Deselect object when another instance is selected

Questions & Answers
1

I have seen this same question asked a couple times but I was unable to get it to work for my setup after reading through several solutions.

Relevant: C#, 2D
My problem is I have a couple instances of a prefab that are selectable by mouse click. I want it so that when I select one of these objects, the previously selected object is de-selected. Currently I am attempting to do this with a static bool on the class that trips a deselect function, and using the OnMouseDown function to protect that certain instance from the deselect function. Here is my code: (Apologies for sloppy formatting)

public class spawnScript : MonoBehaviour {


	public bool selected;		
	public bool notSelected = true;

    //static bool for tripping deselect function
	public static bool clear;


	void Update () {

		//if clear is tripped
		if (clear) {
			//run deslect method
			clearSelection ();

			//reset clear
			clear = false;
		}

	}
	
	public void OnMouseDown(){
		//protect this gameObject from being cleared
		notSelected = false;

		//trips the clear boolean on all instances
		spawnScript.clear = true;

		//select this gameObject
		selected = true;
	}

	public void OnMouseUp(){
		//sets it up to be clearable in the future
		notSelected = true;
	}
	
	
	//clears selection
	public void clearSelection(){
			//Instances not clicked are deselected
			if (notSelected) {
				selected = false;
			}
		}
	}

currently, the deselect function isn’t tripping correctly. I am pretty new to all this, and suspect my problem is using a static bool and then manipulating that bool within the same class. Almost positive this is the issue, but I’ve tried so many things that I kind of lost myself and fear I am trying the same things over and over.

I tried several raycast2D methods instead and couldn’t get it to work… Most likely I need to change my logic to a single SelectManager class that these prefabs reference instead, but I haven’t tried that yet. Any advice to make this script work, or, advice pointing me in the best direction (retry raycasts, try a SelectManager, etc.) will be greatly appreciated.

3

Here is how I might approach your original solution using a static variable:

using UnityEngine;
using System.Collections;

public class spawnScript : MonoBehaviour {
	
	static private Transform trSelect = null; 
	private bool selected = false;

	void Update () {
	
		if (selected && transform != trSelect) {
			selected = false;
		}
		
	}
	
	public void OnMouseDown(){
		selected = true;
		trSelect = transform;
	}
}
2

I got something to work, not using static variables. I instead have the following script attached to a Player gameobject that manages the game. Here is the script for selection

public void Update(){
       //On the units, I have an OnMouseDown that changes the tag to SelectMe
	GameObject newSlot = GameObject.FindGameObjectWithTag ("SelectMe");

	if (newSlot != null) {
        //search for and store the Previously Selected Unit
	    GameObject oldSlot = GameObject.FindGameObjectWithTag("Selected");

        //The last clicked unit becomes selected
	    spawnScript towerSelect = newSlot.GetComponent<spawnScript> ();
	    towerSelect.selected = true;

	    //Then becomes the latest Selected unit
        newSlot.tag = "Selected";
       
	    //The previous Selected unit becomes de-selected
	    spawnScript towerDeselect = oldSlot.GetComponent<spawnScript>();
	    towerDeselect.selected = false;

	    //and is set back to Untagged
        oldSlot.tag = "Untagged";
	}
}

I have tested this and it works perfect. The obvious set back here is running several FindGameObjectWithTags. I know this is bad for overall performance, but for my current needs and Prototyping, it works. If you agree please upvote this answer I can use some reputation!

4

I tend to use a manager for this. The manager sends a message to each GameObject when it is selected and when it is deselected. This type of setup is very easily extendable for multiple selectable GameObjects.

Pseudo code:

public class SelectManager : MonoBehaviour {

    public GameObject selectedObject {get; private set;}

    public void ChangeSelection (GameObject newSelection){
        if(selectedObject){
            selectedObject.SendMessage ("Deselect");
        }
        selectedObject = newSelection;
        selectedObject.SendMessage ("Select");
    }    
}

You can call ChangeSelection from a raycast or from OnMouseUp on the individual GameObjects. You should also consider the case where the selectedObject is destroyed while selected. I typically handle this by reverting the selection to the SelectManager if nothing else is selected.