NetworkTransform.useHalfFloatPercision causes initial sync to not work properly

[AlexEnnerfelt]

Description

I just updated to 1.4.0
Using NetworkTransform.useHalfFloatPercision seems to cause an issue on initial value sync where it doesn't sync the position of an object before starting to write the deltas. This results in objects being offset by arbitrary distances.

I am using the ClientNetworkTransform as it is implemented in the example.

Reproduce Steps

1. Create an object with a ClientNetworkTransform with useHalfFloatPercision = true
2. Spawn it with ownership
3. Connect with another client and spawn the same object with ownership

Actual Outcome

Sometimes, (unclear what the pattern is) one or both of the objects are offset from their actual position on the owner client, and only updating the delta.
Turning off useHalfFloatPercision (even at runtime) resolves this.

Expected Outcome

For the position on the owner client to be synced properly on the other clients

Environment

• OS: Windows 11
• Unity Version: 2022.2.17
• Netcode Version: 1.4.0
• Netcode Commit: [e.g. https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/commit/ba418fa5b600ad9eb61fab0575f12fbecc2c6520]

Additional Context

Add any other context about the problem here. Logs, code snippets would be useful here but please also consider attaching a minimal Unity project that reproduces the issue.

[NoelStephensUnity]

@AlexEnnerfelt
This could be similar to an issue I saw with parenting and scale.
Do the objects move upon spawning at a specific location or are they stationary after that?
It would help to have an example project and/or description of:

• how the objects are being positioned initially
• if the objects move after being spawned

When instantiating and then spawning with ownership there could be a possible bug depending upon how you handle assigning the client owned object being instantiated. It would help if you could take a look at the attached project and make adjustments to it to better reflect how your project is instantiating and spawning the network prefabs:
OwnershipSpawning_2549.zip

I whipped this together pretty quickly, so don't read too much into how I set it up since there are several ways to accomplish the same thing. I chose to spawn with ownership, apply an initial spawn position to a NetworkVariable so when spawned on the client side (owner) it would apply the new spawn position on the owner side (i.e. applying the position on the server side when spawned with ownership to something other than the server could be the issue you are experiencing).

The below are the results of the default settings for the above project with 1 host and 2 clients:

There are a couple of ways to handle spawning and ownership when you want to set a default position, but I don't know the context of what is spawning the objects and how the initial position is being set and what is setting the initial position. So, if you wouldn't mind either describing how your project is different and/or (preferred) making adjustments to this generic project and sending me the zip for the Assets and Packages folder I would be able to faster verify the issue.

[NoelStephensUnity]

@AlexEnnerfelt
I believe the fix for this was in #2538 and should be in the develop branch at this time.
With no clear replication path it is difficult to determine if that will resolve your issue.
If you wouldn't mind testing your project against the develop branch to confirm it would be very helpful.
You can do this by replacing your com.unity.netcode.gameobjects manifest file entry with this:
"com.unity.netcode.gameobjects": "https://github.com/Unity-Technologies/com.unity.netcode.gameobjects.git?path=com.unity.netcode.gameobjects#develop",

What I think was happening is if you just spawned the object with no further change in position then the initial synchronization state would be applied multiple times (which if you didn't move the objects after they were spawned would indeed cause the issue you are describing). The fix is to ignore the synchronization state (after it is already applied) on non-authoritative instances.

[Daniel4144]

I got a very similar issue, but the initial position is correct. When I transfer ownership to a client, the object jumps to a wrong position. This also only happens with half float precision enabled.

Unfortunately I can't test the develop branch, because there I get some errors.

[NoelStephensUnity]

@Daniel4144
Thank you for your feedback on this issue. I will setup a similar scenario on my end to see if I can replicate the issue using the develop branch (soon to be v1.5.1)

[NoelStephensUnity]

@Daniel4144 @AlexEnnerfelt
I am going to be looking at this a bit more in detail (have yet to replicate it using v1.5.1), but wanted to see if you are still experiencing this issue when using v1.5.1?

If you are using full precision, then you might switch to half precision until the next patch update that will include the following fix for full precision when interpolation is enabled: #2624

[Daniel4144]

@NoelStephensUnity
I haven't updated yet due to some other errors in the new version, still at v1.4.0. I will let you know when I have the time to update.