[mkgmap-dev] vanishing segments

Fri Nov 28 22:27:07 GMT 2008

On Nov 27, 2008, at 23:52, Steve Ratcliffe wrote:
>> The resulting maps appear to have some segments missing. Do you think
>> this might be caused by clipping?
>
> Perhaps, but nothing should be clipped, should it?  There may be a bug
> where more is being clipped than should be.  This was recently the  
> case
> with polygons and a similar bug caused all polygons to be invisible.

I've looked at this some more... My guess would be that something is  
wrong with the Polyline bitstreams.

In my sample, there's two problematic roads. Each has three nodes (two  
segments), and one zoom level, the first is missing its last segment,  
while at the other level, the other one misses its last segment.  
Extending both roads by one segment, the two first segments were  
always there, but the new segments went missing as before. I also  
tried reversing one of the roads, and its problem went away.

I also tested the "node" bits in the bitstream (all to true, all to  
false, no difference). Shifting the first point of the road so it  
wasn't straight anymore also caused the last segment to show always.  
All missing segments I've observed were in straight roads.

One other thing: the background polygons aren't generated for .mp  
files because PolishMapDataSource doesn't call mapper.finish(). Adding  
this doesn't make a noticeable difference, though.

Cheers
Robert