Added boost header

test/external/boost/geometry/strategies/cartesian/centroid_bashein_detmer.hpp

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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
+// Copyright (c) 2008-2011 Bruno Lalande, Paris, France.
+// 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_CENTROID_BASHEIN_DETMER_HPP
+#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_BASHEIN_DETMER_HPP
+
+
+#include <boost/mpl/if.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+#include <boost/type_traits.hpp>
+
+#include <boost/geometry/core/coordinate_type.hpp>
+#include <boost/geometry/core/point_type.hpp>
+#include <boost/geometry/strategies/centroid.hpp>
+#include <boost/geometry/util/select_coordinate_type.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+// Note: when calling the namespace "centroid", it sometimes,
+// somehow, in gcc, gives compilation problems (confusion with function centroid).
+
+namespace strategy { namespace centroid
+{
+
+
+
+/*!
+\brief Centroid calculation using algorith Bashein / Detmer
+\ingroup strategies
+\details Calculates centroid using triangulation method published by
+    Bashein / Detmer
+\tparam Point point type of centroid to calculate
+\tparam PointOfSegment point type of segments, defaults to Point
+\par Concepts for Point and PointOfSegment:
+- specialized point_traits class
+\author Adapted from  "Centroid of a Polygon" by
+    Gerard Bashein and Paul R. Detmer<em>,
+in "Graphics Gems IV", Academic Press, 1994</em>
+\par Research notes
+The algorithm gives the same results as Oracle and PostGIS but
+    differs from MySQL
+(tried 5.0.21 / 5.0.45 / 5.0.51a / 5.1.23).
+
+Without holes:
+- this:       POINT(4.06923363095238 1.65055803571429)
+- geolib:     POINT(4.07254 1.66819)
+- MySQL:      POINT(3.6636363636364  1.6272727272727)'
+- PostGIS:    POINT(4.06923363095238 1.65055803571429)
+- Oracle:           4.06923363095238 1.65055803571429
+- SQL Server: POINT(4.06923362245959 1.65055804168294)
+
+Statements:
+- \b MySQL/PostGIS: select AsText(Centroid(GeomFromText(
+    'POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2,3.7 1.6,3.4 2,4.1 3,5.3 2.6
+        ,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3))')))
+- \b Oracle: select sdo_geom.sdo_centroid(sdo_geometry(2003, null, null,
+        sdo_elem_info_array(1, 1003, 1), sdo_ordinate_array(
+            2,1.3,2.4,1.7,2.8,1.8,3.4,1.2,3.7,1.6,3.4,2,4.1,3,5.3,2.6
+            ,5.4,1.2,4.9,0.8,2.9,0.7,2,1.3))
+        , mdsys.sdo_dim_array(mdsys.sdo_dim_element('x',0,10,.00000005)
+        ,mdsys.sdo_dim_element('y',0,10,.00000005)))
+        from dual
+- \b SQL Server 2008: select geometry::STGeomFromText(
+    'POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2,3.7 1.6,3.4 2,4.1 3,5.3 2.6
+        ,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3))',0)
+                .STCentroid()
+                .STAsText()
+
+With holes:
+- this:       POINT(4.04663 1.6349)
+- geolib:     POINT(4.04675 1.65735)
+- MySQL:      POINT(3.6090580503834 1.607573932092)
+- PostGIS:    POINT(4.0466265060241 1.63489959839357)
+- Oracle:           4.0466265060241 1.63489959839357
+- SQL Server: POINT(4.0466264962959677 1.6348996057331333)
+
+Statements:
+- \b MySQL/PostGIS: select AsText(Centroid(GeomFromText(
+    'POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2
+        ,3.7 1.6,3.4 2,4.1 3,5.3 2.6,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3)
+        ,(4 2,4.2 1.4,4.8 1.9,4.4 2.2,4 2))')));
+- \b Oracle: select sdo_geom.sdo_centroid(sdo_geometry(2003, null, null
+        , sdo_elem_info_array(1, 1003, 1, 25, 2003, 1)
+        , sdo_ordinate_array(2,1.3,2.4,1.7,2.8,1.8,3.4,1.2,3.7,1.6,3.4,
+        2,4.1,3,5.3,2.6,5.4,1.2,4.9,0.8,2.9,0.7,2,1.3,4,2, 4.2,1.4,
+        4.8,1.9, 4.4,2.2, 4,2))
+        , mdsys.sdo_dim_array(mdsys.sdo_dim_element('x',0,10,.00000005)
+        ,mdsys.sdo_dim_element('y',0,10,.00000005)))
+        from dual
+
+\qbk{
+[heading See also]
+[link geometry.reference.algorithms.centroid.centroid_3_with_strategy centroid (with strategy)]
+}
+
+ */
+template
+<
+    typename Point,
+    typename PointOfSegment = Point,
+    typename CalculationType = void
+>
+class bashein_detmer
+{
+private :
+    // If user specified a calculation type, use that type,
+    //   whatever it is and whatever the point-type(s) are.
+    // Else, use the most appropriate coordinate type
+    //    of the two points, but at least double
+    typedef typename
+        boost::mpl::if_c
+        <
+            boost::is_void<CalculationType>::type::value,
+            typename select_most_precise
+            <
+                typename select_coordinate_type
+                    <
+                        Point,
+                        PointOfSegment
+                    >::type,
+                double
+            >::type,
+            CalculationType
+        >::type calculation_type;
+
+    /*! subclass to keep state */
+    class sums
+    {
+        friend class bashein_detmer;
+        int count;
+        calculation_type sum_a2;
+        calculation_type sum_x;
+        calculation_type sum_y;
+
+    public :
+        inline sums()
+            : count(0)
+            , sum_a2(calculation_type())
+            , sum_x(calculation_type())
+            , sum_y(calculation_type())
+        {
+            typedef calculation_type ct;
+        }
+    };
+
+public :
+    typedef sums state_type;
+
+    static inline void apply(PointOfSegment const& p1,
+            PointOfSegment const& p2, sums& state)
+    {
+        /* Algorithm:
+        For each segment:
+        begin
+            ai = x1 * y2 - x2 * y1;
+            sum_a2 += ai;
+            sum_x += ai * (x1 + x2);
+            sum_y += ai * (y1 + y2);
+        end
+        return POINT(sum_x / (3 * sum_a2), sum_y / (3 * sum_a2) )
+        */
+
+        // Get coordinates and promote them to calculation_type
+        calculation_type const x1 = boost::numeric_cast<calculation_type>(get<0>(p1));
+        calculation_type const y1 = boost::numeric_cast<calculation_type>(get<1>(p1));
+        calculation_type const x2 = boost::numeric_cast<calculation_type>(get<0>(p2));
+        calculation_type const y2 = boost::numeric_cast<calculation_type>(get<1>(p2));
+        calculation_type const ai = x1 * y2 - x2 * y1;
+        state.count++;
+        state.sum_a2 += ai;
+        state.sum_x += ai * (x1 + x2);
+        state.sum_y += ai * (y1 + y2);
+    }
+
+    static inline bool result(sums const& state, Point& centroid)
+    {
+        calculation_type const zero = calculation_type();
+        if (state.count > 0 && state.sum_a2 != zero)
+        {
+            calculation_type const v3 = 3;
+            calculation_type const a3 = v3 * state.sum_a2;
+
+            typedef typename geometry::coordinate_type
+                <
+                    Point
+                >::type coordinate_type;
+
+            set<0>(centroid,
+                boost::numeric_cast<coordinate_type>(state.sum_x / a3));
+            set<1>(centroid,
+                boost::numeric_cast<coordinate_type>(state.sum_y / a3));
+            return true;
+        }
+
+        return false;
+    }
+
+};
+
+#ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
+
+namespace services
+{
+
+// Register this strategy for rings and (multi)polygons, in two dimensions
+template <typename Point, typename Geometry>
+struct default_strategy<cartesian_tag, areal_tag, 2, Point, Geometry>
+{
+    typedef bashein_detmer
+        <
+            Point,
+            typename point_type<Geometry>::type
+        > type;
+};
+
+
+} // namespace services
+
+
+#endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
+
+
+}} // namespace strategy::centroid
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_BASHEIN_DETMER_HPP