Как спавнить объекты в unity

Spawning GameObjects

In Unity, you usually “spawn” (that is, create) new GameObjects with Instantiate() . However, in the multiplayer High Level API, the word “spawn” means something more specific. In the server-authoritative model of the HLAPI, to “spawn” a GameObject on the server means that the GameObject is created on clients connected to the server, and is managed by the spawning system.

Once the GameObject is spawned using this system, state updates are sent to clients whenever the GameObject changes on the server. When Unity destroys the GameObject on the server, it also destroys it on the clients. The server manages spawned GameObjects alongside all other networked GameObjects, so that if another client joins the game later, the server can spawn the GameObjects on that client. These spawned GameObjects have a unique network instance ID called “netId” that is the same on the server and clients for each GameObject. The unique network instance ID is used to route messages set across the network to GameObjects, and to identify GameObjects.

When the server spawns a GameObject with a Network Identity** **component, the GameObject spawned on the client has the same “state”. This means it is identical to the GameObject on the server; it has the same Transform, movement state, and (if NetworkTransform and SyncVars are used) synchronized variables. Therefore, client GameObjects are always up-to-date when Unity creates them. This avoids issues such as GameObjects spawning at the wrong initial location, then reappearing at their correct position when a state update arrives.

The Network Manager can only spawn and synchronize GameObjects from registered Prefabs, so you must register the specific GameObject Prefabs with the Network Manager that you want to be able to spawn during your game. The Network Manager will only accept GameObject Prefabs which have a Network Identity component attached, so you must make sure you add a Network Identity component to your Prefab before trying to register it with the Network Manager.

To register a Prefab with the Network Manager in the Editor, select the Network Manager GameObject, and in the Inspector, navigate to the Network Manager component. Click the triangle next to Spawn Info to open the settings, then under Registered Spawnable Prefabs, click the plus (+) button. Drag and drop Prefabs into the empty field to assign them to the list.

The Network Manager Inspector with the Spawn Info* foldout expanded, displaying three assigned Prefabs under Registered Spawnable Prefabs

Spawning without the Network Manager

For more advanced users, you may find that you want to register Prefabs and spawn GameObjects without using the NetworkManager component.

To spawn GameObjects without using the Network Manager, you can handle the Prefab registration yourself via script. Use the ClientScene.RegisterPrefab method to register Prefabs to the Network Manager.

Example: MyNetworkManager

In this example, you create an empty GameObject to act as the Network Manager, then create and attach the MyNetworkManager script (above) to that GameObject. Create a Prefab that has a Network Identity component attached to it, and drag that onto the treePrefab slot on the MyNetworkManager component in the Inspector. This ensures that when the server spawns the tree GameObject, it also creates the same kind of GameObject on the clients.

Registering Prefabs ensures that the Asset is loaded with the Scene, so that there is no stalling or loading time for creating the Asset.

However, for the script to work, you also need to add code for the server. Add this to the MyNetworkManager script:

The server does not need to register anything, as it knows what GameObject is being spawned (and the asset ID is sent in the spawn message). The client needs to be able to look up the GameObject, so it must be registered on the client.

When writing your own network manager, it’s important to make the client ready to receive state updates before calling the spawn command on the server, otherwise they won’t be sent. If you’re using Unity’s built-in Network Manager component, this happens automatically.

For more advanced uses, such as object pools or dynamically created Assets, you can use the ClientScene.RegisterSpawnHandler method, which allows callback functions to be registered for client-side spawning. See documentation on Custom Spawn Functions for an example of this.

If the GameObject has a network state like synchronized variables, then that state is synchronized with the spawn message. In the following example, this script is attached to the tree Prefab:

With this script attached, you can change the numLeaves variable and modify the SpawnTrees function to see it accurately reflected on the client:

Attach the Tree script to the treePrefab script created earlier to see this in action.

Constraints

A NetworkIdentity must be on the root GameObject of a spawnable Prefab. Without this, the Network Manager can’t register the Prefab.

NetworkBehaviour scripts must be on the same GameObject as the NetworkIdentity, not on child GameObjects

GameObject creation flow

The actual flow of internal operations that takes place for spawning GameObjects is:

Prefab with Network Identity component is registered as spawnable.

GameObject is instantiated from the Prefab on the server.

Game code sets initial values on the instance (note that 3D physics forces applied here do not take effect immediately).

NetworkServer.Spawn() is called with the instance.

The state of the SyncVars on the instance on the server are collected by calling OnSerialize() on Network Behaviour components.

A network message of type MsgType.ObjectSpawn is sent to connected clients that includes the SyncVar data.

OnStartServer() is called on the instance on the server, and isServer is set to true

Clients receive the ObjectSpawn message and create a new instance from the registered Prefab.

The SyncVar data is applied to the new instance on the client by calling OnDeserialize() on Network Behaviour components.

OnStartClient() is called on the instance on each client, and isClient is set to true

As gameplay progresses, changes to SyncVar values are automatically synchronized to clients. This continues until game ends.

NetworkServer.Destroy() is called on the instance on the server.

A network message of type MsgType.ObjectDestroy is sent to clients.

OnNetworkDestroy() is called on the instance on clients, then the instance is destroyed.

Player GameObjects

Player GameObjects in the HLAPI work slightly differently to non-player GameObjects. The flow for spawning player GameObjects with the Network Manager is:

Prefab with NetworkIdentity is registered as the PlayerPrefab

Client connects to the server

Client calls AddPlayer() , network message of type MsgType.AddPlayer is sent to the server

Server receives message and calls NetworkManager.OnServerAddPlayer()

GameObject is instantiated from the PlayerPrefab on the server

NetworkManager.AddPlayerForConnection() is called with the new player instance on the server

The player instance is spawned — you do not have to call NetworkServer.Spawn() for the player instance. The spawn message is sent to all clients like on a normal spawn.

A network message of type MsgType.Owner is sent to the client that added the player (only that client!)

The original client receives the network message

OnStartLocalPlayer() is called on the player instance on the original client, and isLocalPlayer is set to true

Note that OnStartLocalPlayer() is called after OnStartClient() , because it only happens when the ownership message arrives from the server after the player GameObject is spawned, so isLocalPlayer is not set in OnStartClient() .

Because OnStartLocalPlayer is only called for the client’s local player GameObject, it is a good place to perform initialization that should only be done for the local player. This could include enabling input processing, and enabling camera tracking for the player GameObject.

Spawning GameObjects with client authority

To spawn GameObjects and assign authority of those GameObjects to a particular client, use NetworkServer.SpawnWithClientAuthority, which takes as an argument the NetworkConnection of the client that is to be made the authority.

For these GameObjects, the property hasAuthority is true on the client with authority, and OnStartAuthority() is called on the client with authority. That client can issue commands for that GameObject. On other clients (and on the host), hasAuthority is false.

Objects spawned with client authority must have LocalPlayerAuthority set in their NetworkIdentity .

For example, the tree spawn example above can be modified to allow the tree to have client authority like this (note that we now need to pass in a NetworkConnection GameObject for the owning client’s connection):

The Tree script can now be modified to send a command to the server:

Note that you can’t just add the CmdMessageFromTree call into OnStartClient , because at that point the authority has not been set yet, so the call would fail.

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Как создать спавн объектов в Unity

Приветствую начинающих разработчиков! В данной статье мы научимся спавнить объекты на игровой сцене на примере 2D игры. Хотя он подойдёт и для 3д, но с минимальными изменениями в коде. Долго затягивать не будем, а приступим сразу к делу.

Для начала с помощью окна Hierarchy создадим пустой игровой объект(Create Empty), и назовём его SpawnArea. Этот объект будет являться нашим спавнером. Так же создайте префаб того объекта, который будет спавниться. Я создал свой префаб на основе обычного круглого 2д объекта (2D Object — Sprites — Circle). Назвал данный префаб Circle.

Спавнер вместе с префабом готов! Но чтобы этот спавнер работал, необходимо написать скрипт. С помощью окна Project создадим C# скрипт с названием Spawner, и заранее присвойте его нашему объекту с названием SpawnArea. В скрипт пропишите следующие строчки кода:

Давайте вкратце разберём код:

• В строке #5 мы создали переменную enemyPrefab, в которой будет храниться ссылка на наш префаб, который будет спавниться.
• В строках #7-8 мы создали две переменные отвечающие за время. В переменной timeSpawn хранится информация о том, сколько необходимо времени, для создания объекта на сцене. А в timer будет хранится сам таймер, по истечении которого будет создаваться объект на игровой сцене. Чуть позже вы поймёте разницу.
• В методе Start() мы в переменную timer заносим значение из timeSpawn.
• В методе Update() мы каждый кадр уменьшаем время нашего таймера timer, и как только оно закончится, то значение timer обновляется, а на игровой сцене, с помощью метода Instantiate() создаётся новый объект.

И в завершении необходимо настроить наш скрипт в окне Inspector:

• В поле Enemy Prefab перетащите префаб Вашего объекта Circle.
• В поле Time Spawn укажите время спавна для таймера. Я указал значение 2.

Готово! На этом этапе можете запустить свой проект, и убедиться, что всё работает успешно! Каждые 2 секунды происходит создание нового игрового объекта.

Спавнер созданный выше хорошо работает, но предлагаю его немного усовершенствовать, поскольку мне не нравятся в нём две вещи. Во-первых, все объекты создаются в одной точке, а хотелось бы, чтобы они создавались в случайной области в пределах определённого радиуса. А во-вторых, хотелось бы, чтобы создание объектов не производилось в тех случаях, когда в игре уже присутствует 10 объектов.

Предлагаю чуть чуть переписать наш код следующим образом:

Что же мы тут добавили? В строке #6 мы добавили переменную maxEnemy, которая отвечает за максимальное количество созданных объектов на игровой сцене. А в строке #11 в переменной distance храниться множитель для нашего радиуса спавнера, в пределах которого будут создаваться объекты. А сам радиус прописывается в строке #26 через Random.insideUnitCircle.

В строке #24 с помощью свойства childCount мы проверяем, сколько у нас имеется созданных объектов. И если их число меньше 10, то происходит создание нового объекта, иначе — ничего не делать.

Наш скрипт готов! Теперь запустим его, и увидим следующую картину. Каждые 2 секунды в нашем проекте создаётся по одному объекту, в случайной точке, радиусом в 3, от нашего спавнера. И как только было создано 10 объектов, спавнер прекращает свою работу.

Но и этот спавн можно усовершенствовать. Мы можем спавнить не один и тот же объект, а разные объекты, которые будут спавниться случайным образом. Но это уже совсем другая история. О том, как это можно реализовать, можете прочитать наш отдельный гайд, под названием «Создаём рандомный спавн объектов».

На этом наш гайд подошёл к концу. Если остались вопросы, задавайте их в комментариях. А так же не забывайте ставить свои лайки.

Unity Instantiate prefab C# tutorial for beginners

You can use Unity instantiate function to spawn prefabs or Gameobjects at any point in the game world. Unity requires the game object to be a prefab or available in scene hierarchy in order to spawn it.

In this post, we will see how you can spawn objects in Unity using instantiate function in your C# script and where not to use Unity Instantiate.

What is Unity prefab?

Before we jump into Unity instantiate, you must know what a prefab is?

A prefab is a game object which has already been customized to be deployed in a game scene. For example, if you have a character in your scene, you can set the position, rotation, scale, and add other components required and move it to the project window. You can use this character in your game at a later stage. Any game object in which you add these required components and keep it ready in the Unity resources folder for deployment is called a prefab in Unity.

Instantiating a prefab in Unity

Now if you hit play, the prefab will be instantiated on to your game scene at start. Unity by default names the gameobject as a clone of your prefab. So if your prefab name is Friend Cube then Unity will name it Friend Cube(Clone).

Instantiate prefab as a child of another object

You can do this by instantiating your prefab as a Gameobject and then assigning the parent. This method can be used to instantiate an UI prefab also. You just need to make sure that the parent is inside the canvas.

Instantiate prefab in Unity by name

You can reference the prefab game object and load it from the resource folder directly using

The prefab you are referencing should be inside the resource folder. This is not a good practice as its more performance extensive.

Giving a Custom name to the Instantiated prefab

By default, any game object that is instantiated in Unity is given the name “Prefab_name(Clone)”. The name of the object doesn’t make any difference unless you want to access it by a custom name.

If that is the case then you can assign the instantiated prefab to a game object and then set a name to the game object.

Here is the sample code

When and when not to use Unity instantiate

Instantiate is really useful but when using it to spawn multiple objects can fill the memory and affect game performance. Let’s see what are the ideal conditions when you can use instantiate.

1. Spawn single characters that stay throughout the game like the player Gameobject.
2. Objects that are limited in number like ammo, power-ups, etc. which are destroyed later.
3. For effects on objects like a fire that dies down after a few seconds.

Remember to destroy the object after it’s no longer needed otherwise it will add up the game memory and cause the game to freeze. So, it’s better not to use instantiate when multiple spawn is required. In that case, you can create an object pool and make them active when required.

For example, you can add a bullet Gameobject to the scene and set it as inactive. When the gun fires set the Vector3 position of the bullet to the front of the gun and make the bullet object active. When the bullet hits a surface then deactivate it rather than destroying it. This will reduce the memory load caused by the instantiate function. You can learn about colliders to know when to deactivate the Gameobject.

Check out the Unity asset below for efficient use of object pooling and to improve your game’s performance.

Instantiating a Projectile in Unity

The only difference between instantiating a game object and instantiating a projectile is, you need to add a force to the instantiate projectile so that it will move. The best way is to create an empty object and place it on the corner of your main object. For example, if you making a rocket projectile for a rocket launcher then you need to place this empty game object at the tip of the rocket launcher.

Create an Empty gameobject and call it Projectile_Spawner.

Add a Script to it called SpawnProjectile.

Create a projectile prefab with a Rigidbody component. For this example, we will be adding force to the projectile to move it. You can create any prefab depending on your game’s requirement.

Add the below script to instantiate the projectile and add force to it.

Assign your projectile to the script and you are ready to launch a projectile.

Unity Instantiate trick that no one teaches you

As in the above example of projectile. To access the Rigidbody of the spawned gameobject, we are instantiating the gameobject, assigning it to another gameobject and using the get component method to get the rigidbody. Then we apply force on it.

There are is a simpler way. You can instantiate the component rather than the game object. This way you need not use the get component function and Unity instantiates the game object by default. This is more performance efficient than the conventional way.

Here is how the above projectile script can be simplified.

How to Instantiate at random positions in Unity

To instantiate game objects at random positions, you need to generate random numbers and create a vector 3 with it. We will keep the y value fixed and randomize the x and z values.

Let’s use random.range to generate these values. The random range will include the minimum value and exclude the maximum value.

Instantiate using visual scripting in Unity

If you are not comfortable using scripting in Unity then you can also use visual scripting to instantiate a game object.

Creating a flow graph

1. Create a new empty object in the hierarchy window.
2. Name it as instantiate_graph.
3. Go to inspector window and click add component.
4. Add a Script machine component.
5. Click new to create a new graph.
6. Name it as instantiate_example.

Creating the logic

We are going to instantiate a prefab called my_prefab after 5 seconds of game start.