Hi Gerd ShapeSplitter only works on a single-path shape. Considering the act of splitting a shape with a single line, you are left with a list of lines that start and end on the divider. These lines don't cross each other unless the polygon was self-intersecting which is not allowed. Then, just considering one side of the divider, the complexities of how the other side contorted to define multiple holes in a shape, and shapes in a hole can all be ignored. Lines going one way relating to the dividing line define the outer edge of a shape, and if the shape has direct holes, they must go the other way. I think the above is true for any non-self-intersecting polygon. ShapeSplitter has to resort to using the sign of the area of a shape defined by one of these lines and the divider only when multiple lines start and end at the same point. It can handle a shape and hole going through a single dividing point, so can easily cope with dividing a polygon where there is a single cut to an inner hole. Without self-intersection, if the dominant direction of the polygon is, say, anti-clockwise, then the hole must be clockwise. Does this make sense? Ticker On Tue, 2017-01-31 at 15:41 +0000, Gerd Petermann wrote:
Hi Ticker,
thanks, will look again later. I am working on a patch for the MultiPolygonCutter. It works without java.awt.geom.Area, the basic idea is to connect shapes where they are close to each other. I've tried that in 2012, maybe I get it working now. One problem that I've noticed: The code in ShapeSplitter seems to consider some shapes as self -intersecting when the connected inner ways are clockwise (or not clockwise, not sure which one causes trouble). I assume you coded this because the shapes produced by java.awt.geom.Area are like that, outer shape is one direction and inner shapes are in the other direction. I have some problems with this behaviour, is it needed ? For now I found a work around by reversing the ways so that they are ordered. Attached is a patch with what I coded so far, open problems are mp-rels at tile boundaries and performance. Be careful, the code contains lots of GPXCreator statements and other debug code.
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Dienstag, 31. Januar 2017 16:26:41 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] Multipolygon-Relation checks in mkgmap
Hi Gerd
I've think I've finished making all the changes I want to do at the moment - It seems to work nicely. Sometime can you merge the branch back if you are happy with it.
Thanks Ticker
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