# Prefab Setup: CoherenceSync In this section, we will learn how to prepare a Prefab for network replication. ## Video tutorial Setting up basic syncing is explained in this video, from 1:00 and onwards: {% embed url="" %} ## Using the Coherence Hub You can let the coherence Hub guide you through your Prefab setup process. Simply select a Prefab, open the *GameObject* tab in the coherence Hub (*coherence > coherence Hub*) and follow the instructions.

## Step by step You can also follow the detailed step-by-step text guide below. ### **1.** Add `CoherenceSync` to your GameObject For a Unity GameObject to be networked through **coherence**, it needs to have a `CoherenceSync` component attached. Currently, only Prefabs are supported. If your GameObject is not a Prefab, `CoherenceSync` can assist you. First, create a new GameObject. In this example, we're going to create a Cube. ![](https://352971571-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOnNWMLfYsbCzCnIbNrcP%2Fuploads%2FKWnkQtWCMSqNGINigZO1%2FScreenshot%202022-07-06%20at%2012.33.45.png?alt=media\&token=b9e2f7f3-da45-4156-9486-df2779f070c6) Next, let's add the `CoherenceSync` component to this Cube. ![](https://352971571-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOnNWMLfYsbCzCnIbNrcP%2Fuploads%2FOwijeDRmXBy4eIh1e5IL%2FScreenshot%202022-07-06%20at%2012.37.53.png?alt=media\&token=f2aee424-1eb5-46fa-aa22-b73d24049d85) The `CoherenceSync` inspector now tells us that we need to make a Prefab out of this GameObject for it to work. We get to choose where to create it.

In this example, we'll be creating it in 📁 `Assets / Resources` by clicking **Convert to Prefab in Resources**. ![](https://352971571-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOnNWMLfYsbCzCnIbNrcP%2Fuploads%2FyzM57FUVgYR6JfK6kSQE%2Fimage.png?alt=media) #### 1.1 Networking an already existing Prefab If you wish to start networking a Prefab that already exists in your project, you have more options to get started: * Clicking on the *Sync with coherence* checkbox at the top of the Prefab inspector. * Manually adding the CoherenceSync component.

* Drag the Prefab to the *CoherenceSync Objects Window* you can find in *coherence > CoherenceSync Objects*.

Dragging a Prefab to the CoherenceSync Objects Window

#### **1.2 (Optional) Prefab variants** One way to configure your Prefab, instead of just adding `CoherenceSync` into it, is to fork a Prefab variant and add the component there. In our Cube example, instead of adding the component to the original Prefab, you can create a variant called **Cube (Networked)** and add `CoherenceSync` to it: {% hint style="info" %} Learn how to create and use Prefab variants in the [Unity Manual](https://docs.unity3d.com/Manual/PrefabVariants.html). {% endhint %}

This way, you can retain the original Prefab untouched. Another way to use Prefab variants to our advantage is to have a base Prefab using `CoherenceSync`, and create Prefab variants off that one with customizations. For example, **Enemy** (base Prefab) and **Enemy 1**, **Enemy 2**, **Enemy 3**... (variant Prefabs, using different models, animations, materials, etc.). In this setup, all of the enemies will share the networking settings stored in `CoherenceSync`, so you don't have to manually update every one of them. When the Prefab variant inherits the network settings from the Prefab parent, you can configure your Prefab variant with overrides in the *Configuration* window. When a synced variable, method or component action is present in the variant and not in the parent, it will be bolded and it will have the blue prefix beside it, just like any other override in Unity.

Prefab variant with overriden synced variables

### **2. Configure CoherenceSync** The `CoherenceSync` component will help you prepare an object for network synchronization during design time. It also exposes an API that allows us to manipulate the object during runtime. `CoherenceSync` scans all public variables and methods on any of the attached components, for example Unity components such as `Transform`, `Animator` , etc. This will include any custom scripts and even scripts that came with the Asset Store packages that you may have downloaded.

{% hint style="info" %} You can find out more about all of `CoherenceSync` properties [here](https://docs.coherence.io/1.0/coherence-sdk-for-unity/components/coherencesync). {% endhint %} ### **3. Select properties to replicate** Select which properties you would like to sync across the network. Initially, this will probably be the `Transform` properties: **position**, **rotation**, **scale**. Click the *Configure* button in the `CoherenceSync` Inspector. A new window will open, called *Configuration.* Click on the tab *Variables.* Since **position** is already selected, add **rotation** *and* **localScale***.*

Close the *Configuration* window. {% hint style="info" %} Tip: You can also configure variables, methods and components **on child objects** in the CoherenceSync hierarchy. To do that, simply select the desired object in the *Hierarchy* window, and the *Configuration* window will show information for that specific object — similarly to how the Inspector works. {% endhint %} ### **4. Add an input script** This simple input script will use WASD or the Arrow keys to move the Prefab around the scene. Click on *Assets > Create > C# Script*. Name it `Move.cs`. Copy-paste the following content into the file. {% code title="Move.cs" %} ```csharp using UnityEngine; public class Move : MonoBehaviour { public float speed = 1f; void Update() { float h = Input.GetAxisRaw("Horizontal"); float v = Input.GetAxisRaw("Vertical"); var spf = speed * Time.deltaTime; transform.position += transform.forward * (v * spf); transform.position += transform.right * (h * spf); } } ``` {% endcode %} Wait for Unity to compile the file, then add it onto the Prefab. ### **5. Disable input on replicated object** We have added a `Move` script to the Prefab. This means that if we just run the scene, we will be able to use the keyboard to move the object around. But what happens on other Clients where this object is not authoritative, but replicated? We will want the position to be replicated over the network, without the keyboard input interfering with it. Under *Configure*, click *Components*. ![](https://352971571-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOnNWMLfYsbCzCnIbNrcP%2Fuploads%2FRxo9V7M6dd66u1mUOAl3%2FComponent%20Actions.png?alt=media) Here you will see a list of Component Actions that you can apply to non-authoritative GameObjects that have been spawned by the network. Selecting *Disable* for your `Move` script will make sure the Component is disabled for network instances of your Prefab. ![](https://352971571-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOnNWMLfYsbCzCnIbNrcP%2Fuploads%2FeQQQ2uP8U1g2kmrQqGBs%2FDisable%20Move%20Component.png?alt=media) ### **6. Implementing your own Component Actions** By extending the `ComponentAction` abstract class, you can implement your own Component Actions. {% code title="ComponentAction.cs" %} ```csharp using UnityEngine; [System.Serializable] public abstract class ComponentAction { [SerializeField] internal Component component; public Component Component => component; public virtual void OnAuthority() { } public virtual void OnRemote() { } } ``` {% endcode %} Your custom Component Action must implement the following methods: * `OnAuthority` This method will be called when the object is spawned and you have authority over it. * `OnRemote` This method will be called when a remote object is spawned and you do not have authority over it. It will also require the `ComponentAction` class attribute, specifying the type of Component that you want the Action to work with, and the display name. For example, here is the implementation of the Component Action that we use to disable Components on remote objects: {% code title="ComponentAction.cs" %} ```csharp using Coherence.Toolkit; using UnityEngine; [ComponentAction(typeof(Behaviour), "Disable")] public class DisableBehaviourComponentAction : ComponentAction { public override void OnAuthority() { var b = Component as Behaviour; b.enabled = true; } public override void OnRemote() { var b = Component as Behaviour; b.enabled = false; } } ``` {% endcode %} ### **7. Additional CoherenceSync settings** From the `CoherenceSync` component you can configure settings for **Lifetime** (`Session-based` or `Persistent`, **Authority transfer** (`Request` or `Steal`), **Simulation model** (`Client Side`, `Server Side` or `Server Side with Client Input`) and **Adoption** settings for when local persistent entities are orphaned. There are also some **Events** that are triggered at different times. * `On Before Networked Instantiation` (before the GameObject is instantiated) * `On Networked Instantiation` (when the GameObject is instantiated) * `On Networked Destruction` (when the GameObject is destroyed) * `On Authority Gained` (when authority over the GameObject is transferred to the local client) * `On Authority Lost` (when authority over the GameObject is transferred to another client) * `On After Authority Transfer Rejected` (when GameObject's Authority transfer was requested and denied). * `On Input Simulator Connected` (when client with simulator is ready for Server-side with Client Input) * `On Input Owner Assigned` (when InputOwner was changed is ready) ### **8. Nested `CoherenceSync` components** It is possible to nest network entities into each other both at edit and at runtime. Doing it at runtime is semi-automatic, and only if you nest an entity deeply into a hierarchy (like a tool in the hands of a character), you need to add the `CoherenceNode` component to the nested one. For edit-time nesting instead, the `PrefabSyncGroup` needs to be placed on the root object. ## Helper scripts {% hint style="info" %} Helper scripts and samples can be found [here](https://docs.coherence.io/1.0/additional-resources/helper-scripts). These cover things such as: * Spawning a player * Basic inputs to get Game Objects moving * Score keeper * Displaying player names * Camera facing UI * Off-screen spawning of enemies or other Game Objects * Indicator (arrow) for guiding the player towards off-screen Game Objects * Implementing Network Commands and Authority Transfer * Connection Events {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.coherence.io/1.0/get-started/prefab-setup.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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