[mkgmap-dev] [mkgmap-svn] Commit r4622: - use IsInUtil to do geometry calculations like insideness or outsideness: Allows to remove a lot of complex code but might be slower in some cases.

Thu Apr 1 12:08:43 BST 2021

Hi Gerd

I agree that calcContains should be changed as you suggest.

My view otherwise is that the code should be as simple as possible for
"correct" cases and not go to any trouble to detect overlapping
polygons in this phase, but just allocate them as [outer {inner}]+ and,
if the cutting logic has problems during its processing, then it can
flag errors.

Ticker 

On Thu, 2021-04-01 at 09:13 +0000, Gerd Petermann wrote:
> Hi Ticker,
> 
> I think the big question is what the code is expected to do with
> overlapping polygons. The code in trunk may or may not cut out an
> inner ring that overlaps the outer. If I got that right it was
> intended to ignore all rings which are overlapping, but I showed that
> this doesn't always work.
> 
> So, probably I should change the logic in the branch from
> return (x & IsInUtil.IN) != 0;
> to
> return (x & IsInUtil.OUT) == 0;
> 
> Means, calcContains() would return false if at least one point is not
> contained.
> 
> Gerd
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Gerd Petermann <gpetermann_muenchen at hotmail.com>
> Gesendet: Donnerstag, 1. April 2021 10:16
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r4622: - use IsInUtil
> to do geometry calculations like insideness or outsideness: Allows to
> remove a lot of complex code but might be slower in some cases.
> 
> Hi Ticker,
> 
> to be more prezise: Looking at the code in runIntersectionCheck() it
> may change the Bitset unfinishedPolys. Up to now I did not find a
> case where this happens, so I am tempted to remove the code, but I'd
> feel better if I would understand why it was coded before removing
> it.
> 
> Gerd
> 
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Gerd Petermann <gpetermann_muenchen at hotmail.com>
> Gesendet: Donnerstag, 1. April 2021 09:29
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r4622: - use IsInUtil
> to do geometry calculations like insideness or outsideness: Allows to
> remove a lot of complex code but might be slower in some cases.
> 
> Hi Ticker,
> 
> yes, that's what I plan to do. Right now I try to understand what is
> done with the data in collection intersectingPolygons.
> 
> Gerd
> 
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Donnerstag, 1. April 2021 09:25
> An: mkgmap-dev at lists.mkgmap.org.uk; mkgmap-svn at lists.mkgmap.org.uk
> Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r4622: - use IsInUtil
> to do geometry calculations like insideness or outsideness: Allows to
> remove a lot of complex code but might be slower in some cases.
> 
> Hi Gerd
> 
> Wouldn't it be more efficient to choose a point within a each polygon
> and then use IsInUtils.isPointInShape and the relative areas to test
> if
> this polygon is in others. The point could be the centre of the
> polygon, after checking isPointInShape == IN on itself, and, if not,
> make do with the closing point, or some trial and error moving from
> the
> closing point.
> 
> This also bypasses ambiguities cause by overlapping polygons in this
> phase of the logic.
> 
> Ticker
> 
> On Wed, 2021-03-31 at 15:56 +0100, svn commit wrote:
> > Version mkgmap-r4622 was committed by gerd on Wed, 31 Mar 2021
> > BRANCH: faster-mp
> > - use IsInUtil to do geometry calculations like insideness or
> > outsideness: Allows to remove a lot of complex code but might be
> > slower in some cases.
> > - document the poor completeness of collection
> > intersectingPolygons.
> > Probably will removed as well.
> > 
> > 
> > http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=462
> > 2
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