[Freeciv-Dev] Re: (PR#6721) A Quincuncial topology

["Gregory Berkolaiko" <Gregory.Berkolaiko@xxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=6721 >

On Mon, 10 Nov 2003, Jason Short wrote:

> 
> <URL: http://rt.freeciv.org/Ticket/Display.html?id=6721 >
> 
> Jason Short wrote:
> > <URL: http://rt.freeciv.org/Ticket/Display.html?id=6721 >
> > 
> > Summary:
> > 
> > This topology is a crazy, kinda cool approximation of a sphere.  To get
> > it to work we'd have to have something that I will call
> > "mirror-wrapping".  For instance an 8x3 map that mirror-wrapped in the Y
> > (north-south) direction would look like
> > 
> >   xwvutsrq
> >   ponmlkji
> >   hgfedcba
> >   ponmlkji
> >   hgfedcba
> > 
> > where the capital letters are the normal positions (0,0) through (7,3).
> >  Thus for each Y wrap there is a mirroring of the X value
> > 
> >   Y = Y + map.ysize
> >   X = map.xsize - 1 - X
> 
> Err, this isn't quite right.  The map is mirrored over the pole with a 
> 180-degreen (pi) rotation.  So the actual math is a bit more 
> complicated, something like
> 
>    Y = -Y
>    X = map.xsize - 1 - X

I don't understand what these formulas are supposed to mean but presumably 
you want

   ABCDEFGH
   IJKLMNOP
   QRSTUVWX
   uvwxqrst

instead of what you wrote.

G.