[mkgmap-dev] [PATCH v1] Decide in style file if a way is closed automatically

Fri Oct 26 22:34:14 BST 2012

Steve wrote:
> I don't much like the idea of adding two tags to every single way.
> 
> > + // the way may be closed automatically because both endpoints are
> > outside the bbox
> > + // set a tag so that these ways can be ignored in the style rules
> > + way.addTag("mkgmap:autoclosing", "true");
> 
> It seems to me that setting this is all that is required. It will only
> affect relatively few ways, and you can test for tag existence rather
> than having to know/remember if you should test against 'true',
> 'True', 'yes', '1' or whatever.

I agree Steve, 
mkgmap:autoclosing=true was indeed the only tag that I needed to render those 'problematic' polygons.

> But apart from that, the main thing is that any rule that uses this
> will
> still be guessing -- what if it really was a polygon? Then you
> will have a missing area of water.

In my test case I haven't seen those issues yet. Even this canal which was split in two tiles
http://www.openstreetmap.org/browse/way/53011144 was rendered as polygon, maybe because the first node
was just within the overlap range (3000) of the other tile? 
So it would only be broken if it was a rather large polygon.
But fortunately most of the items were relatively small polygons.

> I think we can do better though. 
(...)
> Then 'is_closed()' might be a good candidate for a style
> function?

Well, if this doesnt take too much calculation time, please go ahead :-)