Modding:Synchronization

As a modder, if haven't had experience with multiplayer environments, the learning curve can be a bit steep at first. This document is here to help you with common pitfalls. As a general rule of thumb, the Vintage Story Client<->Server Architecture is server authoritative. That means the server has the sole authority over drops, crafting, entity simulation, chunk loading, and so on... which allows for some baseline of hacking protection.

Client to Server

Player

The game client automatically sends player position and player controls, i.e. EntityControls to the server. This object can tell you if the player currently walks, sneaks, is using a held item and more.

Blocks

Code for block interactions are called on the client and server side, however when you implement OnBlockInteractStart you must return true if you want the action to also get executed on the server.

Entities

Entity interactions are always synced to the server and the same is called there.

Inventory

If the player has any opened inventory, all relevant inventory code must be executed on the client and the server. inventory.Open() and .Close() must also be called on both sides when the gui is opened/closed.

Server to Client

If you run code on the server alone, some of it may need to be explicity synchronized to the client.

Blocks

A call to SetBlock() and ExchangeBlock() is automatically synced.

If you change any data on a block entity, you usualay have to call `MarkDirty()` inside the block entity. It will resend all block entity data to all nearby clients.

Inventory

Changing inventory contents usually requires you to call slot.MarkDirty() so that the client sees the change.