the Client's version of the same Network Object.

See examples of how these were used in Boss Room.

See also#