How to stop raycast when hitting an object in Unity?

Hi,

in my Unity game (top-down 2D shooter) there are some enemies flying along a path (via DOTween). My player casts a ray into the scene in order to get an enemy-object right in front of the player. So far so good.

Now the problem is that I want only one enemy-object as a result, i.e. the raycast should stop when it hits an enemy-object for the very first time. How do I achieve this?

I need only one enemy-object hit by the raycast because there is a crosshair in my game and when the raycast starts and the enemies fly along the path the crosshair jumps forth and back (and I don't want this - the crosshair should stay at the first enemy hit by the raycast). Any help, please?

raycast-video

This is my code (attached to the player):

Code (CSharp):

1. void FixedUpdate() {
2.      
3.         //crosshair: Cast a ray straight up.
4.         float _size = 12f;
5.             Vector2 _direction = this.transform.up;
6.             RaycastHit2D _hit = Physics2D.Raycast(this.transform.position, _direction, _size);
7.  
8.         if (_hit.collider != null && _hit.collider.tag == "EnemyShipTag") {
9.  
10.           // We touched something!
11.  
12.           Vector2 target = new Vector2(_hit.collider.gameObject.transform.position.x, _hit.collider.gameObject.transform.position.y);
13.  
14.             const float moveTime = 0.1f;
15.             float step;
16.  
17.           step = Vector2.Distance(crosshairGO.transform.position, target);
18.             crosshairGO.transform.position = Vector2.MoveTowards(crosshairGO.transform.position, target, step / moveTime * Time.deltaTime);
19.  
20.             Vector2 _pos3 = new Vector2(this.transform.position.x, crosshairGO.transform.position.y);
21.             crosshairGO.transform.position = _pos3;
22.             crosshairBegin = false;
23.        } else {
24.           // Nothing hit
25.  
26.           Vector2 _pos2 = new Vector2(this.transform.position.x, 4.5f);
27.             if (crosshairBegin) {
28.                 crosshairGO.transform.position = _pos2;
29.             } else {
30.                 Vector2 _pos4 = new Vector2(this.transform.position.x, crosshairGO.transform.position.y);
31.                 crosshairGO.transform.position = _pos4;
32.             }
33.        }
34.  
35.  
36.     }

 

My initial thought is to add a bool like "targetFound" or something and then make an IF condition that determines whether or not the raycast should be used. Then, you could use a timer or some other function to change that "targetFound" bool back to false and then the raycast would activate again until it finds another enemy.

Code (CSharp):

1. if(targetFound == false)
2. {
3.     RaycastHit2D _hit = Physics2D.Raycast(this.transform.position, _direction, _size);
4. }

Maybe something like that?

 

That's an interesting idea. I will check this out! Thanks for the hint, dude!

Ok - I tested it and I get weird results with this kind of approach.

Some guy at stack overflow told me that there is a solution at https://answers.unity.com/questions/384355/stopping-a-raycast-after-hit.html
but I'm not able to implement it into my code. Any help, please?

 

I think you may be misunderstanding what is happening. To me it looks like problem is not that raycast hits multiple objects, but that there are moments when raycast doesn't hit front "row" of enemies so it goes through to back row, and so naturally your crosshair will move because enemy hit is in the back.

So it's not so much problem with code but design issue. I think it would be easier to notice if you did debug drawing of rays / hitboxes

 

@Xarnowit: Yes, there are gaps and then the ray hits the back row. I understand the problem now. Thanks for your help, dude!