[geos-devel] OverlayOp JTS port

[Obe, Regina]

I apologize for the barrage of questions.  As far as I can tell the 
OverlayOp.cpp is vintage JTS 1.7 (which I think is same as the JTS 1.9 for this class)

except it has the additional calls of

checkObviouslyWrongResult() - which most of that code looks like it would never
be called because of the #ifdefs except for the  

assert(resultGeom); 
UNREFERENCED_PARAMETER(opCode); (have no clue what this does)

and also a 
elevationMatrix->elevate(resultGeom);

which looks like will get called since USE_ELEVATION_MATRIX 1.

Is the elevationMatrix designed to deal with 3d geometries?  Didn't realize 
Union actually works with those, but then I never tried it with 3d.

So I'm a little puzzled why these 2 extra function calls since I always thought
GEOS was at best on par with JTS?

Thanks,
Regina

-----Original Message-----
From: geos-devel-bounces at lists.osgeo.org on behalf of Obe, Regina
Sent: Wed 9/17/2008 9:26 AM
To: GEOS Development List
Subject: [geos-devel] OverlayOp JTS port
 
I'm looking at the operation.overlay.OverlayOp in geos trunk

In the header it says
Last port: operation/overlay/OverlayOp.java rev. 1.23

But I don't believe this to be right since when I compare the
computeOverlay methods
against 1.2 and 1.3 versions of JTS codebase, it has an additional
EdgeNodingValidator check which wasn't introduced until later versions
of JTS.

So I'm wondering is the OverlayOp.cpp a mix of JTS versions or is the
comment above just plain wrong.

It also has a checkObviouslyWrongResult() check at the end of
computerOverlay which I haven't figured out which version that was
introduced in JTS (its not in 1.2,1.3, or 1.9).  Is this a GEOS specific
check that has no JTS equivalent?

Thanks,
Regina
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