Detect when no longer hittting an object with raycast

Unity Engine
1

Im trying to make a sort of gui system where i only display an enemies stats (hp etc.) when im targetting them with the crosshair. To target them i use a raycast and i have it display the info when i hit them with it. But i need a way to tell the script that im no longer hitting the enemy with that raycast so it can disable the gui. Can anyone help?

Current code:

function LookRay()
{
	var direction = transform.TransformDirection(Vector3.forward);
	var ray = Camera.main.ScreenPointToRay(Vector3(Screen.width/2, Screen.height/2,0));
	var hit : RaycastHit;
	
	if(Physics.Raycast(ray, hit, range))
	{
		Debug.DrawLine(ray.origin, hit.point, Color.red);
		if(hit.rigidbody)
		{
			hit.transform.SendMessage("EnableGUI", SendMessageOptions.DontRequireReceiver);
		}
		
	}
	
}
1 Like
2 
#pragma strict

var hittingTarget : boolean;

function Update () {

	if(!hit.rigidbody){
		hittingTarget = false;
	}
}

Just put a ! in front of something if you want to check if something is not true, or if it’s not hitting something… keyword “not”.

3

Note: Untested.

var objectPreviouslyHit;

function LookRay()
{
    // cast a ray into our scene from where our crosshair is looking to see if we are currently hitting
    // anything at all
    var direction = transform.TransformDirection(Vector3.forward);
    var ray = Camera.main.ScreenPointToRay(Vector3(Screen.width/2, Screen.height/2,0));
    var hit : RaycastHit;
    
    // when the ray hits nothing it means our crosshair isn't over anything of importance
    // we want to early out and perform no further tests, but we need to ensure we inform
    // the previously selected object, if there is one, to turn off the GUI.
    if(Physics.Raycast(ray, hit, range)==false)
    {
        if (objectPreviouslyHit != null)
        {
            objectPreviouslyHit.transform.SendMessage("DisableGUI", SendMessageOptions.DontRequireReceiver);
            objectPreviouslyHit = null;
        }

        return;
    }

    // when the ray hits something of interest, confirm that it is a new object, and if 
    // it is, tell the previously selected object, if one was selected, to turn off the GUI.
    if ((objectPreviouslyHit != hit)  (objectPreviouslyHit != null))
    {
        objectPreviouslyHit.transform.SendMessage("DisableGUI", SendMessageOptions.DontRequireReceiver);
        objectPreviouslyHit = null;
    }
    
    // display a debug line to let the user understand what is going on with the ray cast
    Debug.DrawLine(ray.origin, hit.point, Color.red);
    // our ray may have hit something, but that "something" might not have a rigid body attached
    // so test for that, and if no rigid body is found, early out because we don't need to do
    // anything else
    if(hit.rigidbody == null)
    {
        return;
    }

    // our ray hit an object of interest, let that object of interest know that
    // the GUI should be enabled.
    hit.transform.SendMessage("EnableGUI", SendMessageOptions.DontRequireReceiver);

    // store the object our ray hit for future use so that when we come back through
    // we can check to see if we are hovering over the same object and thus don't
    // accidentally re-enable the GUI again.
    // we also store the object to detect switching between two objects or deselecting 
    // the current object.
    objectPreviouslyHit = hit;
}
4

Hey thanks man it worked. Only difference is objectPreviouslyHit must be a rigidbody and set to hit.rigidbody otherwise works like a charm.

Here is the code for anyone else who wants to use it.

function LookRay()
{
	var direction = transform.TransformDirection(Vector3.forward);
	var ray = Camera.main.ScreenPointToRay(Vector3(Screen.width/2, Screen.height/2,0));
	var hit : RaycastHit;
	
	
	
	if(Physics.Raycast(ray, hit, range) == false)
	{
		if(objectPreviouslyHit != null)
		{
			objectPreviouslyHit.transform.SendMessage("DisableGUI", SendMessageOptions.DontRequireReceiver);
			objectPreviouslyHit = null;
		}
		
		return;
	}
	
	if((objectPreviouslyHit != hit)  (objectPreviouslyHit != null))
	{
		objectPreviouslyHit.transform.SendMessage("DisableGUI", SendMessageOptions.DontRequireReceiver);
		objectPreviouslyHit = null;
	}
	
	Debug.DrawLine(ray.origin, hit.point, Color.red);
	
	if(hit.rigidbody == null)
		return;
		
	hit.transform.SendMessage("EnableGUI", SendMessageOptions.DontRequireReceiver);
	
	objectPreviouslyHit = hit.rigidbody;
	
}

EnemyHealth Enable/Disable Functions

function OnGUI()
{
	if(flag)
	{
		GUI.Box(Rect(200, 200, 100, 50), "Enemy HP: " + hp.ToString());
	}
	if(!flag)
	{
		GUI.enabled = false;
	}
	
}

function EnableGUI()
{
	flag = true;
}

function DisableGUI()
{
	flag = false;
}
5

Glad it worked for you and thank you for posting back the modified script for others to make use of.

6

An alternative that worked for me (might help out) is as follows. Slightly different example but hopefully makes sense:

if (Physics.Raycast(ray, out raycastHit, 10.0f))
        {
            // Select Menu Item look at
            if (raycastHit.collider.tag == "MenuItem") { //in the editor, tag anything you want to interact with and use it here
                raycastHit.collider.gameObject.GetComponent<MenuItemManager> ().SetToSelectedState (true);
                lastHitMenuItem = raycastHit.collider.gameObject;
            } else {
               // Deselect the menu item no longer looked at
                lastHitMenuItem.gameObject.GetComponent<MenuItemManager> ().SetToSelectedState (false);
            }

        }