Live Sync#

The current Omniverse Unity Connector allows unidirectional Live Sync from the Unity Editor to the Omniverse App.

Functions available with Live Sync#

  • Pass unidirectional processing from the Unity Editor to the Omniverse App using Live Sync.

  • Live Session Notification (Join/Left/Merge)

  • Real-time editing with Live Sync

    • Create GameObject

    • Delete GameObject

    • Change GameObject transform

    • Change GameObject parameters (Rename, Change visibility)

    • Change Material parameters

    • Bind material to mesh

    • Move GameObjects between hierarchies

    • Bind material to mesh

    • Light placement and editing

    • Camera placement and editing

How to use Live Sync#

The following conditions must be met to use Live Sync.

  • Use usd file on Nucleus

In Live Sync, USD file formats usd/usdc/usda can be used.

Export USD file#

Select [Omniverse]-[Export] from the menu to export usd to Nucleus.
Unity scene.

Create a session and join a Live Session#

Select [Omniverse]-Live Sync from the menu to display the Omniverse Live Sync window.
Omniverse Live Sync window.
Pressing the Validate button will confirm for Live Sync from the usd file on the specified Nucleus.
Note that usd files exported after the Unity Editor has been launched are the target file.
It is currently not possible to perform Live Sync without exporting after launching the Unity Editor.
Specify any session name in Create New Session and press the Create Session button.
Here we have specified a session name of “test”.
Create new session.
Available Sessions displays the name of the session you created.
It also shows [Connected to session “test”] in green.
[Connected to session "test"] in green.

Open usd file in USD Composer#

Launch USD Composer and open the usd file on Nucleus that you exported in the Unity Editor.
Click “LIVE” in the upper right corner to open the menu and select “Join Session”.
Join Session in USD Composer.
In the Live Session window, select “Join Session” and then “test”.
Push the “JOIN” button.
Live Session window.
USD Composer has now joined the “test” session.
joined the "test" session.

Check session participation in Unity Editor#

In the Omniverse Live Sync window of the Unity Editor, we could see that USD Composer had joined the session.
Confirm session join in Unity.
By moving the GameObject, make sure that the USD Composer participating in the Live Session is also updated in real time.
Confirm synchronization of transforms using Live Session.

Leave a session#

Press the “Leave Session” button in the Omniverse Live Sync window to leave the Live Session.
Leave session.

Join an already existing session#

In the Omniverse Live Sync window, you can join a session by selecting the session name in the Available Sessions list.
Join an already existing session.
You can also refresh the session list to the latest by clicking on the gray Refresh text.
Refresh session information.

Merge session into root usd#

Pressing the “End Session and Merge Changes” button in the Omniverse Live Sync window will merge the active session into the root usd.
Merge session.
Leave active session before merging.

Notification#

The Omniverse Unity Connector receives Live Session notifications from other Omniverse Apps and tools using the Omniverse Connector.

When using Live Sync, three events are acquired from outside.
You will be notified which of the users participating in the Live Session is trying to do what.

Event Type

Description

Join

User joined session.

Left

User left session.

Merge

The user has terminated the session and is about to initiate a merge.
Notifications are displayed in the Scene viewport of the Unity Editor.
Live Session Notification.

When notified of a merge process#

When an external user participating in a Live Session performs a merge, the Omniverse Unity Editor displays a message box prompting the user to leave the session.
When notified of a merge process.
Press OK button to leave the session.
If merged in Live Session, the session diff is merged against the root usd.
Therefore, the session itself will be discarded.

Live Sync when using prefab#

If you export with the “Prefab to Payload” checkbox checked in Settings, the prefab will be exported in multiple usd files.
The root usd references these from payload.
Live Sync when using prefab.
Updates to payloads during Live Sync are reflected in the current session with an override.
The original usd file referenced by payload is not updated.
Also, if a GameObject or material is added during Live Sync, the information is added to the current session.
During Live Sync, if you add new assets or prefabs to the scene on the Unity Editor side, they are not exported as usd as payload.

Limitations#

  • Currently, it is a one-way Live Sync from the Unity Editor to the Omniverse App and other Omniverse Connectors.

  • You must export once in the Unity Editor and then use Live Sync.

  • Physics does not support Live Sync.

Note

You must first Export a .usd from Unity to a Nucleus server and then Create a Live Sync Session from the recent export of the open Unity scene. Share the Omniverse URL with those that want to join the session. When in Live Sync changes to a scene in Omniverse will not apply to Unity, but changes in Unity will apply to Omniverse.

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