Question

想象一下三维空间的六边形空间。

每个图块的坐标为XYZ。我需要在同一平面上选择给定的单元邻居。使用SQL看起来像：

$tbDir = $y % 2 == 0 ? -1 : 1;

$result =  db_query('SELECT x,y,z FROM {cells} WHERE
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d OR
                    x = %d AND y = %d AND z = %d ',
                    $x, $y, $z,
                    $x-1, $y, $z,
                    $x+1, $y, $z,
                    $x, $y-1, $z,
                    $x, $y+1, $z,
                    $x+$tbDir, $y-1, $z,
                    $x+$tbDir, $y+1, $z);

但是，我不喜欢这样。也许有人知道更优化的算法？谢谢！

Answer 1

这看起来像你可以使用

x BETWEEN $x-1 AND $x+1 AND y BETWEEN $y-1 AND $y+1 AND z = $z

这可能不适用于$ tbDir部分。我将更详细地介绍一下这个案例。

好的，请尝试这个

WHERE   x BETWEEN ($x-1 AND $x+1 AND y = $y AND z = $z)
OR      (y BETWEEN $y-1 AND $y+1 AND x = $x AND z = $z)
OR      (y BETWEEN $y-1 AND $y+1 AND x = $x + $tbDir AND z = $z)

甚至

WHERE   (   (x BETWEEN $x-1 AND $x+1 AND y = $y )
            OR      (y BETWEEN $y-1 AND $y+1 AND x = $x)
            OR      (y BETWEEN $y-1 AND $y+1 AND x = $x + $tbDir)
        )
AND     z = $z

Answer 2

如果您的算法可以使用非正交坐标系，则可以轻松进行映射。在您的情况下，六角形瓦片的与轴平行的部分似乎是垂直的：

 / \ / \ / \
| a | b | c |
 \ / \ / \ / \
  | d | e | f |
 / \ / \ / \ /
| x | g | h | i

如果您可以接受偏斜的Y轴，那么您可以给a，d，g X坐标0（即Y轴穿过这些图块的中心）。（beh将X == 1，cfi X == 2，依此类推）。 x具有坐标（-1,2）。现在你可以像这样移动：

e -> f: x+1,y
e -> d: x-1,y
e -> b: x,  y-1
e -> c: x+1,y-1
e -> g: x-1,y+1
e -> h: x,  y+1

如您所见，这些动作现在完全独立于y位置。

在六边形场中选择邻居细胞

2 个答案: