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

[Jason Dorje Short <vze49r5w@xxxxxxxxxxx>]

Raimar Falke wrote:
> On Thu, Apr 24, 2003 at 08:58:16AM -0500, Jason Dorje Short wrote:
> > > > > - how can mapview code done in an easier way (IMHO with an
> > > > > intermediate form)
> > > > Again you are lumping a whole collection of unrelated operations into 
> > > > one term.
> > > This is a bit terse.
> > >
> > > I'm trying to split unnormalize_map_pos into two operations. First the
> > > wrapping and than the rotating and scaling to pixels. What is your
> > > opinion?
> > unnormalize_map_pos is only a small part of the mapview code - just a 
> > single part of one function (map_to_canvas_pos).  It does the wrapping 
> > part only; the rotating and scaling to pixels is done separately by 
> > map_to_canvas_pos.  So this split is already in place...
>
> If it only does the wrapping it is complex. I have to look further
> into this.
If you're willing to sacrifice correctness you can write something 
simpler by determining the map_distance_vector from the center tile of 
the mapview_canvas.  However it will end up putting some tiles 
off-canvas when they could rightfully be wrapped directly onto the canvas.
Something truly simple could be written with basic wrapping, ignoring 
the iso nature of the mapview.  This is what the current code does, but 
it has a signficant bug: even if you make the canvas infinitely large 
some tiles will never be shown.
For full correctness, unnormalize_map_pos should take a width and height 
parameter.  This also potentially allows multiple drawing of tiles. 
However, this makes it even more complicated and only helps in a few 
pathological cases.
jason