如何将整数分配给列表中的对象

本文关键字：列表 对象 分配 整数 | 更新日期: 2023-09-27 18:29:37

所以我在一个列表中有对象，我试图为每个对象分配一个角度。目前我有两个列表：

List<double> BulletAngles = new List<double>();
List<OvalShape> Bullets = new List<OvalShape>();

我对列表工作方式的看法显然很不一致。现在子弹是基于以下代码传播的：

foreach (OvalShape b in Bullets)
{
      int i = Bullets.IndexOf(b);
      if (b.Location.X > -10 && b.Location.X < (this.Width - 6) + 10
      && b.Location.Y > -10 && b.Location.Y < (this.Height - 30) + 10)
      {
          b.Left += Convert.ToInt32(bulletSpeed * Math.Cos(BulletAngles[i]));
          b.Top += Convert.ToInt32(bulletSpeed * Math.Sin(BulletAngles[i]));
      }
}

角度完全基于鼠标单击时的位置，但在测试时，所有项目符号都指向第一次鼠标单击的方向。这也是用于设置角度和放置在项目符号中的代码：

Point target = new Point(mousePos.X - origin.X, mousePos.Y - origin.Y);
OvalShape g = Bullet;
double y = Math.Atan2(target.Y, target.X);
g.Left = origin.X - (g.Width / 2);
g.Top = origin.Y - (g.Height / 2);
g.Visible = true;
BulletAngles.Add(y);
Bullets.Add(g);

如何将整数分配给列表中的对象

使用IndexOf方法可能不会返回您要查找的结果，因为此方法使用默认的相等比较器来确定相等。

虽然在两个单独的列表中包含与对象相关的属性是有问题的，并且可以通过将属性封装到一个对象中来更好地解决，如前所述。如果在遍历列表时尝试获取对象的索引，那么最好使用for语句而不是foreach语句。

for (int index = 0; index < Bullets.Count; index++)
{
    var b = Bullets[index];
    if (b.Location.X > -10 && b.Location.X < (this.Width - 6) + 10
        && b.Location.Y > -10 && b.Location.Y < (this.Height - 30) + 10)
    {
        b.Left += Convert.ToInt32(bulletSpeed*Math.Cos(BulletAngles[index]));
        b.Top += Convert.ToInt32(bulletSpeed * Math.Sin(BulletAngles[index]));
    }
}

下面是一个使用封装的示例：

public class OvalShapeBullet
{
    private readonly OvalShape _ovalShape;
    private Point _location;
    private readonly double _angle;
    private double _distance;
    public OvalShapeBullet(Point orgin, Point target, OvalShape ovalShape)
    {
        _ovalShape = ovalShape;
        _location = new Point(orgin.X - ((int)ovalShape.Width / 2), orgin.Y - ((int)ovalShape.Height / 2));
        _distance = Math.Sqrt((orgin.X - target.X) ^ 2 + (orgin.Y - target.Y) ^ 2);
        _angle = Math.Atan2(target.Y, target.X);
    }
    public Point Location { get { return _location; } }
    public bool Visible
    {
        get { return _ovalShape.Visible; }
        set { _ovalShape.Visible = value; }
    }
    /// <summary>
    /// Attempts to move bullet to target
    /// </summary>
    /// <param name="distance">The distance the bullt will travel</param>
    /// <returns>True if bullet connects with target</returns>
    public bool TryMoveToTarget(float distance)
    {
        if (_distance <= 0)
            return true;        // check if bullet has travelled far enough
        _location.X += (int)(distance * Math.Cos(_angle));
        _location.Y += (int)(distance * Math.Sin(_angle));
        _distance -= distance;
        return _distance <= 0;  // check if bullet has traveled far enough
    }
}

当原始语句变成单个列表声明时，您的代码就会变得更干净

List<OvalShapeBullet> Bullets = new List<OvalShapeBullet>();

创建新对象的处理

        Point target = new Point(mousePos.X - origin.X, mousePos.Y - origin.Y);
        OvalShapeBullet g = new OvalShapeBullet(mousePos, target, Bullet);
        g.Visible = true;
        Bullets.Add(g);

管理子弹的移动并检查目标连接

        foreach (OvalShapeBullet b in Bullets)
        {
            if (b.TryMoveToTarget(bulletSpeed))
            {
                // handle bullet has hit the target
                Bullets.Remove(b);
            }
        }
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