| // Boost.Geometry (aka GGL, Generic Geometry Library) |
| |
| // Copyright (c) 2008-2011 Bruno Lalande, Paris, France. |
| // Copyright (c) 2008-2011 Barend Gehrels, Amsterdam, the Netherlands. |
| // Copyright (c) 2009-2011 Mateusz Loskot, London, UK. |
| |
| // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library |
| // (geolib/GGL), copyright (c) 1995-2010 Geodan, 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_STRATEGIES_CARTESIAN_DISTANCE_PROJECTED_POINT_HPP |
| #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_DISTANCE_PROJECTED_POINT_HPP |
| |
| |
| #include <boost/concept_check.hpp> |
| #include <boost/mpl/if.hpp> |
| #include <boost/type_traits.hpp> |
| |
| #include <boost/geometry/core/access.hpp> |
| #include <boost/geometry/core/point_type.hpp> |
| |
| #include <boost/geometry/algorithms/convert.hpp> |
| #include <boost/geometry/arithmetic/arithmetic.hpp> |
| #include <boost/geometry/arithmetic/dot_product.hpp> |
| |
| #include <boost/geometry/strategies/tags.hpp> |
| #include <boost/geometry/strategies/distance.hpp> |
| #include <boost/geometry/strategies/default_distance_result.hpp> |
| #include <boost/geometry/strategies/cartesian/distance_pythagoras.hpp> |
| |
| #include <boost/geometry/util/select_coordinate_type.hpp> |
| |
| // Helper geometry (projected point on line) |
| #include <boost/geometry/geometries/point.hpp> |
| |
| |
| namespace boost { namespace geometry |
| { |
| |
| |
| namespace strategy { namespace distance |
| { |
| |
| |
| /*! |
| \brief Strategy for distance point to segment |
| \ingroup strategies |
| \details Calculates distance using projected-point method, and (optionally) Pythagoras |
| \author Adapted from: http://geometryalgorithms.com/Archive/algorithm_0102/algorithm_0102.htm |
| \tparam Point \tparam_point |
| \tparam PointOfSegment \tparam_segment_point |
| \tparam CalculationType \tparam_calculation |
| \tparam Strategy underlying point-point distance strategy |
| \par Concepts for Strategy: |
| - cartesian_distance operator(Point,Point) |
| \note If the Strategy is a "comparable::pythagoras", this strategy |
| automatically is a comparable projected_point strategy (so without sqrt) |
| |
| \qbk{ |
| [heading See also] |
| [link geometry.reference.algorithms.distance.distance_3_with_strategy distance (with strategy)] |
| } |
| |
| */ |
| template |
| < |
| typename Point, |
| typename PointOfSegment = Point, |
| typename CalculationType = void, |
| typename Strategy = pythagoras<Point, PointOfSegment, CalculationType> |
| > |
| class projected_point |
| { |
| public : |
| typedef typename strategy::distance::services::return_type<Strategy>::type calculation_type; |
| |
| private : |
| |
| // The three typedefs below are necessary to calculate distances |
| // from segments defined in integer coordinates. |
| |
| // Integer coordinates can still result in FP distances. |
| // There is a division, which must be represented in FP. |
| // So promote. |
| typedef typename promote_floating_point<calculation_type>::type fp_type; |
| |
| // A projected point of points in Integer coordinates must be able to be |
| // represented in FP. |
| typedef model::point |
| < |
| fp_type, |
| dimension<PointOfSegment>::value, |
| typename coordinate_system<PointOfSegment>::type |
| > fp_point_type; |
| |
| // For convenience |
| typedef fp_point_type fp_vector_type; |
| |
| // We have to use a strategy using FP coordinates (fp-type) which is |
| // not always the same as Strategy (defined as point_strategy_type) |
| // So we create a "similar" one |
| typedef typename strategy::distance::services::similar_type |
| < |
| Strategy, |
| Point, |
| fp_point_type |
| >::type fp_strategy_type; |
| |
| public : |
| |
| inline calculation_type apply(Point const& p, |
| PointOfSegment const& p1, PointOfSegment const& p2) const |
| { |
| assert_dimension_equal<Point, PointOfSegment>(); |
| |
| /* |
| Algorithm [p1: (x1,y1), p2: (x2,y2), p: (px,py)] |
| VECTOR v(x2 - x1, y2 - y1) |
| VECTOR w(px - x1, py - y1) |
| c1 = w . v |
| c2 = v . v |
| b = c1 / c2 |
| RETURN POINT(x1 + b * vx, y1 + b * vy) |
| */ |
| |
| // v is multiplied below with a (possibly) FP-value, so should be in FP |
| // For consistency we define w also in FP |
| fp_vector_type v, w; |
| |
| geometry::convert(p2, v); |
| geometry::convert(p, w); |
| subtract_point(v, p1); |
| subtract_point(w, p1); |
| |
| Strategy strategy; |
| boost::ignore_unused_variable_warning(strategy); |
| |
| calculation_type const zero = calculation_type(); |
| fp_type const c1 = dot_product(w, v); |
| if (c1 <= zero) |
| { |
| return strategy.apply(p, p1); |
| } |
| fp_type const c2 = dot_product(v, v); |
| if (c2 <= c1) |
| { |
| return strategy.apply(p, p2); |
| } |
| |
| // See above, c1 > 0 AND c2 > c1 so: c2 != 0 |
| fp_type const b = c1 / c2; |
| |
| fp_strategy_type fp_strategy |
| = strategy::distance::services::get_similar |
| < |
| Strategy, Point, fp_point_type |
| >::apply(strategy); |
| |
| fp_point_type projected; |
| geometry::convert(p1, projected); |
| multiply_value(v, b); |
| add_point(projected, v); |
| |
| //std::cout << "distance " << dsv(p) << " .. " << dsv(projected) << std::endl; |
| |
| return fp_strategy.apply(p, projected); |
| } |
| }; |
| |
| #ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS |
| namespace services |
| { |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct tag<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| typedef strategy_tag_distance_point_segment type; |
| }; |
| |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct return_type<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| typedef typename projected_point<Point, PointOfSegment, CalculationType, Strategy>::calculation_type type; |
| }; |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct strategy_point_point<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| typedef Strategy type; |
| }; |
| |
| |
| template |
| < |
| typename Point, |
| typename PointOfSegment, |
| typename CalculationType, |
| typename Strategy, |
| typename P1, |
| typename P2 |
| > |
| struct similar_type<projected_point<Point, PointOfSegment, CalculationType, Strategy>, P1, P2> |
| { |
| typedef projected_point<P1, P2, CalculationType, Strategy> type; |
| }; |
| |
| |
| template |
| < |
| typename Point, |
| typename PointOfSegment, |
| typename CalculationType, |
| typename Strategy, |
| typename P1, |
| typename P2 |
| > |
| struct get_similar<projected_point<Point, PointOfSegment, CalculationType, Strategy>, P1, P2> |
| { |
| static inline typename similar_type |
| < |
| projected_point<Point, PointOfSegment, CalculationType, Strategy>, P1, P2 |
| >::type apply(projected_point<Point, PointOfSegment, CalculationType, Strategy> const& ) |
| { |
| return projected_point<P1, P2, CalculationType, Strategy>(); |
| } |
| }; |
| |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct comparable_type<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| // Define a projected_point strategy with its underlying point-point-strategy |
| // being comparable |
| typedef projected_point |
| < |
| Point, |
| PointOfSegment, |
| CalculationType, |
| typename comparable_type<Strategy>::type |
| > type; |
| }; |
| |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct get_comparable<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| typedef typename comparable_type |
| < |
| projected_point<Point, PointOfSegment, CalculationType, Strategy> |
| >::type comparable_type; |
| public : |
| static inline comparable_type apply(projected_point<Point, PointOfSegment, CalculationType, Strategy> const& ) |
| { |
| return comparable_type(); |
| } |
| }; |
| |
| |
| template <typename Point, typename PointOfSegment, typename CalculationType, typename Strategy> |
| struct result_from_distance<projected_point<Point, PointOfSegment, CalculationType, Strategy> > |
| { |
| private : |
| typedef typename return_type<projected_point<Point, PointOfSegment, CalculationType, Strategy> >::type return_type; |
| public : |
| template <typename T> |
| static inline return_type apply(projected_point<Point, PointOfSegment, CalculationType, Strategy> const& , T const& value) |
| { |
| Strategy s; |
| return result_from_distance<Strategy>::apply(s, value); |
| } |
| }; |
| |
| |
| // Get default-strategy for point-segment distance calculation |
| // while still have the possibility to specify point-point distance strategy (PPS) |
| // It is used in algorithms/distance.hpp where users specify PPS for distance |
| // of point-to-segment or point-to-linestring. |
| // Convenient for geographic coordinate systems especially. |
| template <typename Point, typename PointOfSegment, typename Strategy> |
| struct default_strategy<segment_tag, Point, PointOfSegment, cartesian_tag, cartesian_tag, Strategy> |
| { |
| typedef strategy::distance::projected_point |
| < |
| Point, |
| PointOfSegment, |
| void, |
| typename boost::mpl::if_ |
| < |
| boost::is_void<Strategy>, |
| typename default_strategy |
| < |
| point_tag, Point, PointOfSegment, |
| cartesian_tag, cartesian_tag |
| >::type, |
| Strategy |
| >::type |
| > type; |
| }; |
| |
| |
| } // namespace services |
| #endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS |
| |
| |
| }} // namespace strategy::distance |
| |
| |
| }} // namespace boost::geometry |
| |
| |
| #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_DISTANCE_PROJECTED_POINT_HPP |