Raycast 2D hits sprite with collider, but returns error when not hitting any collider

Questions & Answers
1

Hi everyone,

I’ve been circling around this problem, and I can’t find a solution anywhere.

I basically want to do a raycast2D from a touch, and interact with a button (in this particular case, a sprite, with a collider2D component).

I can get the raycast to work, but IF I don’t hit the button (anywhere else on screen) I always get an error message saying:

“NullReferenceException: Object
reference not set to an instance of an
object Touch_Controls.Update () (at
Assets/Scripts/Touch_Controls.cs:24)”

For some reason, I can’t get the raycast to simply ignore the fact that it’s not hitting anything.

I’m guessing this is probably something very simple I’m just overlooking, but it’s infuriating. Please help me! :expressionless:

Here’s my code:

using UnityEngine;
using System.Collections;

public class Touch_Controls : MonoBehaviour
{
	public GUIText tapText;
	public Game_Speed gameSpeedScript;

	// Update is called once per frame
	void Update ()
	{
		foreach (Touch touch in Input.touches)
		{
			RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(touch.position),Vector2.zero);

			if (hit.collider.tag == "Button")
			{
				Debug.Log("Button Activated");
			}
			else
			{
				Debug.Log("Nothing hit");
			}
		}

	}
}
2

Your problem is here:

  if (hit.collider.tag == "Button")

When a Raycast() does not hit anything, the collider of the RaycastHit2D will be null. Trying to get ‘.tag’ from a null collider will generate the exception. Change the line to something like:

  if ((hit.collider != null) && (hit.collider.tag == "Button))
3

you must check if the hit.collider is not null first:

	if (hit.collider != null && hit.collider.tag == "Button"){
		Debug.Log("Button Activated");
	}

you can check the usage of Physics2D.Raycast here: