This sample contains a demonstration for how to manage level synchronization between server and clients when using the netcode package.

• The main module is the NetcodeLevelSync.cs file which implements the networked level sync flow. It does no scene load/unloading itself as that is very use case specific.
• The LevelSync_Bootstrap scene contains a subscene based level flow which demonstrates how to make use of the networked sync module.
  • It has a UI which makes use of the LevelManager.cs as entry point.
  • It uses LevelTracker* systems to handle loading/unloading routines.

NetcodeLevelSync implements the following flow:

• Server initiates level loading
  • Disable ghost sync (NetworkStreamInGame on all connections)
  • Unload current level and start loading the new level
  • Send RPC command to connected clients telling them to also switch levels
• When client receives the RPC command
  • Disable ghost sync (NetworkStreamInGame on server connection)
  • Unload current level and start loading next one
  • When done loading send RPC to server signalling you are ready
• When server has received ready message from all clients and is himself done loading
  • Enable ghost sync (NetworkStreamInGame on all connections)

NetcodeLevelSync is controlled through LevelSyncStateComponent data.

public struct LevelSyncStateComponent : IComponentData
{
    public LevelSyncState State;
    public int CurrentLevel;
    public int NextLevel;
}

The valid level sync states are

public enum LevelSyncState
{
    Idle,
    LevelLoadRequest,
    LevelLoadInProgress,
    LevelLoaded
}

• Normally the state will be Idle.
• When server starts level loading he should place the state in LevelLoadInProgress
• When a command to load a new level has arrived the client will see the LevelLoadRequest and needs to react to that by starting the level load routine himself and setting state to LevelLoadInProgress.
• When either server or client are done loading they should set the state to LevelLoaded
• State will go back to Idle when processing is done.

A good way to see the flow more clearly is to have a look at the test for it, as it goes though all the steps in a simple way in one file. See SceneAutomationSystems.cs