Chris@16: // Boost.Geometry (aka GGL, Generic Geometry Library)
Chris@16: 
Chris@16: // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
Chris@16: // Copyright (c) 2009-2012 Barend Gehrels, Amsterdam, the Netherlands.
Chris@16: 
Chris@16: // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
Chris@16: // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software License,
Chris@16: // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP
Chris@16: #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP
Chris@16: 
Chris@101: #include <boost/geometry/algorithms/detail/distance/interface.hpp>
Chris@101: #include <boost/geometry/algorithms/detail/distance/point_to_geometry.hpp>
Chris@16: #include <boost/geometry/arithmetic/arithmetic.hpp>
Chris@16: #include <boost/geometry/util/select_most_precise.hpp>
Chris@16: #include <boost/geometry/strategies/centroid.hpp>
Chris@16: #include <boost/geometry/strategies/default_distance_result.hpp>
Chris@16: 
Chris@16: // Helper geometry
Chris@16: #include <boost/geometry/geometries/point.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost { namespace geometry
Chris@16: {
Chris@16: 
Chris@16: namespace strategy { namespace centroid
Chris@16: {
Chris@16: 
Chris@16: namespace detail
Chris@16: {
Chris@16: 
Chris@16: template <typename Type, std::size_t DimensionCount>
Chris@16: struct weighted_length_sums
Chris@16: {
Chris@16:     typedef typename geometry::model::point
Chris@16:         <
Chris@16:             Type, DimensionCount,
Chris@16:             cs::cartesian
Chris@16:         > work_point;
Chris@16: 
Chris@16:     Type length;
Chris@16:     work_point average_sum;
Chris@16: 
Chris@16:     inline weighted_length_sums()
Chris@16:         : length(Type())
Chris@16:     {
Chris@16:         geometry::assign_zero(average_sum);
Chris@16:     }
Chris@16: };
Chris@16: }
Chris@16: 
Chris@16: template
Chris@16: <
Chris@16:     typename Point,
Chris@16:     typename PointOfSegment = Point
Chris@16: >
Chris@16: class weighted_length
Chris@16: {
Chris@16: private :
Chris@16:     typedef typename select_most_precise
Chris@16:         <
Chris@16:             typename default_distance_result<Point>::type,
Chris@16:             typename default_distance_result<PointOfSegment>::type
Chris@16:         >::type distance_type;
Chris@16: 
Chris@16: public :
Chris@16:     typedef detail::weighted_length_sums
Chris@16:         <
Chris@16:             distance_type,
Chris@16:             geometry::dimension<Point>::type::value
Chris@16:         > state_type;
Chris@16: 
Chris@16:     static inline void apply(PointOfSegment const& p1,
Chris@16:             PointOfSegment const& p2, state_type& state)
Chris@16:     {
Chris@16:         distance_type const d = geometry::distance(p1, p2);
Chris@16:         state.length += d;
Chris@16: 
Chris@16:         typename state_type::work_point weighted_median;
Chris@16:         geometry::assign_zero(weighted_median);
Chris@16:         geometry::add_point(weighted_median, p1);
Chris@16:         geometry::add_point(weighted_median, p2);
Chris@16:         geometry::multiply_value(weighted_median, d/2);
Chris@16:         geometry::add_point(state.average_sum, weighted_median);
Chris@16:     }
Chris@16: 
Chris@16:     static inline bool result(state_type const& state, Point& centroid)
Chris@16:     {
Chris@16:         distance_type const zero = distance_type();
Chris@16:         if (! geometry::math::equals(state.length, zero))
Chris@16:         {
Chris@16:             assign_zero(centroid);
Chris@16:             add_point(centroid, state.average_sum);
Chris@16:             divide_value(centroid, state.length);
Chris@16:             return true;
Chris@16:         }
Chris@16: 
Chris@16:         return false;
Chris@16:     }
Chris@16: 
Chris@16: };
Chris@16: 
Chris@16: #ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
Chris@16: 
Chris@16: namespace services
Chris@16: {
Chris@16: 
Chris@16: 
Chris@16: // Register this strategy for linear geometries, in all dimensions
Chris@16: 
Chris@16: template <std::size_t N, typename Point, typename Geometry>
Chris@16: struct default_strategy
Chris@16: <
Chris@16:     cartesian_tag,
Chris@16:     linear_tag,
Chris@16:     N,
Chris@16:     Point,
Chris@16:     Geometry
Chris@16: >
Chris@16: {
Chris@16:     typedef weighted_length
Chris@16:         <
Chris@16:             Point,
Chris@16:             typename point_type<Geometry>::type
Chris@16:         > type;
Chris@16: };
Chris@16: 
Chris@16: 
Chris@16: } // namespace services
Chris@16: 
Chris@16: 
Chris@16: #endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
Chris@16: 
Chris@16: 
Chris@16: }} // namespace strategy::centroid
Chris@16: 
Chris@16: 
Chris@16: }} // namespace boost::geometry
Chris@16: 
Chris@16: 
Chris@16: #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP