Instantiate creates multiple clones in Unity

Question

I have the following code:

public Rigidbody2D ball;
Vector2 sp = new Vector2(0f, 2.1f);

void Update() {
    if (Input.GetKeyDown("w")) {
        SpawnBall();           
        DestroyBall();
    }
}
void SpawnBall()
{
    Instantiate(ball, sp, transform.rotation);
}

void DestroyBall()
{
    if (ball.transform.position.y >= -5.7f)
    {
        Destroy(ball);
    }
}

and the code is supposed to generate a new ball every time when "w" is pressed, but for some reason it creates multiple clones and it crashes the engine. How can I create a single clone only?

And also the destroy method doesn't do anything, although it should remove the clone when it passes -5.7 on the y-axis.

Thanks in advance

Answer 1

Create a new script named "SpawnRigidbody" and copy and paste the below code.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SpawnRigidbody : MonoBehaviour 
{

    public Rigidbody2D ball;
    Vector2 sp = new Vector2(0f, 2.1f);

    void Update() 
    {
        if (Input.GetKeyDown("w")) {
            SpawnBall();
        }
    }

    void SpawnBall()
    {
        Debug.Log ("spawn");
        GameObject go = Instantiate(ball, sp, transform.rotation).gameObject;
        go.AddComponent<DestroyAfterPosition> ();
    }
}

Now create another script named "DestroyAfterPosition" and copy and paste the below code.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DestroyAfterPosition : MonoBehaviour 
{

    void Update ()
    {
        if (transform.position.y <= -5.7f)
        {
            Destroy(gameObject);
        }
    }
}

Create an empty game object and attach the SpawnRigidbody and then assign your ball in the inspector.

Hope this help you.