problem with targeting system with raycast;

Questions & Answers
1

HI I’m new to programming and I’m trying to join a couple of scripts. the raycast part of the script seems to return an nullreferenceexception and I don’t find the solution. The code is :

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class TargettingSystem : MonoBehaviour {


	public List <Transform> targets;
	public Transform selectedUnit;
	void Start()
	{
		targets = new List <Transform> ();
		AddAllEnemies ();
		selectedUnit = null;
	}
	void Update () 
	{
		if (Input.GetKeyDown (KeyCode.Tab)) 
		{
			targetEnemy ();
		}
		if (Input.GetMouseButtonDown(0))  
		{
			SelectTarget ();
		}
	}
	void SelectTarget()
	{
		
		Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
		RaycastHit hit;
		if (Physics.Raycast (ray, out hit, 10000)) 
		{
			if (hit.transform.tag == "Enemy") 
			{
				selectedUnit = hit.transform.gameObject.transform;
			}
		}
	}
	public void AddAllEnemies()
	{
		GameObject[] go = GameObject.FindGameObjectsWithTag ("Enemy");
		foreach (GameObject enemy in go)
			AddTarget (enemy.transform);

	}
	public void AddTarget (Transform enemy)
	{
		targets.Add(enemy);
	}
	private void targetEnemy()
	{
		selectedUnit = targets [0];
	}

}

2

Because the error takes place in line 29:

Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);

It could be a ray issue, a camera issue or an input issue.

Ray ray (should be a ray) > ScreenPointToRay() (That’s a ray).

Camera.main > Should be a camera. Are you sure about this? Maybe try to assign the camera to a variable to see if there are any problems there. I saw something in this post:

Maybe you have a script called “Camera” that is messing things up?

Input.mousePosition, cant see anything wrong there. The combination of ScreenPointToRay(Input.mousePosition) is used a lot so I don’t see why there would be a problem there.

Try to mess around with the camera, maybe that’s where the problem is. Because when your “Camera.main” isn’t a real camera, you cant call a method like ScreenPointToRay on it, and it will return a error.