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

[Jason Dorje Short <vze49r5w@xxxxxxxxxxx>]

Raimar Falke wrote:
> On Mon, Apr 14, 2003 at 11:02:28AM -0500, Jason Dorje Short wrote:
> > Raimar Falke wrote:
> > > On Sun, Apr 13, 2003 at 05:37:59PM -0500, Jason Dorje Short wrote:
> > I'm not sure.  Certainly 
> > there are some additional (non-mapview-specific) ones in mapview.
>
> > Conversely, if we use map coordinates as standard there are just a few 
> > places that need to convert to native coordinates.  These include a few 
> > map.c backend functions (normalize_map_pos, map_distance_vector, 
> > rand_map_pos, map_to_index_pos, index_to_map_pos) as well as a very few 
> > pieces of user code (savegames, map debug output).
>
> So we both say that our changes are minimal.
Yep.  I'm not against the idea of using native coordinates as standard. 
 I'm just not willing to track down all the places that need to be 
fixed for it, since I've already spent 2 years doing it the other way.
> > > - mapview: is reduced to one file (mapview_common) AFAIK
> > Don't just lump in everything in mapview.c and mapview_common.c into 
> > "mapview" and write it off.  mapview does have some very specialized 
> > needs (like clipping the window), but also some generalized ones as well 
> > (like rectangle_iterate).
>
> You agree that all this should and can be done in mapview_common?!
>
> I also said in the past that the mapview_common change won't be easy.
But again you're lumping all this stuff together.  There is a discrete 
set of changes:
- clip_mapview_window - localized and ugly.  Does not relate to the 
current discussion.
- mapview scrolling - non-localized and ugly.  Does not relate to the 
current discussion.
- overview window: non-localized, but fairly low-impact.

- unnormalize_map_pos: localized and complicated.  Does not relate to 
the current discussion.
- Other misc changes.  These generally do relate to the current 
discussion.  For instance under your system, all of the mapview 
iterations need to be done in map coordinates and need a manual 
conversion.  This is not localized, and cannot be written off as "part 
of that mapview change" since it relates directly to this discussion.
> Let me create some code so that we can have some facts. Hopefully this
> week.
>
> Is there an implementation of your approach which is complete? For
> measure of speed and general impact this doesn't have to support
> mapview.
Excellent.  See the gen-topologies patch in freeciv-test.  It is 
out-of-date for current CVS (by about 2 weeks, I think - I have an 
updated patch locally).
You do need to support mapview.  Most of the mapview code can remain 
unchanged (note, clip_mapview_window and mapview scrolling do not work 
perfectly).  What you will need to fix is the fact that mapview deals 
exclusively in map coordinates, so you'll need to convert to/from native 
coordinates all over the place.
But you can drop all of the existing map<->native conversion operations, 
so this will approximately balance out.  This includes huge quantities 
of mapgen.c, some stuff in map.c, and some scattered other places.
Compared to mapgen and mapview, everything else is tiny.  So as a 
measure of "general impact" these two are very significant.
jason