[Freeciv-Dev] Re: (PR#3936) introducing native coordinates

[Jason Dorje Short <vze49r5w@xxxxxxxxxxx>]

Raimar Falke wrote:
> On Fri, Apr 11, 2003 at 04:11:14AM -0500, Jason Dorje Short wrote:
> > This makes some sense.  But please try to distinguish which map you are 
> > representing, and which coordinate system you are using.  For instance is a
>
>     THERE IS ONLY ONE COORDINATE SYSTEM. EACH TILE HAS EXACTLY ONE
>     PAIR (x,y).
>
> This is different to your idea but I think it makes it easier to
> understand. At least for me.
Ahh, well that explains part of the confusion [1].  The problem is, it 
doesn't work.  Your proposal is that we only use native coordinates, but 
square_iterate and other local functions cannot be implemented in these 
coordinates.  Similarly, global operations cannot be done in map 
coordinates.
The solution Ross and I have arrived at (over the past 2 years) is to 
have different coordinate systems.  Map coordinates remain unchanged 
from the way they are now.  Native coordinates are only used locally (in 
the code), for operations that they are better suited for.  Index 
coordinates are a 1-dimensional projection of native coordinates; their 
use remains unchanged.  Before you try to redefine the system we have 
agreed on, you should try to solve some of the problems it was 
originally designed to address.  This should probably include providing 
a working implementation (you may want to look at Ross's corecleanups 
patch, or the gen-topologies patch in freeciv-test to see how some of 
the other issues can be handled).
[1] The term "representation" and "coordinate system" are logically 
synonymous IMO.  When you show three different "representations" of the 
map, what you're really doing is showing three sets of tiles in the same 
representation.  This corresponds to the properties "real", "normal", 
etc., that apply to individual tiles (in any representation).  To achive 
masking we simply need a new property to distinguish masked from 
non-masked tiles; this is independent from the isometric-map issues that 
bring about the native/map coordinate split.
jason