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

[Jason Dorje Short <vze49r5w@xxxxxxxxxxx>]

Raimar Falke wrote:
> On Mon, Apr 07, 2003 at 01:06:17PM -0500, Jason Dorje Short wrote:
>
> > 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.
>
> My suggestion is to leave a lot of the code untouched (see the list
> above). A layer is needed to express the iso-map. But only a thin
> layer. I _think_ that this layer will only consists of the dir
> transformation. So we would have a "normal map" direction and a
> (map)view direction and the relation is either identity (non-iso maps)
> or dir_cw (iso-maps). This layer is thin and a lot thinner than the
> layer you describe. I'm not sure that my layer is complete. So I'm
> still asking for all the effects of the iso-map. But if it is only
> rotating is should be not much more.
Err, you didn't answer my question.  But I think you have not thought 
through things fully.  How would you implement:
  - square_map_iterate
  - map_distance/real_map_distance/sq_map_distance
    (presumably map_distance_vector is easy)
  - canvas_to_map_pos/map_to_canvas_pos (ignoring wrapping issues)
  - show_city_descriptions/update_map_canvas

it's not just a question of how many places need to be touched, but of 
how difficult/ugly/unmaintainable the new code will be.
jason