[Boost-commit] svn:boost r84131 - trunk/boost/geometry/index/detail/algorithms

Subject: [Boost-commit] svn:boost r84131 - trunk/boost/geometry/index/detail/algorithms
From: adam.wulkiewicz_at_[hidden]
Date: 2013-05-03 22:08:21

Author: awulkiew
Date: 2013-05-03 22:08:21 EDT (Fri, 03 May 2013)
New Revision: 84131
URL: http://svn.boost.org/trac/boost/changeset/84131

Log:
geometry.index: added path_intersection algorithm.
Added:
   trunk/boost/geometry/index/detail/algorithms/path_intersection.hpp   (contents, props changed)

Added: trunk/boost/geometry/index/detail/algorithms/path_intersection.hpp
==============================================================================
--- (empty file)
+++ trunk/boost/geometry/index/detail/algorithms/path_intersection.hpp	2013-05-03 22:08:21 EDT (Fri, 03 May 2013)
@@ -0,0 +1,90 @@
+// Boost.Geometry Index
+//
+// n-dimensional box-linestring intersection
+//
+// Copyright (c) 2011-2013 Adam Wulkiewicz, Lodz, Poland.
+//
+// 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_INDEX_DETAIL_ALGORITHMS_PATH_INTERSECTION_HPP
+#define BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_PATH_INTERSECTION_HPP
+
+#include <boost/geometry/index/detail/algorithms/segment_intersection.hpp>
+
+namespace boost { namespace geometry { namespace index { namespace detail {
+
+namespace dispatch {
+
+template <typename Indexable, typename LineString, typename Tag>
+struct path_intersection
+{
+    BOOST_MPL_ASSERT_MSG((false), NOT_IMPLEMENTED_FOR_THIS_GEOMETRY, (path_intersection));
+};
+
+template <typename Indexable, typename Linestring>
+struct path_intersection<Indexable, Linestring, point_tag>
+{
+    BOOST_MPL_ASSERT_MSG((false), SEGMENT_POINT_INTERSECTION_UNAVAILABLE, (path_intersection));
+};
+
+template <typename Indexable, typename Linestring>
+struct path_intersection<Indexable, Linestring, box_tag>
+{
+    typedef typename default_length_result<Linestring>::type length_type;
+
+    static inline bool apply(Indexable const& b, Linestring const& path, length_type & distance)
+    {
+        typedef typename ::boost::range_value<Linestring>::type point_type;
+        typedef typename default_relative_distance_type<Indexable, point_type>::type relative_distance_type;
+        typedef typename ::boost::range_const_iterator<Linestring>::type const_iterator;        
+
+        if ( ::boost::size(path) < 2 )
+            return false;
+
+        const_iterator it0 = ::boost::begin(path);
+        const_iterator it1 = ::boost::begin(path) + 1;
+        const_iterator last = ::boost::end(path);
+
+        distance = 0;
+
+        for ( ; it1 != last ; ++it0, ++it1 )
+        {
+            typename default_distance_result<point_type, point_type>::type
+                dist = geometry::distance(*it0, *it1);
+
+            relative_distance_type rel_dist;
+            if ( index::detail::segment_intersection(b, *it0, *it1, rel_dist) )
+            {
+                distance += dist * rel_dist;
+                return true;
+            }
+            else
+                distance += dist;
+        }
+
+        return false;
+    }
+};
+
+} // namespace dispatch
+
+// TODO - change the name e.g. to path_intersection_distance
+//        and segment_intersection e.g. to segment_intersection_relative_distance
+
+template <typename Indexable, typename Linestring> inline
+bool path_intersection(Indexable const& b,
+                       Linestring const& path,
+                       typename default_length_result<Linestring>::type & distance)
+{
+    // TODO check Indexable and Linestring concepts
+
+    return dispatch::path_intersection<
+            Indexable, Linestring, typename detail::traits::tag<Indexable>::type
+        >::apply(b, path, distance);
+}
+
+}}}} // namespace boost::geometry::index::detail
+
+#endif // BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_PATH_INTERSECTION_HPP