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81 lines
3.1 KiB
Markdown
81 lines
3.1 KiB
Markdown
# SyncVars
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[](https://www.youtube.com/watch?v=T7AoozedYfI&list=PLkx8oFug638oBYF5EOwsSS-gOVBXj1dkP&index=5)
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SyncVars are properties of classes that inherit from NetworkBehaviour, which are synchronized from the server to clients. When a game object is spawned, or a new player joins a game in progress, they are sent the latest state of all SyncVars on networked objects that are visible to them. Use the `SyncVar` custom attribute to specify which variables in your script you want to synchronize.
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The state of SyncVars is applied to game objects on clients before `OnStartClient()` is called, so the state of the object is always up-to-date inside `OnStartClient()`.
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SyncVars can use any [type supported by Mirror](../DataTypes.md). You can have up to 64 SyncVars on a single NetworkBehaviour script, including SyncLists (see next section, below).
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The server automatically sends SyncVar updates when the value of a SyncVar changes, so you do not need to track when they change or send information about the changes yourself.
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> The [SyncVar hook](SyncVarHook.md) attribute can be used to specify a method to be called when the SyncVar changes value on the client.
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## SyncVar Example
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Let's say we have a networked object with a script called Enemy:
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``` cs
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public class Enemy : NetworkBehaviour
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{
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[SyncVar]
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public int health = 100;
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void OnMouseUp()
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{
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NetworkIdentity ni = NetworkClient.connection.identity;
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PlayerController pc = ni.GetComponent<PlayerController>();
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pc.currentTarget = gameObject;
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}
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}
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```
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The `PlayerController` might look like this:
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``` cs
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public class PlayerController : NetworkBehaviour
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{
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public GameObject currentTarget;
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void Update()
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{
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if (isLocalPlayer)
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if (currentTarget != null)
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if (currentTarget.tag == "Enemy")
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if (Input.GetKeyDown(KeyCode.X))
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CmdShoot(currentTarget);
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}
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[Command]
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public void CmdShoot(GameObject enemy)
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{
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// Do your own shot validation here because this runs on the server
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enemy.GetComponent<Enemy>().health -= 5;
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}
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}
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```
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In this example, when a Player clicks on an Enemy, the networked enemy game object is assigned to `PlayerController.currentTarget`. When the player presses X, with a correct target selected, that target is passed through a Command, which runs on the server, to decrement the `health` SyncVar. All clients will be updated with that new value. You can then have a UI on the enemy to show the current value.
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## Class inheritance
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SyncVars work with class inheritance. Consider this example:
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```cs
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class Pet : NetworkBehaviour
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{
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[SyncVar]
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String name;
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}
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class Cat : Pet
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{
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[SyncVar]
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public Color32 color;
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}
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```
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You can attach the Cat component to your cat prefab, and it will synchronize both it's `name` and `color`.
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> **Warning** Both `Cat` and `Pet` should be in the same assembly. If they are in separate assemblies, make sure not to change `name` from inside `Cat` directly, add a method to `Pet` instead.
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