Is it possible to find the contact point of a circle collider 2D with another collider inside of OnTriggerEnter2D?

Question

Hello. I'm at a roadblock in my code trying to find a way to make a moving circle collider reflect off the walls in a linear fashion, similar to pong. After much research and help, I've found a good way to reflect the collider, but not a perfect way to detect the collision point. This code functions well if the collision point is accurate, but often times it isn't. I believe this is due to an unpredicted result from my raycast. I was wondering if anyone had a suggestion that could remove these unexpected results?

Some notes: My speed gets set from an exterior script. The trajectory is an angle converted to a Vector2, it's definitely accurate as well.

 public class sword : MonoBehaviour {
 
     public Rigidbody2D rb;
     public CircleCollider2D coll;
 
     private float spin;
     public float speed;
     public Vector2 trajectory;
     public GameObject Player;
     Animator anim;
     RaycastHit2D hit;
 
 
 
 
     // Use this for initialization
     void Start () {
         speed = 0.0f;
     }
 
 
     private void OnTriggerEnter2D(Collider2D collision)
     {
 
 
         if (collision.tag == "player" && speed <= 1)
         {
             transform.position = new Vector2(-1000, -1000);
             Player.GetComponent<movement>().equipped = true;
         }
         if (collision.tag == "solid")
         {
             hit = Physics2D.Raycast(transform.position, trajectory);
             trajectory = Vector2.Reflect(trajectory, hit.normal);
         }
     }
 
 
     private void FixedUpdate()
     {
         //constantly calculating new velocity
         rb.velocity = speed * trajectory;
         speed = speed * 0.93f; //drag
     }
 }

Answer 1

Answer by Cornelis-de-Jager · Nov 20, 2018 at 03:03 AM

To get the point of collision simply use:

 var point = collision.point;

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unity_szuBm7Q_m1sWyw · Nov 20, 2018 at 03:10 AM 0

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Unfortunately that is not a value when using OnTriggerEnter2D.

unity_szuBm7Q_m1sWyw · Nov 20, 2018 at 03:38 AM 0

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I have done it now in a way that uses OnCollisionEnter2D, but for some reason the if statement for when the tag == "solid" never triggers, even though it did before.

 public class sword : MonoBehaviour {
 
     public Rigidbody2D rb;
     public CircleCollider2D coll;
 
     private float spin;
     public float speed;
     public Vector2 trajectory;
     public GameObject Player;
     Animator anim;
     RaycastHit2D hit;
 
 
 
 
     // Use this for initialization
     void Start () {
         speed = 0.0f;
         anim = Player.GetComponent<Animator>();
     }
 
 
 
     private void OnCollisionEnter2D(Collision2D collision)
     {
 
         if (collision.gameObject.tag == "player")
         {
             transform.position = new Vector2(-1000, -1000);
             anim.SetBool("Sword", true);
             Player.GetComponent<movement>().equipped = true;
         }
         if (collision.gameObject.tag == "solid")
         {
             ContactPoint2D otherObject = collision.contacts[0];
             Debug.Log(collision);
 
             Vector2 hit = otherObject.point;
             Vector2 normal = otherObject.normal;
             trajectory = Vector2.Reflect(trajectory, normal);
 
         }
     }
 
     private void FixedUpdate()
     {
         //constantly calculating new velocity
         rb.velocity = speed * trajectory;
         speed = speed * 0.93f; //drag
         if (speed < 0.0001f)
         {
             speed = 0.0f;
         }
         if (speed > 1)
         {
             Physics2D.IgnoreCollision(Player.GetComponent<CircleCollider2D>(), coll, true);
         }
         else
         {
             Physics2D.IgnoreCollision(Player.GetComponent<CircleCollider2D>(), coll, false);
         }
     }
 }

Is it possible to find the contact point of a circle collider 2D with another collider inside of OnTriggerEnter2D?

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