Creating a 2D Laser Beam

Most of the results I get for creating laser beams describe how to make Star Wars-like projectiles. That's not what I'm going for. Instead, I need a constant beam that stops when it hits (most) collider surfaces. This Live Training video is a great example of what I'm going for, except that my lasers are coming from traps in the environment, so they aren't anchored to the player; most of them are firing constantly instead of on input, and of course, mine are in a 2D environment:

Here is the code used in his example:

Code (CSharp):

1. IEnumerator FireLaser()
2. {
3.      line.enabled = true;
4.      while (Input.GetButton("Fire1"))
5.      {
6.           Ray ray = new Ray(transform.position, transform.forward);
7.           RaycastHit hit;
8.  
9.           line.SetPosition(0, ray.origin);
10.  
11.           if (Physics.Raycast(ray, out hit, 100))
12.                line.SetPosition(1, hit.point);
13.           else
14.                 line.SetPosition(1, ray.GetPoint(100));
15.  
16.           yield return null;
17.      }
18.  
19.      line.enabled = false;
20.  
21.      }
22. }
23.  

The documentation describes the LineRenderer as "The line renderer is used to draw free-floating lines in 3D space.", however since a Vector2 can be cast to a Vector3, that doesn't seem to be an issue.

Here is my code:

Code (CSharp):

1.     IEnumerator FireLaser()
2.     {
3.         line.enabled = true;
4.  
5.         while (laserOn)
6.         {
7.             Ray2D ray = new Ray2D(transform.position, transform.right);
8.             RaycastHit2D hit;
9.  
10.             line.SetPosition(0, ray.origin);
11.  
12.             if (Physics2D.Raycast(ray, out hit, distance))
13.                 line.SetPosition(1, hit.point);
14.             else
15.                 line.SetPosition(1, ray.GetPoint(distance));
16.  
17.             yield return null;
18.         }
19.         line.enabled = false;
20.     }

I'm getting two errors, both at the line that does the line that does the raycast:

The best overloaded method match for `UnityEngine.Physics2D.Raycast(UnityEngine.Vector2, UnityEngine.Vector2, float)' has some invalid arguments

Argument `#1' cannot convert `UnityEngine.Ray2D' expression to type `UnityEngine.Vector2'

So the normal (3D) Raycast has no trouble converting a 3D Ray to a Vector3, but the 2D Raycast can't seem to do the same for a Ray2D.

Did I make a mistake or is there a different way of going about this?

 

In the few months that we have had 2D features I have never had to learn or come across Ray2D and I would think that sooner or later there will be a tutorial by Unity on how to do this, but I am not going to have no idea on how to sort your code out, but I can over some troubleshooting tips from what it might be.

-A vector 2 requires and x and a y vaule make sure that they are in the correct place by checking the reference.

-Lastly RaycastHit2D is a function I think you should be using to cast http://docs.unity3d.com/ScriptReference/Physics2D.Raycast.html

But Like I said I have never come across it and will need to get learning soon, so can you keep me updated on the things you learn in case I need it some day!

 

Okay, I got it working. I've used 2D Raycasts before, so I just did it the way that I normally would, and it came together.

Code (CSharp):

1.     IEnumerator FireLaser()
2.     {
3.         line.enabled = true;
4.  
5.         while (laserOn)
6.         {
7.             Ray2D ray = new Ray2D(transform.position, transform.right);
8.             RaycastHit2D hit;
9.  
10.             line.SetPosition(0, ray.origin);
11.  
12.             hit = Physics2D.Raycast(ray.origin, Vector2.right, distance);
13.  
14.             if (hit.collider)
15.             {
16.                 line.SetPosition(1, hit.point);
17.             }
18.             else
19.                 line.SetPosition(1, ray.GetPoint(distance));
20.  
21.             yield return null;
22.         }
23.         line.enabled = false;
24.     }

The first two arguments in the Raycast code (in the example) still don't make any sense to me though. :/

 

If it works it works, half the time the code I right makes some sense, but other times I have no idea what something's are, for example matrix but when it works it works

 

You mean the Raycast origin and direction?

 

Ah, yes. I didn't realize that there are multiple ways to do a raycast, each with different arguments. I thought that (in the example), a Ray was being used as an argument where a vector should be.