Help Wanted - [MLAPI] NotServerException for Changing Ownership of XR Interactable

Hello!

I am working on a virtual reality multiplayer game and have run into an issue with MLAPI. The game centers around a ball spawned by and owned by the server that clients can grab onto and move around. I am trying to get the ball position to update and propagate across the server to other clients by changing the ownership of the ball to the player upon grabbing it. However, in my script attached to the ball, a NotServerException is thrown for
GetComponent<NetworkObject>().ChangeOwnership(id);
even despite this ChangeOwnership() method being called in a server RPC method with RequireOwnership set to false. How can I fix this?

Thanks in advance!

 

Can you share the code you are using? Is maybe your ServerRpc function on a MonoBehaviour instead of a NetworkBehaviour?

 

Absolutely, here is my code for the script attached to the ball. The script right now inherits from XRGrabInteractable to get the methods that trigger upon grabbing the ball, so I don't think it can inherit from NetworkBehaviour as well. Could I try something like having the method in this script call another script that inherits from NetworkBehaviour to make the serverRPC method work? Thank you for your help!!

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.XR.Interaction.Toolkit;
using MLAPI;
using MLAPI.Messaging;

public class BallGrabInteractable : XRGrabInteractable
{
//I've omitted some unnecessary code here

[ServerRpc(RequireOwnership = false)]
private void changeDiscOwnershipServerRpc(ulong id)
{
GetComponent<NetworkObject>().ChangeOwnership(id);
}

[ServerRpc(RequireOwnership = false)]
private void resetDiscOwnershipServerRpc()
{
GetComponent<NetworkObject>().RemoveOwnership();
}
protected override void OnSelectEntered(XRBaseInteractor interactor)
{
ulong cID = 0;
//Method to set cID to the player ID of the player who's grabbed the ball
changeDiscOwnershipServerRpc(cID);
base.OnSelectEntered(interactor);
}

protected override void OnSelectExited(XRBaseInteractor interactor)
{
resetDiscOwnershipServerRpc();
base.OnSelectExited(interactor);
}
}

 

Ah yes, it no longer gives the NotServerException when changing ownership now that I've moved it to a different script that inherits from NetworkBehaviour, but even still the position of the ball doesn't update on the server. The ball stays where it is even after the player throws it and the ownership is changed. Any ideas on how to fix this?

 

Ping .. Any news on this?

 

Hi,
I really appreciate your fast support. In particular - since this is a widely discussed challange I am facing e.g.:
- https://forum.unity.com/threads/move-other-players-with-xr-grab-interactable.1479960/
- https://forum.unity.com/threads/xri-netcode-client-grab.1492559/
- https://forum.unity.com/threads/how-to-change-ownership-on-interactables-in-netcode.1529314/
- https://gamedev.stackexchange.com/questions/199174/unity-xr-toolkit-and-mirror-networking-grabbing

I am using:
- 2022.3.16f1
- Netcode for GameObjects 1.7.1
- Relay 1.0.5
- XR Interaction Toolkit 2.5.2
- 2 Meta Quest 3

Following the SETUP mentioned here:
-

-

GOAL: Each player is able to spawn objects that can be grabbed (XR Grabble) and moved arround by both players.

PROBLEM: If client player grabs, moves or rotates the object, it snaps back to the old position after exiting select. I'm facing the problem even if i requestchange ownership via serverRPC. Reuqesting the ownership slightly changes the behavior - meaning that very small changes of rotations seam to be transmited to the sever somehow.

ASSUMPTION: The missmbehavior ist somehow related to the fact that the grabbed object is reparented for interaction - but I am not sure.

In the attachement you will find a screenshot of the object.In addition I attached the changeOwnership script.

Does it make sense?
Dod you need any additional information?
Is there any sample showing how to have a xr grabbable object being moved arround by two players with netcode for GameObjects and Relay? I means this seamas to me a very obvious XR use case.

Your help is very appreciated! Hope to hear from you soon!

BR,
Andreas

 

Solution is to use a Client Network Transform, which is mentioned here: NetworkTransform | Unity Multiplayer Networking (unity3d.com)