如何在 Unity 的子对象中访问车轮碰撞器

Question

在 Unity 中，我的玩家游戏对象有 4 个轮子，它们都包含轮子碰撞器。我想得到这些的转速。

我写了这段代码，但在第 33 行它抛出 index/argument 越界异常，这意味着它试图使用 'GetChild(i)' 访问的索引不可访问。第 33 行是

 wColliders[i] = gameObject.transform.GetChild(i).gameObject.GetComponent<WheelCollider>();

我的播放器有 5 个子对象，其中 4 个有轮子碰撞器。如何解决？

```
public class PlayerController : MonoBehaviour
 {

    //[SerializeField] private float speed = 10f;
    [SerializeField] private float speed;
    [SerializeField] private float rpm;
    private float totalRpm;
    [SerializeField] private float horsePower;
    [SerializeField] private float turnSpeed;
     public float horizontalInput;
     public float forwardInput;

    [SerializeField] private GameObject centerOfMass;
    [SerializeField] TextMeshProUGUI speedometerText;
    [SerializeField] TextMeshProUGUI rpmText;
    
    List<WheelCollider> wColliders;
    private Rigidbody playerRb;
    // Start is called before the first frame update
    void Start()
    {
        playerRb = GetComponent<Rigidbody>();

        playerRb.centerOfMass = centerOfMass.transform.position;

        wColliders = new List<WheelCollider>();
        for(int i = 0; i < 4; i++)
        {
            wColliders[i] = gameObject.transform.GetChild(i).gameObject.GetComponent<WheelCollider>();
        }
    }

    // Update is called once per frame
    void FixedUpdate()
    {
        horizontalInput = Input.GetAxis("Horizontal");
        forwardInput = Input.GetAxis("Vertical");

        playerRb.AddRelativeForce(Vector3.forward * horsePower * forwardInput);
       
        transform.Rotate(Vector3.up, Time.deltaTime * turnSpeed * horizontalInput);

        speed = playerRb.velocity.magnitude;
        speed = Mathf.RoundToInt(speed);
        speedometerText.SetText("Speed: " + speed);

        for(int i = 0; i < wColliders.Count; i++)
        {
            totalRpm += wColliders[i].rpm;
        }

        rpm = Mathf.Round(totalRpm / wColliders.Count);

        rpmText.SetText("RPM: " + rpm);
    }
}

Answer 1

你得到 IndexOutOfBoundsException 不是因为 Unity 没有找到 child 而是因为你试图 access/set

wColliders[i]

空列表。尚未添加任何项目，因此您无法通过索引访问它们。

您更愿意使用 List<T>.Add

for(var i = 0; i < 4; i++)
{
    wColliders.Add(transform.GetChild(i).GetComponent<WheelCollider>());
}

或者实际上更简单地使用 GetComponentsInChildren

wColliders = GetComponentsInChildren<WheelCollider>(true).ToList();

如何在 Unity 的子对象中访问车轮碰撞器

How to access wheel collider in a child object in Unity

c#

unity3d

child-objects

wheelcollider