How to activate an object only when it's within the camera view

Question

I want to toggle an object's active state using the camera view:

• when the object leaves the view it deactivates
• when the object enters the camera's view it activates

I'm using this to control the activity of objects in a carousel like this

I did this with a coroutine, but in my project the fps is falling a lot because of the coroutine.

I've already used OnBecameVisible and isVisible but that's not it since they only work with a renderer.

    public void next() {
        StartCoroutine(On(waitnext));
    }

    IEnumerator On(float waitnext) {
        yield return new WaitForSeconds(waitnext);
        myArray[Selecao].SetActive(false);
        Selecao++;
        if(Selecao > myArray.Length - 1) {
            Selecao = 0;
        }
        yield return new WaitForSeconds(waitnext);
        myArray[Selecao].SetActive(true);
    }

    public void previous() {
        StartCoroutine(On2(waitprevious));
    }

    IEnumerator On2(float waitprevious) {
        yield return new WaitForSeconds(waitprevious);
        myArray[Selecao].SetActive(false);
        Selecao--;
        if(Selecao < 0) {
            Selecao = myArray.Length - 1;
        }
        yield return new WaitForSeconds(waitprevious);
        myArray[Selecao].SetActive(true);
    }

Answer 1

You can achieve this by adding colliders to your object and camera.

• preferably set the camera collider isTrigger on if the object is a rigid body.
• You can use tags, layers and game object name to filter which object you want to operate on.

Here is the code:

[RequireComponent(typeof(Collider))]
public class FrustomColliderDetector : MonoBehaviour
{
    //Gets called when it enters the camera collider
    private void OnCollisionEnter(Collision other) {
        if(other.gameObject.tag == "object-tag")
            other.gameObject.SetActive(true);
    }
    //Gets called when it leaves the camera collider
    private void OnCollisionExit(Collision other) {
        if(other.gameObject.tag == "object-tag")    
        other.gameObject.SetActive(false);
    }

}