[Freeciv-Dev] Re: e: suggestion/idea - the world is round

[Jules Bean <jules@xxxxxxxxxxxxxxx>]

On Fri, Jul 21, 2000 at 01:45:38PM +0200, Marc Strous wrote:
> 
> >Suppose the top projection is like this:
> >
> >
> >+--+------+--+
> >|F |  D   | G|
> >|  |      |  |
> >+--+------+--+
> >|  |      |  |
> >|  |      |  |
> >|B |  A   | C|
> >|  |      |  |
> >|  |      |  |
> >+--+------+--+
> >|  |      |  |
> >|H |  E   | I|
> >+--+------+--+
> >
> >Then area 'A' is /only/ part of the top project -- fine.
> >Area 'B' overlaps with the left projection, fine.
> >Area 'D' overlaps with the "behind" projection, fine.
> >
> >But what about area F?
> >
> F is the area where A, B and D all overlap. While you're looking at A, and 
> scroll into the direction of F, the map switches to projection B or D. 
> (without the need for instant redrawing due to the overlap).

However, suppose your view is centered absolutely over the point where
F,D,B,A touch.

Magnified view:

F   |    D
    |     
   1|2    
----+-----
   3|4   
    |
B   |    A


Now consider the grid squares 1,2,3,4. You will note that 1 is in fact
3, if you approach it from 2.  But it is 2 if you approach it from 3.

Paradox.

Of the squares labelled (1,2,3,4) only three of them are genuinely
distinct squares. (2,3,4) . Worse still, which square '1' represents
depends which direction you approach from.

Jules