Subject: Re: [boost] [Review] We're halfway through the GGL review
From: Barend Gehrels (barend_at_[hidden])
Date: 2009-11-15 17:18:24
> Maybe you can use them in one of the examples, to make things clearer.
Sure, that makes sense. We'll do that.
>> Therefore, union and intersection work with output iterators. So:
>> union_inserter(p1, p2, std::back_inserter(ps1));
> Hm, I tried:
> #include <boost/ggl/ggl.hpp>
> #include <boost/ggl/geometries/cartesian3d.hpp>
> #include <boost/ggl/multi/geometries/multi_polygon.hpp>
> #include <boost/ggl/algorithms/union.hpp>
> typedef multi_polygon<polygon_3d> polygon_set_3d;
> polygon_set_3d ps;
> polygon_3d poly1;
> polygon_3d poly2;
> union_inserter(poly1, poly2, std::back_inserter(ps));
There are two things:
- I forgot one thing, sorry, the inserter-versions always have their
output type as a required template parameter. That one can, AFAIK, not
be deduced from the output iterator. And it might be a different type of
the input polygons. If someone knows if that is possible somehow, I
would be happy to know. So it should be: union_inserter<polygon_2d>(p1,
- You're using the 3d polygons here. The union would make a 2D
union-operation then of your 3D polygons (so polygons with for all
vertices a height). It would ignore the third dimension (because it is
not a polyhedron union). I just tried it, to not give you again wrong
information. But it is not working yet like this, a.o. because the
functions convert, area and point-in-polygon which should support 3D
then. Especially area implementation would probably be different for 3D.
Though it is used as a helper-function in the union, so its usage could
> Besides I would probably not call it union_ but geometric_union or
> some such, but thats just personal preference.
Yes, but it is already in the namespace ggl. We thought that union_
conforms to boost/mpl conventions (not_, if_)
> For each class/function add a short usage example including all
> relevant includes (something short like the snipplet above)
> This makes it immediately clear how things work together.
That makes also sense, thanks.
Boost list run by bdawes at acm.org, david.abrahams at rcn.com, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk