CircleCast经过对撞机

Question

I'm working on a custom physics behaviour and use CircleCast to determine whether there is ground/wall or not. But in some cases CircleCast goes through a collider without hitting it. It seems that the issue appears when start circle a little bit overlaps a collider.

How do I fix it, or what do I do wrong?

using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour
{
    public Rigidbody2D ball;
    public CircleCollider2D circleCollider;
    public float speed;
    public LayerMask layerMask;
    public bool grounded;
    public Transform graphics;
    public Transform startCast, endCast;
    public GameObject tempBall;

    private int maxPathSize = 5;
    private Queue<GameObject> path;
    private float realRadius;
    private Vector2 roughDirection;
    private float rayLength;
    private Vector2 realDirection;
    private Vector2 gravity;
    private Vector2 preferedDirectionOfMove;

    // Use this for initialization
    void Start()
    {
        path = new Queue<GameObject>();
        realRadius = circleCollider.radius * ball.transform.localScale.x;
        rayLength = realRadius + (realRadius / 10);
        gravity = new Vector2(0, -9.81f);
    }

    // Update is called once per frame
    void Update()
    {
        // if (Time.frameCount % 10 == 0)
        {
            preferedDirectionOfMove = gravity;
            if (Input.GetKey(KeyCode.RightArrow) && grounded)
            {
                preferedDirectionOfMove = ball.transform.right;
            }
            if (Input.GetKey(KeyCode.LeftArrow) && grounded)
            {
                preferedDirectionOfMove = -ball.transform.right;
            }

            Move();

        }
    }

    void Move()
    {
        if (grounded && preferedDirectionOfMove == gravity)
            return;
        Debug.Log("***********");
        AddToPath(ball.position);
        realDirection = (preferedDirectionOfMove * speed * Time.deltaTime);
        Color color = Color.black;
        Vector2 oldPos = ball.position;
        Color colorX = RandomColor();
        DrawX(ball.position, colorX, 0.2f, 1, 0.5f);
        RaycastHit2D hit = Physics2D.CircleCast(ball.position, realRadius, realDirection.normalized, realDirection.magnitude, layerMask);
        if (hit)
        {
            DrawX(hit.point, colorX, 0.2f, 0.5f, 1.5f);
            SetAngle(hit);
            ball.position = GetNewPosition(hit);
            grounded = true;
            Debug.Log("grounded: " + true);
        }
        else
        {
            ball.position += realDirection;
            DrawX(ball.position, colorX, 0.2f, 0.5f, 1.5f);
            Debug.Log("grounded: " + false);
            color = Color.red;
            grounded = false;
        }
        Debug.DrawLine(oldPos, ball.position, color, 1);
    }

    void AddToPath(Vector2 position)
    {
        GameObject go = Instantiate(tempBall, position, Quaternion.identity) as GameObject;
        if (path.Count >= 5)
        {
            Destroy(path.Dequeue());
        }
        path.Enqueue(go);
    }

    void DrawX(Vector2 position, Color color, float size, float duration, float shape)
    {
        Debug.DrawLine(position - Vector2.one * (size / 2f), position + Vector2.one * (size / 2f), color, duration);
        Debug.DrawLine(position + new Vector2(-1 * shape, 1) * (size / 2f), position + new Vector2(1, -1 * shape) * (size / 2f), color, duration);
    }

    Color RandomColor()
    {
        return new Color(Random.Range(0f, 1f), Random.Range(0f, 1f), Random.Range(0f, 1f), 1);
    }

    Vector2 GetNewPosition(RaycastHit2D hit)
    {
        return hit.point + ((Vector2)hit.normal * realRadius);
    }

    void SetAngle(RaycastHit2D hit)
    {
        float angle2 = AngleAtan2(hit.normal, Vector2.right);
        ball.MoveRotation(angle2);
    }

    float AngleAtan2(Vector2 from, Vector2 to)
    {
        return Mathf.Rad2Deg * (Mathf.Atan2(to.y, to.x) - Mathf.Atan2(from.x, from.y));
    }

    void OnCollisionEnter2D(Collision2D collision)
    {
        Debug.Log("collision enter");
    }
}

Answer 1

Not registering hits when the casted object overlaps a collider at the start position is the default behavior. To fix this, check the Queries Start In Colliders box in the Physics 2D Manager in Project Settings .

If you don't want this behavior for all queries, you may want to look at ray casting instead since raycasts have a much lower chance of starting in a collider. If you do decide to go with a ray cast, untick the above box and start the ray cast inside your player/ball's collider itself. That way you can be sure that you'll never miss any hits because of the ray starting inside the offending collider.