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NetworkTransform

The position, rotation, and scale of a NetworkObject is normally only synchronized once when that object is spawned. To synchronize position, rotation, and scale at realtime during the game, a NetworkTransform component is needed. NetworkTransform synchronizes the transform from server object to the clients.

NetworkTransform covers most use cases for synchronizing transforms. For some special cases such as really fast paced games a custom implementation with a different interpolation algorithm might be better.

tip

You can have multiple NetworkTransform components on child objects of your network object to synchronize individual positions of child objects.

Restricting Synchronization#

Quite often not all transform values of a GameObject need to be synchronized over the network. For instance if the scale of the GameObject never changes it can be deactivated in the syncing scale row in the inspector. Currently deactivating synchronization only saves on CPU costs but in the future it will also reduce the bandwidth used by NetworkTransform`.

Thresholds#

The threshold values can be used to set a minimum threshold value. Whether to properly scale to your project's world unit scale or to reduce the frequency of synchronization updates, changes below threshold values will not be synchronized. For example, if your NetworkTransform has Interpolate enabled you might find that you can lower your position threshold resolution (i.e. position threshold value increased) without impacting the "smoothness" of an object's motion. Increasing the threshold value (lowering the resolution of synchronization updates) will reduce the frequency of when the object's position is synchronized which translates to reducing bandwidth consumption.

note

Many small changes below the threshold will still result in a synchronization of the values as soon as all the accumulative changes cross the threshold.

Local Space#

By default NetworkTransform synchronizes the transform of an object in world space. The In Local Space configuration option allows to switch to synchronizing the transform in local space instead.

Using local space can improve the synchronization of the transform when the object gets re-parented because the re-parenting will not change the local space transform of the object but would modify the global space position.

Interpolation#

Check the Interpolate setting to enabled interpolation. Interpolation is enabled by default and is highly recommended. With interpolation enabled the NetworkTransform smoothly interpolates incoming changes to position, rotation and scale. In addition interpolation buffers the incoming data with a slight delay and applies additional smoothing to the values. All these factors combined result in a much smoother transform synchronization.

When Interpolate is disabled changes to the transform are applied immediately resulting in a less smooth position and more jitter.

note

The NetworkTransform component only interpolates client-side. For smoother movement on the host or server, users may want to implement interpolation server-side as well. While the server will not have the jitter caused by the network, some stutter can still happen locally, for example if movement is done in FixedUpdate with a low physics update rate.

Example banner
Graphic of a buffered tick between the server and a client (i.e. interpolation)

ClientNetworkTransform#

NetworkTransform always synchronizes positions from the server to the clients and position changes on the clients are not allowed. Netcode for GameObjects comes with a sample containing a ClientNetworkTransform. This transform synchronizes the position of the owner client to the server and all other client allowing for client authoritative gameplay.

You can use the existing ClientNetworkTransform in the Multiplayer Samples Utilities package.
To add the Multiplayer Samples Utilities package:

  • Open the Package Manager by selecting Window > Package Manager.
  • Select the plus button (+) > Add from git URL....
  • Copy and paste the following Git URL: https://github.com/Unity-> Technologies/com.unity.multiplayer.samples.coop.git?path=/Packages/com.unity.multiplayer.samples.coop#main
  • Select Add.

Optionally, you can directly add this line to your manifest.json file: "com.unity.multiplayer.samples.coop": "https://github.com/Unity-Technologies/com.unity.multiplayer.samples.coop.git?path=/Packages/com.unity.multiplayer.samples.coop#main"

You can also create your own ClientNetworkTransform by deriving from NetworkTransform, overriding the OnIsServerAuthoritative virtual method, and returning false:

Packages/com.unity.multiplayer.samples.coop/Utilities/Net/ClientAuthority/ClientNetworkTransform.cs
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See full example on GitHub