How to trigger scene transition on collision for runtime instantiated object in Unity?

Question

I'm making a game on unity where the user selects a character and the character spawns into the game world. The world consists of different doors. I want to add a transition animation (just a regular fade) between scenes in the game world but because the character is instantiated during runtime, I'm not sure how to attach the animator to the character. I also want the animation to trigger upon collision of the player with a door. I know how to create the animation clips and the animator but I need help on knowing when and how to attach the animator to an object that's going to be instantiated during runtime. Will I attach the animator in OnCollisionEnter() function? If so, how do I reference that animator through code?

Here is my code for OnCollisionEnter in a script that is attached to the player during runtime. (this works fine)

private void OnCollisionEnter(Collision collision)
    {
        GameObject door = collision.gameObject;
        
        if (door.CompareTag("ExitDoor"))
            SceneManager.LoadScene(0); // spawn back at main lobby
        else if (door.CompareTag("RoomDoor"))
        {
            GameObject Room = door.transform.parent.gameObject;
            if (Room.name.Equals("Room1Door"))
                SceneManager.LoadScene(1); // go to first room
            if (Room.name.Equals("Room2Door"))
                SceneManager.LoadScene(2); // go to second room
            if (Room.name.Equals("Room3Door"))
                SceneManager.LoadScene(3); // go to third room
        }
    }

And here is the script of instantiating the player during runtime when the scene is loaded (this is in another script)

public GameObject InstantiatePlayer()
    {
        characterIndex = PlayerPrefs.GetInt(playerprefkey);
        selectedChar = characters[characterIndex];
        selectedChar.tag = "Player";
        selectedChar.AddComponent<MoveRooms>(); //attaches the script where OnCollisionEnter is
        return Instantiate(selectedChar, spawnPoint.transform.position, spawnPoint.transform.rotation);
    }

Answer 1

to get the Animator, you can do this if the script is attached

Animator anim;

void Start()
{
     anim = gameObject.GetComponent<Animator>();
}

else if it is not attached you can try something like this

GameObject object;
Animator anim;
    
    void Start()
    {
         object = GameObject.Find("objectsname");
         anim = object.GetComponent<Animator>();
    }

For further details how to use Animator

https://docs.unity3d.com/ScriptReference/Animator.html

https://docs.unity3d.com/ScriptReference/Animator.Play.html https://docs.unity3d.com/ScriptReference/Animator.SetTrigger.html

As for a transition , you can try to use Caroutines. What Caroutines are is it executes a piece of code 'on the side' whie the other codes continue. It can be used to "wait" for a few seconds (or more). Its very useful and you can do alot with it.

some examplee

public class ExampleClass : MonoBehaviour
{
    void Start()
    {

        // Start function as a coroutine.    
        StartCoroutine(waitForSeconds);

    }

    private IEnumerator waitForSeconds()
    {
        //do something
        yield return new WaitForSeconds(1f); // the number is in seconds. 
        //do something else
    }
}

https://docs.unity3d.com/ScriptReference/Coroutine.html