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https://github.com/boostorg/geometry.git
synced 2026-02-09 11:12:21 +00:00
[algorithms][is_simple] optimize the computation of turns for
multilinestrings: instead of computing the turns for each linestring (through bg::intersects) and then again for the entire multilinestring, avoid computing the turns for the individual linestrings in the multilinestring and compute and process all multilinestring turns together; besides the optimization this approach fixes a bug in bg::intersects in the context of simplicity testing: bg::intersects cannot detect the intersection occuring when a boundary point of linestring is also an internal point of the linestring, as in LINESTRING(4 1,10 8,4 6,4 1,10 5,10 3), for example;
This commit is contained in:
Menelaos Karavelas
@@ -1,6 +1,6 @@
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// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2014, Oracle and/or its affiliates.
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// Copyright (c) 2014-2015, Oracle and/or its affiliates.
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// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
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@@ -19,6 +19,7 @@
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#include <boost/geometry/core/closure.hpp>
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#include <boost/geometry/core/coordinate_type.hpp>
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#include <boost/geometry/core/point_type.hpp>
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#include <boost/geometry/core/tag.hpp>
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#include <boost/geometry/core/tags.hpp>
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#include <boost/geometry/util/range.hpp>
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@@ -29,8 +30,10 @@
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#include <boost/geometry/algorithms/equals.hpp>
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#include <boost/geometry/algorithms/intersects.hpp>
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#include <boost/geometry/algorithms/not_implemented.hpp>
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#include <boost/geometry/algorithms/detail/check_iterator_range.hpp>
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#include <boost/geometry/algorithms/detail/signed_index_type.hpp>
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#include <boost/geometry/algorithms/detail/disjoint/linear_linear.hpp>
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#include <boost/geometry/algorithms/detail/overlay/get_turn_info.hpp>
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@@ -54,128 +57,210 @@ namespace detail { namespace is_simple
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{
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template <typename Turn>
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inline bool check_segment_indices(Turn const& turn,
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signed_index_type last_index)
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{
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return
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(turn.operations[0].seg_id.segment_index == 0
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&& turn.operations[1].seg_id.segment_index == last_index)
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||
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(turn.operations[0].seg_id.segment_index == 0
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&& turn.operations[1].seg_id.segment_index == last_index);
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}
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template <typename Geometry, typename Tag = typename tag<Geometry>::type>
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class is_acceptable_turn
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: not_implemented<Geometry>
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{};
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template <typename Linestring>
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class is_acceptable_turn<Linestring, linestring_tag>
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{
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public:
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is_acceptable_turn(Linestring const& linestring)
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: m_linestring(linestring)
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, m_is_closed(geometry::equals(range::front(linestring),
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range::back(linestring)))
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{}
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template <typename Turn>
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inline bool apply(Turn const& turn) const
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{
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BOOST_ASSERT(boost::size(m_linestring) > 1);
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return m_is_closed
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&& turn.method == overlay::method_none
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&& check_segment_indices(turn, boost::size(m_linestring) - 2)
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&& geometry::equals(range::front(m_linestring), turn.point);
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}
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private:
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Linestring const& m_linestring;
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bool const m_is_closed;
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};
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template <typename MultiLinestring>
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class is_acceptable_turn<MultiLinestring, multi_linestring_tag>
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{
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private:
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typedef typename boost::range_value<MultiLinestring>::type linestring_type;
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typedef is_acceptable_turn<linestring_type> base_type;
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template <typename Point, typename Linestring>
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static inline bool is_boundary_point_of(Point const& point,
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Linestring const& linestring)
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{
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BOOST_ASSERT(boost::size(linestring) > 1);
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return
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! geometry::equals(range::front(linestring),
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range::back(linestring))
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&&
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(geometry::equals(point, range::front(linestring))
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|| geometry::equals(point, range::back(linestring)));
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}
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template <typename Turn, typename Linestring>
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static inline bool is_closing_point_of(Turn const& turn,
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Linestring const& linestring)
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{
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BOOST_ASSERT(boost::size(linestring) > 1);
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return
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turn.method == overlay::method_none
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&&
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check_segment_indices(turn, boost::size(linestring) - 2)
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&&
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geometry::equals(range::front(linestring), range::back(linestring))
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&&
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geometry::equals(range::front(linestring), turn.point)
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;
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}
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template <typename Linestring1, typename Linestring2>
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static inline bool have_same_boundary_points(Linestring1 const& ls1,
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Linestring2 const& ls2)
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{
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return
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geometry::equals(range::front(ls1), range::front(ls2))
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?
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geometry::equals(range::back(ls1), range::back(ls2))
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:
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(geometry::equals(range::front(ls1), range::back(ls2))
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&&
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geometry::equals(range::back(ls1), range::front(ls2)))
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;
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}
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public:
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is_acceptable_turn(MultiLinestring const& multilinestring)
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: m_multilinestring(multilinestring)
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{}
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template <typename Turn>
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inline bool apply(Turn const& turn) const
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{
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linestring_type const& ls1 =
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range::at(m_multilinestring, turn.operations[0].seg_id.multi_index);
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linestring_type const& ls2 =
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range::at(m_multilinestring, turn.operations[1].seg_id.multi_index);
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if (turn.operations[0].seg_id.multi_index
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== turn.operations[1].seg_id.multi_index)
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{
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return is_closing_point_of(turn, ls1);
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}
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return
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is_boundary_point_of(turn.point, ls1)
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&& is_boundary_point_of(turn.point, ls2)
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&&
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( boost::size(ls1) != 2
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|| boost::size(ls2) != 2
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|| ! have_same_boundary_points(ls1, ls2) );
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}
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private:
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MultiLinestring const& m_multilinestring;
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};
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template <typename Linear>
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inline bool has_self_intersections(Linear const& linear)
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{
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typedef typename point_type<Linear>::type point_type;
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// compute self turns
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typedef detail::overlay::turn_info
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<
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point_type,
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geometry::segment_ratio
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<
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typename geometry::coordinate_type<point_type>::type
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>
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> turn_info;
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std::deque<turn_info> turns;
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typedef detail::overlay::get_turn_info
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<
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detail::disjoint::assign_disjoint_policy
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> turn_policy;
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is_acceptable_turn<Linear> predicate(linear);
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detail::overlay::predicate_based_interrupt_policy
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<
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is_acceptable_turn<Linear>
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> interrupt_policy(predicate);
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detail::self_get_turn_points::get_turns
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<
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turn_policy
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>::apply(linear,
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detail::no_rescale_policy(),
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turns,
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interrupt_policy);
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detail::is_valid::debug_print_turns(turns.begin(), turns.end());
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debug_print_boundary_points(linear);
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return interrupt_policy.has_intersections;
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}
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template <typename Linestring, bool CheckSelfIntersections = true>
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struct is_simple_linestring
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{
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static inline bool apply(Linestring const& linestring)
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{
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return !detail::is_valid::has_duplicates
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return ! detail::is_valid::has_duplicates
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<
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Linestring, closed
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>::apply(linestring)
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&& !detail::is_valid::has_spikes
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&& ! detail::is_valid::has_spikes
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<
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Linestring, closed
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>::apply(linestring)
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&& !(CheckSelfIntersections && geometry::intersects(linestring));
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&& ! (CheckSelfIntersections && has_self_intersections(linestring));
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}
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};
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template <typename MultiLinestring>
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class is_simple_multilinestring
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struct is_simple_multilinestring
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{
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private:
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class is_acceptable_turn
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{
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private:
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template <typename Point, typename Linestring>
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static inline bool is_boundary_point_of(Point const& point,
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Linestring const& linestring)
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{
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BOOST_ASSERT( boost::size(linestring) > 1 );
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return
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!geometry::equals(range::front(linestring),
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range::back(linestring))
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&&
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( geometry::equals(point, range::front(linestring))
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|| geometry::equals(point, range::back(linestring)) );
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}
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template <typename Point, typename Linestring>
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static inline bool is_closing_point_of(Point const& point,
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Linestring const& linestring)
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{
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BOOST_ASSERT( boost::size(linestring) > 1 );
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return
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geometry::equals(range::front(linestring),
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range::back(linestring))
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&&
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geometry::equals(range::front(linestring), point)
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;
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}
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template <typename Linestring1, typename Linestring2>
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static inline bool have_same_boundary_points(Linestring1 const& ls1,
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Linestring2 const& ls2)
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{
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return
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geometry::equals(range::front(ls1), range::front(ls2))
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?
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geometry::equals(range::back(ls1), range::back(ls2))
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:
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(geometry::equals(range::front(ls1), range::back(ls2))
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&&
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geometry::equals(range::back(ls1), range::front(ls2))
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)
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;
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}
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public:
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is_acceptable_turn(MultiLinestring const& multilinestring)
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: m_multilinestring(multilinestring)
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{}
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template <typename Turn>
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inline bool apply(Turn const& turn) const
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{
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typedef typename boost::range_value
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<
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MultiLinestring
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>::type linestring;
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linestring const& ls1 =
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range::at(m_multilinestring,
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turn.operations[0].seg_id.multi_index);
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linestring const& ls2 =
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range::at(m_multilinestring,
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turn.operations[1].seg_id.multi_index);
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if (turn.operations[0].seg_id.multi_index
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== turn.operations[1].seg_id.multi_index)
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{
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BOOST_ASSERT(is_closing_point_of(turn.point, ls1));
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return true;
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}
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return
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is_boundary_point_of(turn.point, ls1)
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&& is_boundary_point_of(turn.point, ls2)
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&&
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( boost::size(ls1) != 2
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|| boost::size(ls2) != 2
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|| !have_same_boundary_points(ls1, ls2) );
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}
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private:
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MultiLinestring const& m_multilinestring;
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};
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public:
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static inline bool apply(MultiLinestring const& multilinestring)
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{
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typedef typename boost::range_value<MultiLinestring>::type linestring;
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typedef typename point_type<MultiLinestring>::type point_type;
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typedef point_type point;
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// check each of the linestrings for simplicity
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if ( !detail::check_iterator_range
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// but do not compute self-intersections yet; these will be
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// computed for the entire multilinestring
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if ( ! detail::check_iterator_range
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<
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is_simple_linestring<linestring>,
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is_simple_linestring
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<
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typename boost::range_value<MultiLinestring>::type,
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false // do not compute self-intersections
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>,
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false // do not allow empty multilinestring
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>::apply(boost::begin(multilinestring),
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boost::end(multilinestring))
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@@ -184,44 +269,8 @@ public:
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return false;
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}
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// compute self turns
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typedef detail::overlay::turn_info
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<
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point_type,
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geometry::segment_ratio
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<
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typename geometry::coordinate_type<point>::type
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>
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> turn_info;
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std::deque<turn_info> turns;
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typedef detail::overlay::get_turn_info
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<
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detail::disjoint::assign_disjoint_policy
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> turn_policy;
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is_acceptable_turn predicate(multilinestring);
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detail::overlay::predicate_based_interrupt_policy
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<
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is_acceptable_turn
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> interrupt_policy(predicate);
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detail::self_get_turn_points::get_turns
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<
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turn_policy
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>::apply(multilinestring,
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detail::no_rescale_policy(),
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turns,
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interrupt_policy);
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detail::is_valid::debug_print_turns(turns.begin(), turns.end());
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debug_print_boundary_points(multilinestring);
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return !interrupt_policy.has_intersections;
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return ! has_self_intersections(multilinestring);
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}
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};
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