Bdtjtk

I am working on a AR project, where the virtual objects will be shown/hide in the scene based on information found in a text file. The text files will be updated from an external service. So I need to read the file on a frequent interval and update the scene. As a result I only have the Camera object and I am rendering the scene in OnPreCull() method.

The text files contain many objects but not all the objects are within the scene at any instance of time. I was looking for a way to render only those objects that are within the scene.

Will creating and placing the gameobjects in the OnPreCull() method crate any performance issue?

Will creating and placing the gameobjects in the OnPreCull() method crate any performance issue?

Yes absolutely ... so would it if you do it in Update or any other repeatedly called method.

Instead you should rather Instantiate objects in Awake and only activate or deactivate them.

Let's say you have 3 objects A, B and C than I would make a kind of controller class that looks like

public class ObjectsController : MonoBehaviour

{

    // Define in which intervals the file should be read/ the scene should be updated

    public float updateInterval;



    // Prefabs or simply objects that are already in the Scene

    public GameObject A;

    public GameObject B;

    public GameObject C;

    /* Etc ... */



    // Here you map the names from your textile to according object in the scene

    private Dictionary<string, GameObject> gameObjects = new Dictionary<string, gameObjects>();



    private void Awake ()

    {

        // if you use Prefabs than instantiate your objects here; otherwise you can skip this step

        var a = Instantiate(A);

        /* Etc... */



        // Fill the dictionary

        gameObjects.Add(nameOfAInFile, a);



        // OR if you use already instantiated references instead

        gameObjects.Add(nameOfAInFile, A);

    }

}



private void Start()

{

    // Start the file reader

    StartCoroutine (ReadFileRepeatedly());

}



// Read file in intervals

private IEnumerator ReadFileRepeatedly ()

{

    while(true)

    {

        //ToDo Here read the file



        //Maybe even asynchronous?

        // while(!xy.done) yield return null;



        // Now it depends how your textile works but you can run through 

        // the dictionary and decide for each object if you want to show or hide it

        foreach(var kvp in gameObjects)

        {

            bool active = someConditionDependingOnTheFile;



            kvp.value.SetActive(active);



            // And e.g. position it only if active

            if (active)

            {

                kvp.value.transform.position = positionFromFile;

            }

        }



        // Wait for updateInterval and repeat

        yield return new WaitForSeconds (updateInterval);

    }

}

If you have multiple instances of the same prefab you also should have a look at Object Pooling

I'd recommend adding each of the game objects to a registry and the switching them on or off (dis/enable SetActive) via the registry class's Update() cycle.

One Update() process to retrieve and handle the server file, another Update() process to dis/enable objects. Might sound oversimplified however it's the fastest way I think of getting the result.

Good Luck!