Spawn Objects

ObjectNet allows to spawn objects over network, when those objects are spawned all network peers will be notified to spawn the same object.

The script does not need to be inheriting from Network Behaviour for it to work, you can spawn and despawn on any Unity C# scripits.

Spawning on the Server

On the server (or host), you can spawn network objects using Unity's standard Instantiate() method. ObjectNet's built-in detection system will automatically recognize when a NetworkObject is created and synchronize it across all connected clients. This makes it easy to use Unity’s native object creation workflow for networked objects.

Alternatively, you can use ObjectNet's dedicated NetworkGameObject.NetworkInstantiate()method for similar results.

// Using Unity's Instantiate method
GameObject.Instantiate(this.prefabToSpawn, this.spawnPosition, Quaternion.identity);

// OR using ObjectNet's NetworkGameObject.Instantiate
NetworkGameObject.NetworkInstantiate(this.prefabToSpawn, this.spawnPosition, Quaternion.identity);

Both methods will ensure the object is created on all clients and properly synchronized.

Spawning on Clients

On clients, ObjectNet's automatic detection system does not apply. This means that simply using Unity’s Instantiate method will only create the object locally and will not synchronize it with other clients.

To spawn an object across all clients from a non-server instance, you must use NetworkGameObject.NetworkInstantiate(). This explicitly informs the server to handle the object creation and propagate it to all other connected clients.

// Using ObjectNet to spawn the object on all clients
NetworkGameObject.NetworkInstantiate(this.prefabToSpawn, this.spawnPosition, Quaternion.identity);

This ensures the object is properly created and synchronized across the network, regardless of whether the request originated from the server or a client.

Retrieveing GameObject Reference

When spawning a network object using ObjectNet, you can retrieve a reference to the instantiated GameObject. ObjectNet uses asynchronous operations to ensure the object is fully synchronized across the network before providing the reference.

You can use the await keyword with the NetworkGameObject.Instantiate method to get the spawned object. This guarantees that the reference is ready and fully initialized for use.

public async void SpawnGameObjectExample()//note the method need to be async
{
   // Spawn the object and retrieve its reference asynchronously
   GameObject spawnedObject = await NetworkGameObject.Instantiate(this.prefabToSpawn, this.spawnPosition, Quaternion.identity);
}

Using async/await with ObjectNet's NetworkGameObject.Instantiate ensures that your code is efficient, reliable, and synchronized across the network.

Note: The instance returned from await may require one additional frame before network-related features are fully initialized.

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FAQ:

Why doesn’t the client have control over the object it spawns?

By default, any NetworkObject created in the network is automatically owned by the host. This means the client that spawned the object does not have authority over it unless specified otherwise.

To give control to the client that spawns the object, you have two options:

• Set the Access Level to Client-Only This will ensure that the client automatically gains ownership of the objects that they instantiate.

NetworkObjects with ClientOnly access level do not support ownership transfer. Once assigned, ownership cannot be changed.

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• Alternatively, the client can manually request ownership of the spawned object by calling TakeControl() for example:

  GameObject _spawnedObject = await NetworkGameObject.Instantiate(this.prefabToSpawn, this.spawnPosition, Quaternion.identity);
  _spawnedObject.GetComponent<NetworkObject>().TakeControl();

  This allows dynamic ownership transfer after the object has been instantiated see Dynamic Ownership Transfer for more details on this topic.