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

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

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

Gregory Berkolaiko wrote:

> I don't understand what these formulas are supposed to mean but presumably 
> you want
> 
>    ABCDEFGH
>    IJKLMNOP
>    QRSTUVWX
>    uvwxqrst
> 
> instead of what you wrote.

No.  It is flipped/mirrored in the X direction, not shifted.  The above 
map is not legal because (for instance) Q and q do not have the same 
adjacent tiles.

The formulas represent the simplest form of wrapping.  So with

   Y = -Y - 1
   X = map.xsize - 1 - x

we are mirroring Y around the origin and mirroring X around the 
map.xsize/2 axis.

jason