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[mkgmap-dev] Commit: r766: Write more of the *.mp-data.

From Alexander Atanasov aatanasov at gmail.com on Mon Dec 8 12:12:58 GMT 2008

Hi, Robert!

On 12/6/08, Robert Vollmert <rvollmert-lists at gmx.net> wrote:

> > They should be even simplified as a signle point, that is polyline
> > with point and one zero  delta. And that segment is in net.
> >
> I'm afraid I don't understand this. In the proper maps, every road in NET
> links to a polyline in a low zoom level that's in fact just a point?

Okay, i'll try to explain. I know that some roads(polylines) are
encoded like this,
and i was wondering why? So when you draw the map you draw the objects
but when you draw nodes you need to get from the segments to the polylines.
To do so in NET you have segments per level, get the zoom level
find the segments and draw them to display the route.
If they are missing you don't know what to draw so short roads become points.

big zoom
long road                                     long road
---------------------\                  /----------------------------
                           \ s1           /
                            \ ----------
small zoom
long road                                  long road
-----------------                       ----------------------

so if s1 and s2 are missing you won't see the curve but just
a stright line. But if you have s1 and s2 as polylines with one point
it can be drawn.

small zoom
long road                                  long road
-----------------                       ----------------------
                     P(s1)           P(s2)

have fun,

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