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

[Jason Dorje Short <vze49r5w@xxxxxxxxxxx>]

Raimar Falke wrote:
> On Sun, Apr 06, 2003 at 04:08:42PM -0500, Jason Dorje Short wrote:
> > Raimar Falke wrote:
> > The directions *are* rotated, yes.  Note that the DIR_D[XY] arrays would 
> > have to be changed for native coordinates, and they would be different 
> > between iso and non-iso maps.  The conclusion is that native coordinates 
> > are not good for local operations like moving in a single direction, and 
> > these are best done in map coordinates.
>
> So what do you think about the following proposal: 
>  - we leave the storage of the map tiles unchanged
>  - we add an iso bit to the map struct (save and transfer it)
>  - we change DIRSTEP, MAPSTEP, is_cardinal (trivial)
>  - we doesn't need to change is_normal_map_pos, is_real_map_pos,
>  whole_map_iterate and is_border_map_pos
>  - we change normalize_map_pos (seems trivial)
>  - we change the mapview to do the rotation (non-trivial)
>
> How does this differ from the use of iso-maps you have in mind? What
> did I miss? For the mapview changes the notation of native coordinates
> help a lot but these is limited to only one set of files
> (mapview_common).
I don't quite understand your suggestion.  Are you saying all operations 
be done in native coordinates, and "map" coordinates be dropped?  The 
problem with this is most local operations become much more difficult, 
since the local tile geometry is not preserved.  For instance 
adjc_dir_iterate (via DIR_D[XY]), square_iterate, map_to_city_map, 
map_distance, etc.  This will require many changes to the code, and will 
be error-prone.
Ross any my idea is that the map struct gets three bits of information: 
xwrap, ywrap, and iso.  The iso bit only needs to be checked in a few 
places: map_to_native_pos, native_to_map_pos, unnormalize_map_pos, and 
clip_mapview_window (or whatever this operation ends up being called).
The xwrap and ywrap bit is checked in a few other places: particularly 
normalize_map_pos nearest_real_pos.
Native positions are only used for a few operations (the vast majority 
continue to use map or indexed positions):
  - whole_map_iterate
  - gamelog
  - savegames
  - mapgen, all over the place
  - normalize_map_pos, nearest_real_pos
  - the map overview

jason