Selection Management c#

Unity Engine
1

Here I have been trying to create a selection management so that at any given time there will be only one gameobject selected or highlighted. I have done my utmost and here I have put the script. The thing is, i cant seem to alternate selections and I often get a “NullReferene”. The script is partly working and partly not. Can you help me out? I need to know how to get thing done.

using UnityEngine;
using System.Collections;

public class MouseControl1 : MonoBehaviour {
    //This scripts handles the actions performed by the mouse

    public GameObject currentlyselected;
    public bool selected = false;
    public RaycastHit hit;
 
    public void Start ()
    {

    }

    public void Update()
    {
        MouseController();
    }

    //This funcition controls the actions performed by the mouse
    public void MouseController()
    { 
        //if the left mouse button is down
        if(Input.GetMouseButtonDown(0))
        {
            //Player pressed the mousebutton
            Debug.Log ("Player pressed the mousebutton.");
            //cast a ray into the scene to detect objects
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            if(Physics.Raycast(ray, out hit, Mathf.Infinity))
            {
                //print the name of the object the ray collided
                Debug.Log(hit.transform.gameObject.name);
            }

            //if the ray hits a player
            if(hit.transform.gameObject.tag == "Player")
            {
                currentlyselected = hit.transform.gameObject;
                Select();
                Debug.Log(1);
            } else {
                if(selected == true)
                {
                    Deselect();
                    currentlyselected = hit.transform.gameObject;
                    Select();
                    Debug.Log(2);
                }
            }

            //if the ray doesn't hit the player and the object is selected
            if(hit.transform.gameObject.tag != "Player" && selected == true)
            {
                Deselect();
                Debug.Log(3);
            } else {
                if(selected != true)
                {
                    Debug.Log("There was nothing there.");
                    Debug.Log(4);
                }
            }
        }
    }

    public void Select()
    {
        currentlyselected.transform.FindChild("Blob Light Projector").gameObject.SetActive(true);
        selected = true;
    }

    public void Deselect()
    {
        currentlyselected.transform.FindChild("Blob Light Projector").gameObject.SetActive(false);
        currentlyselected = null;
        selected = false;
    }

}
2

What is line number where you gon an error?

I see couple of danger strokes:

currentlyselected.transform.FindChild("Blob Light Projector").gameObject.SetActive(true)

It will give you an NullRef exception in case when “Blob Light Projector” object is not exist.
This is more safety code style:

var go = currentlyselected.transform.FindChild("Blob Light Projector");
if(go!= null)
   go.gameObject.SetActive(true);
else
   Debug.Log("'Blob Light Projector' was not found among children of '"+currentlyselected.Name+"'");
1 Like
3

I’m thinking you have to put the lines 38 to 65 also into the if clause which starts at line 32. It should look like this:

            if(Physics.Raycast(ray, out hit, Mathf.Infinity))
            {
                //print the name of the object the ray collided
                Debug.Log(hit.transform.gameObject.name);
                //if the ray hits a player
                if(hit.transform.gameObject.tag == "Player")
                {
                    currentlyselected = hit.transform.gameObject;
                    Select();
                    Debug.Log(1);
                } else {
                    if(selected == true)
                    {
                        Deselect();
                        currentlyselected = hit.transform.gameObject;
                        Select();
                        Debug.Log(2);
                    }
                }
    
                //if the ray doesn't hit the player and the object is selected
                if(hit.transform.gameObject.tag != "Player" && selected == true)
                {
                    Deselect();
                    Debug.Log(3);
                } else {
                    if(selected != true)
                    {
                        Debug.Log("There was nothing there.");
                        Debug.Log(4);
                    }
                }
            }

Otherwise you check in your if statements for the tags of the gameobjects, but the ray hasn’t hit something.

1 Like
4

Well that does make sense but I think I will try what patico recommended. After posting this question in the forum even his solution occurred to me.

5

Cheers mate! I will give this a try…