Bug with Circle Cast

Hi everybody.
I think there's a problem with the Physcis2D.CircleCast() method.

I do a CircleCast from my Character to know if there's something forward it. But, if I hit a wall and go in the other direction, sometimes, the CircleCast hit my Character ! I disabled the option "Queries Start In Colliders" in Physics 2D, tried to use it in all kind of Updates, tried to use an offset for the origin of the CircleCast... nothing changes.

You'll have to try more than once to make the bug happen, it's occasional.

That's my script. I made a project just to show you what happens if you don't want to make it :
https://drive.google.com/open?id=0BylYgxxY1FtpUWI1X05Rc282dm8

Code (CSharp):

1. using UnityEngine;
2.  
3. public class Character : MonoBehaviour
4. {
5.  
6.     private Rigidbody2D m_Rigidbody = null;
7.  
8.     [Header("Settings")]
9.  
10.     [SerializeField]
11.     private float m_Acceleration = 1500.0f;
12.  
13.     [SerializeField]
14.     private float m_ObstacleDetectionRange = 1.0f;
15.  
16.     [SerializeField]
17.     private float m_ObstacleDetectionRadius = 0.3f;
18.  
19.     private void Awake()
20.     {
21.         m_Rigidbody = GetComponent<Rigidbody2D>();
22.     }
23.  
24.     /*
25.      * Nothing different if used in Update().
26.      */
27.  
28.     private void FixedUpdate()
29.     {
30.         CheckMovement(Time.fixedDeltaTime);
31.     }
32.  
33.     /// <summary>
34.     /// Check the movement input
35.     /// </summary>
36.     private void CheckMovement(float _DeltaTime)
37.     {
38.         float horizontalMovement = Input.GetAxisRaw("Horizontal");
39.  
40.         Move(Vector3.right * horizontalMovement, _DeltaTime);
41.     }
42.  
43.     /// <summary>
44.     /// Make this Character move if it can.
45.     /// </summary>
46.     private void Move(Vector3 _Direction, float _DeltaTime)
47.     {
48.         if (_Direction != Vector3.zero && CanMove(_Direction))
49.         {
50.             if (m_Rigidbody != null)
51.             {
52.                 m_Rigidbody.AddForce(_Direction * m_Acceleration * _DeltaTime);
53.             }
54.  
55.             else
56.             {
57.                 Debug.LogWarning("No Rigidbody 2D on Character.");
58.             }
59.         }
60.     }
61.  
62.     /// <summary>
63.     /// Check if there's no obstacles in the given direction.
64.     /// </summary>
65.     private bool CanMove(Vector3 _Direction)
66.     {
67.         _Direction.Normalize();
68.  
69.         RaycastHit2D hitResult = Physics2D.CircleCast(transform.position, m_ObstacleDetectionRadius, _Direction, m_ObstacleDetectionRange);
70.  
71.         Debug.Log("Hit = " + hitResult.collider);
72.  
73.         return (hitResult.collider == null);
74.     }
75.  
76. }

Thanks for any help

 

hi,

I didn't read your code (well, I did read one line related to this question) but have you tried just using circleCast with specified layerMask ?

That way you can completely avoid hitting your raycast source.

 

Yeah, I tried to do it. A good solution is to ignore the collider of my character in its Awake, but there I don't want to work around the problem, but to solve it.

I can't use a layer mask, because in my game my character has to avoid collision with itself, but not with other characters.

 

@DaCookie - maybe just make your layerMask configured in different manner, so that player collides with characters too?

 

But I want all my characters can detect all characters but themselves... I don't think there's a way to do that with Layers and Physics settings :/

 

@DaCookie - sure you can:

If you are controlling the only character that needs to raycast others:
1. Place your player(s) in Layer "Player". Place your other characters in Layer "OtherCharacters".
2. In Physics settings, un-tick Player-Player collision. But keep Player-OtherCharacters on.
3. In your sphere cast, use "OtherCharacters" as layerMask.

Then again, if this test is going to happen from perspective of any character, then maybe just change the layer of that character temporarily, runtime when that character does raycast?

 

This solution is good but... Absolutely twisted !

I just want to avoid the collision with myself at CircleCast, and that behaviour HAVE TO be the normal behaviour... So should I use a solution like this or be sure this is a bug (and will be resolved )?

 

@DaCookie

Well, I just mentioned these without thinking much more further - maybe they might help you... or not.

Then there is Physics2D.CircleCastAll -> you could just use it and ignore raycaster itself in each case based on name/tag whatever.

Or use transformPoint to offset start of the raycast in front of your character.

Or use what you were already using, do you really have to capture each/every raycast, does it actually matter, if x is missed and one after it is used?

 

Did you try to open my example project that I post ? That's the new version (with gizmos and settings in editor) :

https://drive.google.com/open?id=0BylYgxxY1FtpeDZrS3ZUWWc5NjA

I still have the same problem in. It's quite simple to reproduce the "bug". In the Testing scene, you'll see a Sphere and two Walls. You can move the Sphere using arrows.

The sphere cast a CircleCast from it in Vector3.right direction (blue gizmo). The Sphere can't move in the direction where something is hit by the Circle cast (so if you're going in a wall that you're too close, the Sphere won't be able to move).

Go against a wall. Then, press arrow in the opposite direction and quickly press the other direction. Now, the CircleCast must hit Character, the Sphere.
I thought it's because I'm using FixedUpdate(), but it do the same with Update().

If the Gizmo is blue, you can move, else, it's red. The GUI will say what is hit.
Enjoy

 

Thanks a lot to take care of your users

If you don't use this post, where can I know the results of that investigation ?

 

... Too efficient for me

 

You're right, I'm doing it in my real project, but I missed it in my example, sorry.