123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164 |
- // Boost.Geometry (aka GGL, Generic Geometry Library)
- // Copyright (c) 2019 Barend Gehrels, Amsterdam, the Netherlands.
- // Use, modification and distribution is subject to the Boost Software License,
- // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_DISTANCE_MEASURE_HPP
- #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_DISTANCE_MEASURE_HPP
- #include <boost/geometry/core/access.hpp>
- #include <boost/geometry/core/coordinate_system.hpp>
- #include <boost/geometry/core/coordinate_type.hpp>
- #include <boost/geometry/arithmetic/infinite_line_functions.hpp>
- #include <boost/geometry/algorithms/detail/make/make.hpp>
- #include <boost/geometry/util/select_coordinate_type.hpp>
- #include <cmath>
- namespace boost { namespace geometry
- {
- #ifndef DOXYGEN_NO_DETAIL
- namespace detail
- {
- template <typename T>
- struct distance_measure
- {
- T measure;
- distance_measure()
- : measure(T())
- {}
- bool is_small() const { return false; }
- bool is_zero() const { return false; }
- bool is_positive() const { return false; }
- bool is_negative() const { return false; }
- };
- template <typename T>
- struct distance_measure_floating
- {
- T measure;
- distance_measure_floating()
- : measure(T())
- {}
- // Returns true if the distance measure is small.
- // This is an arbitrary boundary, to enable some behaviour
- // (for example include or exclude turns), which are checked later
- // with other conditions.
- bool is_small() const { return std::abs(measure) < 1.0e-3; }
- // Returns true if the distance measure is absolutely zero
- bool is_zero() const { return measure == 0.0; }
- // Returns true if the distance measure is positive. Distance measure
- // algorithm returns positive value if it is located on the left side.
- bool is_positive() const { return measure > 0.0; }
- // Returns true if the distance measure is negative. Distance measure
- // algorithm returns negative value if it is located on the right side.
- bool is_negative() const { return measure < 0.0; }
- };
- template <>
- struct distance_measure<long double>
- : public distance_measure_floating<long double> {};
- template <>
- struct distance_measure<double>
- : public distance_measure_floating<double> {};
- template <>
- struct distance_measure<float>
- : public distance_measure_floating<float> {};
- } // detail
- namespace detail_dispatch
- {
- // TODO: this is effectively a strategy, but for internal usage.
- // It might be moved to the strategies folder.
- template <typename CalculationType, typename CsTag>
- struct get_distance_measure
- : not_implemented<CsTag>
- {};
- template <typename CalculationType>
- struct get_distance_measure<CalculationType, cartesian_tag>
- {
- typedef detail::distance_measure<CalculationType> result_type;
- template <typename SegmentPoint, typename Point>
- static result_type apply(SegmentPoint const& p1, SegmentPoint const& p2,
- Point const& p)
- {
- // Get the distance measure / side value
- // It is not a real distance and purpose is
- // to detect small differences in collinearity
- typedef model::infinite_line<CalculationType> line_type;
- line_type const line = detail::make::make_infinite_line<CalculationType>(p1, p2);
- result_type result;
- result.measure = arithmetic::side_value(line, p);
- return result;
- }
- };
- template <typename CalculationType>
- struct get_distance_measure<CalculationType, spherical_tag>
- {
- typedef detail::distance_measure<CalculationType> result_type;
- template <typename SegmentPoint, typename Point>
- static result_type apply(SegmentPoint const& , SegmentPoint const& ,
- Point const& )
- {
- // TODO, optional
- result_type result;
- return result;
- }
- };
- template <typename CalculationType>
- struct get_distance_measure<CalculationType, geographic_tag>
- : get_distance_measure<CalculationType, spherical_tag> {};
- } // namespace detail_dispatch
- namespace detail
- {
- // Returns a (often very tiny) value to indicate its side, and distance,
- // 0 (absolutely 0, not even an epsilon) means collinear. Like side,
- // a negative means that p is to the right of p1-p2. And a positive value
- // means that p is to the left of p1-p2.
- template <typename cs_tag, typename SegmentPoint, typename Point>
- static distance_measure<typename select_coordinate_type<SegmentPoint, Point>::type>
- get_distance_measure(SegmentPoint const& p1, SegmentPoint const& p2, Point const& p)
- {
- return detail_dispatch::get_distance_measure
- <
- typename select_coordinate_type<SegmentPoint, Point>::type,
- cs_tag
- >::apply(p1, p2, p);
- }
- } // namespace detail
- #endif // DOXYGEN_NO_DETAIL
- }} // namespace boost::geometry
- #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_DISTANCE_MEASURE_HPP
|