在不使用 Unity3d 物理引擎的情况下旋转箭头

Question

我有这段代码可以在不使用统一物理引擎的情况下模拟弹丸的运动

IEnumerator LaunchProjectile(int angle, float speed)
{

    // Move projectile to the position of throwing object + add some offset if needed.
    Projectile.position = transform.position + new Vector3(0, 0f, 0);
    Projectile.rotation = transform.root.rotation;
    Debug.Log(transform.root.eulerAngles);

    // Calculate distance to target
    float target_Distance = speed * (Mathf.Sin(2 * firingAngle * Mathf.Deg2Rad) / gravity);

    // Extract the X  Y componenent of the velocity
    float Vx = Mathf.Sqrt(speed) * Mathf.Cos(firingAngle * Mathf.Deg2Rad);
    float Vy = Mathf.Sqrt(speed) * Mathf.Sin(firingAngle * Mathf.Deg2Rad); 

    // Calculate flight time.
    float flightDuration = target_Distance / Vx;

    this.arrowSimulationScript = Projectile.gameObject.GetComponentInChildren<ArrowSimulation>();

    float elapse_time = 0;

    while (!arrowSimulationScript.Collided())
    {
        Projectile.Translate(0, (Vy - (gravity * elapse_time)) * Time.deltaTime, Vx * Time.deltaTime);

        Projectile.LookAt(Projectile.position - new Vector3(0,  (Vy - (gravity * elapse_time)) * Time.deltaTime, Vx * Time.deltaTime));

        arrowSimulationScript.Velocity = new Vector3(0, (Vy - (gravity * elapse_time)) * Time.deltaTime, Vx * Time.deltaTime).magnitude;

        elapse_time += Time.deltaTime;

        yield return null;
    }
}

箭头朝附有此脚本的对象的方向发射。为了使箭头旋转，我使用这行代码：

Projectile.LookAt(Projectile.position - new Vector3(0,  (Vy - (gravity * elapse_time)) * Time.deltaTime, Vx * Time.deltaTime));

箭头向右移动，但尖端朝向 z 轴方向，而不是弓的方向。 这是该问题的视频： https://www.youtube.com/watch?v=cyK6DXxTw_E

如果我注释掉那行代码，箭的尖端朝向弓的方向飞行，但它不旋转。

Answer 1

试试这个

while (!arrowSimulationScript.Collided())
{
    Vector3 delta = new Vector3(0, (Vy - (gravity * elapse_time)) * Time.deltaTime, Vx * Time.deltaTime);
    Vector3 newPos = Projectile.position + delta;
    Vector3 offset = (newPos - Projectile.position);
    Vector3 magnitude = offset.magnitude;
    Vector3 newDir = offset.normalized;

    Projectile.rotation = Quaternion.LookRotation(newDir, Vector3.Cross(newDir, Projectile.right)));

    arrowSimulationScript.Velocity = magnitude;

    elapse_time += Time.deltaTime;
    Projectile.position = newPos;

    yield return null;
}