[Freeciv-Dev] Re: [RFC] Path finding interface

[Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>]

On Wed, 10 Apr 2002, Raimar Falke wrote:

> On Wed, Apr 10, 2002 at 12:14:44PM +0100, Gregory Berkolaiko wrote:
> > Read your latest path_finding3.h
> > Still not sure how get_next_path is supposed to be used?
> 
> You have the source and the destination. You pass the source to
> pf_get_map and the destination to pf_get_path_from_map. From
> pf_get_path_from_map you will get the path. After this you destroy the
> map.

Raimar, it would really help if you occasionally read the questions before 
writing the answer.  Please answer the original question.

> > Is it just very expensive version of my get_next_location?

And this one.  I mean: does get_next_path actually returns a path?

> > Is the map supposed to be ready by the time you call it?

Well, at least this question is answered.

> The map is constructed lazy. This means that pf_get_map will do no
> calculation and only setup the internal structs. Lets call one loop
> iteration of "while (get_from_mapqueue(&x, &y)) {" in
> really_generate_warmap an step. Than pf_get_path_from_map will execute
> as many steps as nessary to reach the
> destination. pf_get_next_path_from_map will do one step.

Ok, this makes sense.

[..]

> provide provide iterators not only for one step but also for multiple
> targets. Just thing of this example: you have a settler which want
> itself to add to some city. You have the start position and multiple
> destinations on the same continent. You don't have to calculate all
> costs to reach all tiles of the continent. You may use the simple
> iterator but pf_get_path_from_map will do this for you.

how will get_path do it?

G.