Client that is not the owner can move a ClientNetworkTransform locally

[Daniel4144]

Maybe this will be solved with other upcoming fixes regarding NetworkTransform synchronization, but since I could still reproduce it with the develop branch, I am reporting it just to be safe.

Description

When a NetworkObject with a ClientNetworkTransform is owned by a client (not host) while another client joins, the newly joined client is able to move the object locally, until the owning client moves the object at least once.

Reproduce Steps

Requires at least 3 instances
Requires an active NetworkObject with a ClientNetworkTransform in the scene where a client can take ownership of

1. Start a host
2. Start client 1
3. Have at least one NetworkObject with a ClientNetworkTransform that is owned by client 1
4. Start client 2
5. Move the object from (3.) on client 2 -> The object is moving, although is should not
6. Move the object on client 1 (owner)
7. Move the object on client 2 -> The object is not moving anymore, as it should

There is not much involved in reproducing the issue, but I can provide a very minimal project where I could reproduce it in the editor.

Environment

• OS: Windows 10
• Unity Version: 2021.3.24f1
• Netcode Version: 1.5.1 and develop branch (both same behaviour)

Additional Context

Both in-scene objects and spawned objects behave like this.
Does not seem to be connected to half-precision or interpolation unlike other recent NetworkTransform issues.

[NoelStephensUnity]

@Daniel4144
Once #2636 is merged (or just test the branch itself), you might see if that resolves the issue (or I can circle back to this when I have some time).

[NoelStephensUnity]

@Daniel4144
I am having a hard time replicating this issue using v1.5.1 and even tried it on the develop branch (to be released v1.5.2).

The code that I am using to move some owner/client authoritative NetworkTransforms is this:

    private void FixedUpdate()
    {
        if (!IsSpawned || !IsOwner && !IsHost)
        {
            return;
        }
        else
        {
            var vertical = Input.GetAxis("Vertical");
            var horizontal = Input.GetAxis("Horizontal");

            if (vertical == 0.0f && horizontal == 0.0f)
            {
                return;
            }
            var previousPosition = transform.position;
            transform.position = Vector3.Lerp(transform.position, transform.position + vertical * Speed * transform.forward, Time.fixedDeltaTime);
            var rotation = transform.rotation;
            var euler = rotation.eulerAngles;
            euler.y += horizontal * 90 * RotSpeed * Time.fixedDeltaTime;
            rotation.eulerAngles = euler;
            transform.rotation = rotation;

            /// We store this to handle a collision rotation issue: <see cref="Teleport(Vector3, Quaternion, Vector3)"/>
            m_PreviousRotation = transform.rotation;

            if (!IsOwner)
            {
                Debug.Log($"[Client-{NetworkManager.LocalClientId}] is moving NetworkObject ({NetworkObjectId}) owned by Client-{OwnerClientId}. Previous ({previousPosition}) Updated({transform.position})");
            }            
        }
    }

The above adjustments I applied to the PlayerMovement script in our testproject's teleport sample.

I tested by making a stand alone build and running that as a client and running the host in the editor.
The console log output looked like this:

Which shows it applies the changes to the non-owned object, but the next frame update during FixedUpdate if I am still trying to move it the transform values are set back to the original position (and rotation but I am not logging that).

If you could include a small project that replicates the issue it would help me figure out where the issue might be.

[Daniel4144]

@NoelStephensUnity
I think there was a misunderstanding, the issue only shows with at least three instances with one host plus two non-host clients. One client is the owner and the other client is moving the object. The host is doing nothing here.
Also, I think your script cannot replicate the issue, because it does not allow a non-host, non-owner client to move the object.

Here is a minimal project to quickly replicate it, it uses the movement code you provided above without the spawned/owner/host check at the beginning:
netcode-issue-networktransform-latejoin.zip

The exact steps to reproduce it with the included project: (I have tested with both, build and editor playmode)

1. Start three instances, I will call them (1), (2), (3)
2. Click "Start Host" in (1)
3. Click "Start Client" in (2)
4. Click "Take Ownership" in (2)
5. Click "Start Client in (3)
6. Move the object with WASD in (3) <-- here is the unexpected behaviour - the object moves in (3), but its position should be reset, because (2) is the owner
7. Move the object in (2) --> from now on the objects are in sync, even if trying to move with non-owning (3)

The crucial parts are that a non-host client (2) is the owner and that after client (3) connected, the object was not moved yet by the owning client (2).

I just noticed another weird problem with the project I provided, maybe you could quickly test it:
With one host and one client, where the client is the owner of the object: After the client disconnects while it had ownership, the host cannot move the object (although the inspector says it has ownership). Even worse, I cannot shutdown the host anymore.

[NoelStephensUnity]

@Daniel4144
Thank you very much for the sample project and more detailed steps.
I see the issue and have applied a fix in #2636.
This fix will be applied to the next minor version update of NGO (after the soon to be released v1.5.2 patch)
👍