生成三角/六角坐标 (xyz)

Question

我试图提出一个迭代函数来生成六角形网格的 xyz 坐标。使用起始六边形位置（为简单起见，假设为 0,0,0），我想计算每个连续的六边形“环”的坐标，如下所示：

到目前为止，我所能想到的就是这个（javascript 中的示例）：

var radius = 3
var xyz = [0,0,0];

// for each ring
for (var i = 0; i < radius; i++) {
    var tpRing = i*6;
    var tpVect = tpRing/3;
    // for each vector of ring
    for (var j = 0; j < 3; j++) {
        // for each tile in vector
        for(var k = 0; k < tpVect; k++) {
            xyz[0] = ???;
            xyz[1] = ???;
            xyz[2] = ???;
            console.log(xyz);
        }
    }
}

我知道每个环比前一个环多包含 6 个点，并且每个 120° 向量对于从中心。我还知道所有图块的 x + y + z = 0 。但是如何生成遵循以下顺序的坐标列表呢？

    0, 0, 0

    0,-1, 1
    1,-1, 0
    1, 0,-1
    0, 1,-1
   -1, 1, 0
   -1, 0, 1

    0,-2, 2
    1,-2, 1
    2,-2, 0
    2,-1,-1
    2, 0,-2
    1, 1,-2
    0, 2,-2
   -1, 2,-1
   -2, 2, 0
   -2, 1, 1
   -2, 0, 2
   -1,-1, 2

Answer 1

这是一个有趣的谜题。

O(radius²)，但（希望）比 Ofri 的风格更多一些 我突然想到，可以像使用方向（移动）向量绕环“行走”一样生成坐标，并且转动相当于围绕移动向量移动零。

此版本还比 Eric 的解决方案 具有优势，因为它从不触及无效坐标（Eric 的解决方案拒绝它们，但这个解决方案从不涉及无效坐标）甚至必须测试它们）。

# enumerate coords in rings 1..n-1; this doesn't work for the origin
for ring in range(1,4):
    # start in the upper right corner ...
    (x,y,z) = (0,-ring,ring)
    # ... moving clockwise (south-east, or +x,-z)
    move = [1,0,-1]         

    # each ring has six more coordinates than the last
    for i in range(6*ring):
        # print first to get the starting hex for this ring
        print "%d/%d: (%d,%d,%d) " % (ring,i,x,y,z)
        # then move to the next hex
        (x,y,z) = map(sum, zip((x,y,z), move))

        # when a coordinate has a zero in it, we're in a corner of
        # the ring, so we need to turn right
        if 0 in (x,y,z):
            # left shift the zero through the move vector for a
            # right turn
            i = move.index(0)
            (move[i-1],move[i]) = (move[i],move[i-1])

    print # blank line between rings

为 python 的序列切片欢呼三声。

Answer 2

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
ctx.textAlign = "center";

const radius = 20;
const altitude = Math.sqrt(3) * radius;
const total = 3;
for (let x = -total; x <= total; x++) {
    let y1 = Math.max(-total, -x-total);
    let y2 = Math.min(total, -x+total);
    for (let y = y1; y <= y2; y++) {
        let xx = x * altitude + Math.cos(1/3*Math.PI) * y * altitude;
        let yy = y * radius * 1.5;
        xx += canvas.width/2;
        yy += canvas.height/2;
        drawHex(xx, yy, radius);
        ctx.fillText(x+","+y, xx, yy);
    }
}

function drawHex(x, y, radius){
    ctx.beginPath();
    for(let a = 0; a < Math.PI*2; a+=Math.PI/3){
        let xx = Math.sin(a) * radius + x;
        let yy = Math.cos(a) * radius + y;
        if(a == 0) ctx.moveTo(xx, yy);
        else ctx.lineTo(xx, yy);
    }
    ctx.stroke();
}

<canvas id="canvas" width=250 height=250>

Answer 3

在尝试了这两个选项之后，我选择了 Ofri 的解决方案，因为它速度稍快一些，并且可以轻松提供初始偏移值。我的代码现在如下所示：

var xyz = [-2,2,0];
var radius = 16;
var deltas = [[1,0,-1],[0,1,-1],[-1,1,0],[-1,0,1],[0,-1,1],[1,-1,0]];
for(var i = 0; i < radius; i++) {
        var x = xyz[0];
        var y = xyz[1]-i;
        var z = xyz[2]+i;
        for(var j = 0; j < 6; j++) {
                for(var k = 0; k < i; k++) {
                        x = x+deltas[j][0]
                        y = y+deltas[j][1]
                        z = z+deltas[j][2]
                        placeTile([x,y,z]);
                }
        }
}

placeTile 方法使用 cloneNode 复制预定义的 SVG 元素，每个图块的执行时间大约为 0.5 毫秒，这已经足够好了。非常感谢 tehMick 和 Ofri 的帮助！

Answer 4

不仅是x + y + z = 0，而且x、y和z的绝对值都等于环半径的两倍。这应该足以识别每个连续环上的每个六边形：

var radius = 4;
for(var i = 0; i < radius; i++)
{
    for(var j = -i; j <= i; j++)
    for(var k = -i; k <= i; k++)
    for(var l = -i; l <= i; l++)
        if(Math.abs(j) + Math.abs(k) + Math.abs(l) == i*2 && j + k + l == 0)
            console.log(j + "," + k + "," + l);
    console.log("");
}

Answer 5

另一种可能的解决方案，运行时间为 O(radius²)，与 O(radius⁴) 不同a href="https://stackoverflow.com/a/2049274/241211">tehMick 的解决方案（以牺牲大量风格为代价）是这样的：

radius = 4
for r in range(radius):
    print "radius %d" % r
    x = 0
    y = -r
    z = +r
    print x,y,z
    for i in range(r):
        x = x+1
        z = z-1
        print x,y,z
    for i in range(r):
        y = y+1
        z = z-1
        print x,y,z
    for i in range(r):
        x = x-1
        y = y+1
        print x,y,z
    for i in range(r):
        x = x-1
        z = z+1
        print x,y,z
    for i in range(r):
        y = y-1
        z = z+1
        print x,y,z
    for i in range(r-1):
        x = x+1
        y = y-1
        print x,y,z

或者写得更简洁一点：

radius = 4
deltas = [[1,0,-1],[0,1,-1],[-1,1,0],[-1,0,1],[0,-1,1],[1,-1,0]]
for r in range(radius):
    print "radius %d" % r
    x = 0
    y = -r
    z = +r
    print x,y,z
    for j in range(6):
        if j==5:
            num_of_hexas_in_edge = r-1
        else:
            num_of_hexas_in_edge = r
        for i in range(num_of_hexas_in_edge):
            x = x+deltas[j][0]
            y = y+deltas[j][1]
            z = z+deltas[j][2]            
            print x,y,z

它的灵感来自于事实六边形实际上位于六边形本身的外部，因此您可以找到其中 1 个点的坐标，然后通过移动其 6 条边来计算其他点的坐标。