Resolved I need help with some math (RayCast2D)

Hello,

I need to find a point in space that is on the same line of a ray cast after it has collided with an object.

I'll try to explain better. In my game there are lasers, that act kinda like a wall so it has an edge collider inside.
To set the laser line i use a line renderer and a raycast, i create a ray and then i change the points of the collider and line rencerer based on where the laser collided with an object.

I have also some special doors and the laser can pierce trough them.

My problem was to find a way to ignore the collision between the laser and the door.
At first i tried with "IgnoreCollision()" but it does not work. So i found out another way.

If the laser hit the door, i cast a second ray from the laser hit point plus 0.5. It works! But i only do it for 4 directions.

If the laser face LEFT the value is -0.5
If the laser face RIGHT is 0.5

Same for UP and Down.
But the laser can rotate to any angle.

How can i create a custom function that returns a Vector2 that would be the origin of the second raycast based on the laser rotation?

I Made this is Paint, maybe it helps to better understand.



Thanks in advance

 

you could use Physics.RaycastAll to find all of the objects the ray intersects. then sort them by distance, and if the first object hit can be pierced by the lazer, then continue onward to the next returned collision.

 

Thanks both for the help.

It seems there is a RayCastAll for 2D https://docs.unity3d.com/ScriptReference/Physics2D.RaycastAll.html
So i should use one of these functions:

Code (CSharp):

1.  
2.  
3. Physics2D.Raycast(Vector2 origin, Vector2 direction, ContactFilter2D contactFilter, List<RaycastHit2D> results, float distance = Mathf.Infinity);
4.  
5. Physics2D.RaycastAll(transform.position,transform.up,RaycastHit2D[] results);
6.  
7.  

I tired to use the List function, but i can't manage to make it work, on visual studio i get an error.
In the manual page (https://docs.unity3d.com/ScriptReference/Physics2D.Raycast.html) there is no example how to use the RayCast with a List.
In visual studio i get the error "The use of generic type List<T> requires arguments of type 1".

This is the line i wrote.

Code (CSharp):

1. Physics2D.Raycast(transform.position,transform.up, List<RaycastHit2D> hitList);

Can you show me how to use this?

Thanks

 

I know that. I found out what the issue was.

I forgot to add the contact filter parameter so the function was expecting a value for "distance" and not a List.


Thanks

 

Yeah,
at first i created the list instance and passed the list name but since i forgot to put the contact filter parameter i got the error, so i started to try other things like that wrong line i posted because i was freaking out, it's better not to do things like this when you are tired.

Anyway I have another question that is related to the lasers.

I have also some laser receivers, that activate some objects if a laser hit them.

My problem is that OnCollisionEnter() is not triggered if a laser hits them. I think it's related on how i move the edge collider points.
As i said before my laser also act as a wall and it has an edge collider inside with a radius of 0.05.

So my code is the following, after the raycast hits an object i call this function

Code (CSharp):

1.     void SetCollider()
2.     {          
3.         Vector2[] edgecollpoints;
4.         edgecollpoints = _edgecollider.points;
5.         edgecollpoints[0] = new Vector2(0f,0f);
6.         Vector2 localtoworldpoints = transform.InverseTransformPoint(_laserhitpoint);  
7.         edgecollpoints[1] = new Vector2(localtoworldpoints.x,localtoworldpoints.y);
8.         _edgecollider.points = edgecollpoints;
9.     }

This basically moves the collier points instantly and therefore the OnCollisionEnter() is not working.
I also tried the OnCollisionStay and it's the same behavior, the collision event is not registered somehow.

It there a way i can solve this?

I already thought of some alternatives like coroutines and raycasts but i would like to use the collision events because it's better and simpler.

Thanks

 

My bad(i will try to be more precise next time) i used the correct callbakcs "OnCollisionEnter2D" and it does not work, same thing with OnCollisionStay2D() .

The collision is not registered.

How can i force it to register the collision?
I used OnCollisionStay because it should run on every call of FixedUpdate right?
It still does not work, it's like the colliders do not touch eachother.

You are suggesting to use a different type of check, like collider.isoverlapping, or collider.istouching during FixedUpdate?

I was told that those calls in FixedUpdate are expensive, because are called every 0.02 seconds.

I may be wrong but the OnCollisionEnter2D seems more performing since are only called once.

Any alternatives to OnCollisionEnter2D/OnCollisionExit2D ?

 

I need to change the points, to test it without moving the points i have to move the LaserReceiver instead and it's not supposed to move in the game.

I solved it with a workaround, i check if the laser hits a laserreceiver and then execute a public function to activate it from the laser script.

But since the collision problem is still there.

I can post my function but it's pretty long (104 lines) and i was told my code is weird because i use a lot of spaces, if you don't struggle to read it here is the RayCast function.

Spoiler: Code

Code (CSharp):

1. void RaycastStart()
2.     {
3.  
4.         if(OnLaserRayCastEvent!= null)
5.         {
6.             OnLaserRayCastEvent();
7.         }
8.         _linerenderer.enabled =true;
9.         _edgecollider.enabled =true;
10.  
11.         ContactFilter2D contactFilter = new ContactFilter2D().NoFilter();
12.  
13.      
14.  
15.         if(_boxSigns.Length ==0)
16.         {
17.             //hitresults = Physics2D.Raycast(transform.position,transform.up);
18.  
19.             hit = Physics2D.Raycast(transform.position,transform.up);
20.  
21.         }
22.         else
23.         {
24.             if(BoxesStatusActive())
25.             {
26.             // _lasercollidList.Clear();
27.             hit = Physics2D.Raycast(transform.position,transform.up);
28.             }
29.             else
30.             {
31.             hit = Physics2D.Raycast(transform.position,transform.up,0.5f);
32.             _linerenderer.enabled =false;
33.             _edgecollider.enabled =false;
34.             }
35.         }
36.      
37.      
38.         if(hit.collider.gameObject.tag == "Barrier")
39.         {
40.             //Debug.Log("BARRIER HIT");
41.             _lasercollidList.Clear();
42.             Physics2D.Raycast(transform.position,transform.up, contactFilter, hitList );
43.              
44.              
45.             for (int i = 0; i < hitList.Count; i++)
46.             {
47.                 _lasercollidList.Add( hitList[i].collider.gameObject);
48.          
49.  
50.  
51.  
52.                 if(hitList[i].collider.gameObject.GetComponent<Barrier>()!=null)
53.                 {
54.                     if(_lasercolor ==_lasercollidList[i].GetComponent<Barrier>().barrierColor)
55.                     {
56.                         Debug.Log("BARRIER SAME COLOR");
57.                         _laserhitpoint = hitList[i+1].point;
58.                         _linerenderer.SetPosition(0, transform.position);
59.                         _linerenderer.SetPosition(1, _laserhitpoint);
60.                     // Physics2D.IgnoreCollision(_edgecollider,_collidBarrier._edgecollider,false);
61.                      
62.                     }
63.                     else
64.                     {
65.                         Debug.Log("BARRIER COLOR NOO");
66.                         _laserhitpoint = hit.point;
67.                         _linerenderer.SetPosition(0, transform.position);
68.                         _linerenderer.SetPosition(1, _laserhitpoint);    
69.  
70.                     }
71.                 }
72.             }
73.              
74.         }
75. // This if statement is the one i added for the workaround, i can delete it and use the LaserReceiver collision instead
76.         else if(hit.collider.gameObject.tag == "LaserReceivers")
77.         {
78.             hit.collider.gameObject.GetComponent<Laserreciver>()._laserwall = this;
79.             hit.collider.gameObject.GetComponent<Laserreciver>().OnLaserCollision();
80.              _laserhitpoint = hit.point;
81.                 _linerenderer.SetPosition(0, transform.position);
82.                  
83.                 _linerenderer.SetPosition(1, _laserhitpoint);
84.  
85.         }
86.         else // Any other object is hit so laser stops
87.         {
88.             //Debug.Log("SetLaserPoint");
89.                 _laserhitpoint = hit.point;
90.                 _linerenderer.SetPosition(0, transform.position);
91.                  
92.                 _linerenderer.SetPosition(1, _laserhitpoint);
93.         }
94.      
95.  
96.        // Debug.Log("hitobj   "+hit.collider.gameObject);
97.  
98.          
99.         SetCollider();
100.  
101.         Debug.DrawRay(transform.position,transform.up, Color.red, Mathf.Infinity,false);      
102.     }

I change the points after the raycast hits an object.

I used unity events system to avoid shooting rays continuously on fixed Update.

So any time an object is activated, for example a door is opened or closed, an event is triggered and the RayCastStart function is executed, then it checks the object type it collide with, then checks if the object can be pierced, then it sets the LineRenderer points, then it moves the collider points.

It works with well with the doors (Barriers in the code) but with the Laserreceiver it does not.


I

 

Off topic, but it's so incredible to see actual UT devs helping so patiently in the forums like this. The generosity and patience is incredible, I don't know of any other software with engagement like this.

 

The code i showed you it's from the Laser script, where i change the collider points.

The OnCollisionEnter2D() that does not work is on the LaserReciver script.

Maybe I explained it wrong.

In the Laser script:
I use the Event system to cast a ray after an object has been activated.(So that i avoid to cast ray repeatedly)
Object.Changestateevent += RaycastStart;
The RaycastStart() function shoot a ray and sets the LineRenderer points on the laser.
At the end of RaycastStart i call "SetCollider()" that moves the points of the collider to match the LineRenderer points.


In the LaserReceiver script:
I have OnCollisionEnter2D() that does not register the collision with the laser collider.
I still don't know why it does not register the collision.


I solved it with a custom function in the LaserReceiver script (that basically
substitute OnCollision2DEnter )

public void OnLaserCollision();
That is executed from the Laser script after the ray hits a LaserReceiver object.

hit.collider.gameObject.GetComponent<Laserreciver>().OnLaserCollision();


The simulation should be always running, i don't get it.
It's like if i increase a collider's size at runtime it does not register collision callbacks if it's not in the FixedUpdate method?


Thanks

Yeah i am surprised too.

 

I'll DM you.

Btw thank you very much for your help and availability.