Geometry Boost List: [geometry] intersection_tolerance

From: Giorgino R (giorginor21_at_[hidden])
Date: 2023-03-27 13:23:57

Hi there,

I know that this may has been raised again; however, I can't find any clear
answer/solution so far. Does anyone know what is the best way to overwrite
the tolerance for linestring-to-linestring and segment-to-segment
intersection(s) in boost geometry?

For example, what is the best way to get such an intersection

    using point2d = boost::geometry::model::point<double, 2,
boost::geometry::cs::cartesian>;
    using linestring = boost::geometry::model::linestring<point2d>;

    linestring linestring1{ {2000.0, 0.0}, {4000.0, 0.0} };
    linestring linestring2{ {1000.0, 0.0}, {1999.999999999, 0.0} };

    std::vector<point2d> result;

    boost::geometry::intersection(linestring1, linestring2, result);

I understand that by default boost uses the
std::numeric_limits<double>::epsilon for point of type double. I can also
see that under utils/math there is an equal::apply function for such
comparisons. When I specialise this function for my point types and I add
the preprocessor macro "BOOST_GEOMETRY_NO_ROBUSTNESS", I get the
intersection. Is there any better way to accomplish this? Can I do
something similar with a rescaling policy? I tried to find something
relevant in the docs but I have had no luck (I would not like to specialise
anything under boost::geometry::detail).

Furthermore, is there any strategy and/or way to calculate the
perpendicular distance between two linestrings? Or I have to work it out by
myself (it should not be so difficult I just wonder whether there is
strategy already inside boost geometry)?

Many thanks in advance,

Giorgio