Instantiated Prefab no Rigidbody2D on Update function

Questions & Answers
1

Hey there,

I have the following situation:

I got a GameplayManager script like this:

public class GameplayManager : MonoBehaviour
{
    public Transform spawnPoint1;
	public Rigidbody2D player;

	void Start()
	{
		Instantiate (player, spawnPoint1.position, spawnPoint1.rotation);
	}

        ....
}

There is a prefab assigned to the “player” variable there is an empty gameobject assigned to the spawnPoint1 variable.

This script-component(GameplayManager) is attached to the camera component.

On my “player” prefab i assigned a new script component “PlayerManager”:

public class PlayerManager : MonoBehaviour
{
	Rigidbody2D rb2d;

	void Start()
	{
		rb2d = GetComponent<Rigidbody2D> ();
	}

	void Update()
	{
		
	}

	public void Jump()
	{
		rb2d.AddForce (new Vector2 (rb2d.velocity.x, 500f));
	}

    ...
}

Next i added a Button to my canvas and assigned a Event Trigger:
Value: “Player” Prefab
Select: PlayerManager.Jump()

When i press the button in the game, no force is applied to the rigidbody of the player prefab.

I simply dont know why…any help or advices?

Thansks and Greetings

2

You should understand the difference between a prefab and it’s instance. A prefab is just a prototype that exists in a memory but not in a scene. An instance is a copy built from this prototype and placed into the scene.

So if you are calling a method on a prefab you are not calling a method on an actual instance you’ve created using Instantiate().

To call a method on the instance of the prefab you need to store a reference to this copy an use it like reference.method();

Try saving a reference when you instantiate the prefab in GameplayManager and assign it’s method to the button:

[SerializeField]
private UnityEngine.UI.Button button;

void Start()
{
	//saving reference to a copy created
	GameObject instance = Instantiate (player, spawnPoint1.position, spawnPoint1.rotation) as GameObject;
		
	//getting PlayerManager on this copy
	PlayerManager pManager = instance.GetComponent<PlayerManager>();
		
	//if there is a PlayerManager on this copy
	if(pManager != null)
		//assign instance's method to the button onClick delegate
		button.onClick.AddListener(pManager.Jump);
}