Hex distance

[whartung]

Well, I just found out that my hex distance maths don't work .

CLOSE! but...

There are all sorts of solutions on the internet (which I surveyed when I wrote mine a zillion years ago), but none are drag and drop specifically with the way are hexes are numbered, etc. And I can't explain what mine is doing (right or wrong) anyway.

So, curious what others are using.

Here's what I have.

    public int hexDistance(int x1, int y1, int x2, int y2) {

        int ax = x1 - floor2(y1);
        int ay = x1 + ceil2(y1);
        int bx = x2 - floor2(y2);
        int by = x2 + ceil2(y2);
        int dx = bx - ax;
        int dy = by - ay;
        if (Math.signum(dx) == Math.signum(dy)) {
            return Math.max(Math.abs(dx), Math.abs(dy));
        }
        return Math.abs(dx) + Math.abs(dy);
    }

    private int floor2(int x) {
        return ((x >= 0) ? (x / 2) : (x - 1) / 2);
    }

    private int ceil2(int x) {
        return ((x >= 0) ? ((x + 1) / 2) : x / 2);
    }

It fails for 1903 to 1805. I get 2 instead of 3. (Subsector format which is column and row order, so its column 19 and row 3).

hexDistance(19, 3, 18, 5)

Math.signum returns 0 for zeros, -1 for negative numbers and +1 for positive numbers (BASIC SGN function).

So, just curious what others are using for this.

 

[coliver988]

old c# code where W1, W2 were the hex worlds 0101, 0202 sort of thing

 public int calcDistance(string W1, string W2)
        {
            int ST1 = Convert.ToInt32(W1.Substring(0, 2));
            int CR1 = Convert.ToInt32(W1.Substring(2, 2));
            int ST2 = Convert.ToInt32(W2.Substring(0, 2));
            int CR2 = Convert.ToInt32(W2.Substring(2, 2));
            int STDistance, CRMin, CRMax, CRMod;

            STDistance = Math.Abs(ST1 - ST2);

            int CROffset = (STDistance / 2);

            int mod1 = ST1 % 2;
            int mod2 = ST2 % 2;
            if (mod1 == 1 & mod2 == 0)
                CROffset++;

            CRMin = CR1 - CROffset;
            CRMax = CRMin + STDistance;

            CRMod = 0;
            if (CR2 < CRMin)
                CRMod = CRMin - CR2;
            if (CR2 > CRMax)
                CRMod = CR2 - CRMax;

            STDistance += CRMod;

            return STDistance;
        }

 

[whartung]

That worked, thanks so much.

 

[coliver988]

I think I actually got it from the traveler map site. If you look over his API's and stuff he had directions for all kinds of fun stuff in there.

And quite welcome!