有没有负索引图这样的东西？索引超出了数组的界限。

Question

我有一个像这样的图表来建立我的统一项目：

public class Point
{
    public int X { get; set; }
    public int Y { get; set; }

    public Point(int x, int y)
    {
        this.X = x;
        this.Y = y;
    }

    public override bool Equals(object obj)
    {
        if (obj == null)
        {
            return false;
        }
        if (obj is Point)
        {
            Point p = obj as Point;
            return this.X == p.X && this.Y == p.Y;
        }
        return false;
    }

    public override int GetHashCode()
    {
        unchecked
        {
            int hash = 6949;
            hash = hash * 7907 + X.GetHashCode();
            hash = hash * 7907 + Y.GetHashCode();
            return hash;
        }
    }

    public override string ToString()
    {
        return "P(" + this.X + ", " + this.Y + ")";
    }
}

public enum CellType
{
    Empty,
    Road,
    Structure,
    SpecialStructure,
    None
}

public class Grid
{
    public CellType[,] _grid;
    private int _width;
    public int Width { get { return _width; } }
    private int _height;
    public int Height { get { return _height; } }

    public List<Point> _roadList = new List<Point>();
    public List<Point> _specialStructure = new List<Point>();
    public List<Point> _houseStructure = new List<Point>();

    public Grid(int width, int height)
    {
        _width = width;
        _height = height;
        _grid = new CellType[width, height];
    }

  

    // Adding index operator to our Grid class so that we can use grid[][] to access specific cell from our grid. 
    public CellType this[int i, int j]
    {
        get
        {
            return _grid[i, j];
        }
        set
        {
            if (value == CellType.Road)
            {
                _roadList.Add(new Point(i, j));
            }
            if (value == CellType.SpecialStructure)
            {
                _specialStructure.Add(new Point(i, j));
            }
            if (value == CellType.Structure)
            {
                _houseStructure.Add(new Point(i, j));
            }
            _grid[i, j] = value;
        }
    }

我正在使用L系统算法实例化一系列游戏对象，并将它们的X和Z位置添加到图中，如下所示：

public Grid AddToGrid(Vector3Int position, string type)
    {
        //CellType parsed_enum = (CellType)System.Enum.Parse(typeof(CellType), type);
        switch (type)
        {
            case "Structure":
                placementGrid._houseStructure.Add(new Point((int)position.x, (int)position.z));
                break;
            case "SpecialStructure":
                placementGrid._specialStructure.Add(new Point((int)position.x, (int)position.z));
                break;
            case "Road":
                placementGrid._roadList.Add(new Point((int)position.x, (int)position.z));
                break;
        }

        return placementGrid;
    }

然后在我的一个脚本中，我调用了另一个函数：

 public List<Point> GetWakableAdjacentCells(int x, int y, bool isAgent)
    {
        List<Point> adjacentCells = GetAllAdjacentCells(x, y);
        
        Debug.Log("Adjacent Cells"+ adjacentCells.Count);//3
        Debug.Log("X"+x); //-1
        Debug.Log("Y"+y);//1
        for (int i = adjacentCells.Count - 1; i >= 0; i--)
        {
            Debug.Log(adjacentCells[i].X); //-1
            Debug.Log(adjacentCells[i].Y);//2
            if (IsCellWakable(_grid[adjacentCells[i].X, adjacentCells[i].Y], isAgent) == false)
            {
                adjacentCells.RemoveAt(i);
            }
        }
        return adjacentCells;
    }

但这表示在if条件下，"index超出了数组的界限“。为了方便起见，我对变量旁边的每个相关值进行了注释。

The function this condition is checking is this:

     public static bool IsCellWakable(CellType cellType, bool aiAgent = false)
        {
            Debug.Log("boo");
            if (aiAgent)
            {
                return cellType == CellType.Road;
            }
            return cellType == CellType.Empty || cellType == CellType.Road;
        }

我做错了什么？

是否有一种实现网格的方式可以访问减值？

Answer 1

好吧，你说自己

// -1

-> -1不能成为c#中的有效索引。

如果你想绕一圈，你很可能可以。

public CellType this[int i, int j]
{
    get
    {
        i = (i % _width) + _width) % _width;
        j = (j % _height) + _height) % _height;
        return _grid[i, j];
    }
    set
    {
        i = (i % _width) + _width) % _width;
        j = (j % _height) + _height) % _height;

        switch(value)
        {
            case CellType.Road:
                _roadList.Add(new Point(i, j));
                break;

            case CellType.SpecialStructure:
                _specialStructure.Add(new Point(i, j));
                break;
        
            case CellType.Structure:
                _houseStructure.Add(new Point(i, j));
                break;
        }
        _grid[i, j] = value;
    }
}

当然，这意味着你的网格基本上是“无限”的，跨越顶板，你将再次处于底部等等。