349 lines
11 KiB
C++
349 lines
11 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_GEOMETRY_POLICIES_RELATE_DIRECTION_HPP
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#define BOOST_GEOMETRY_GEOMETRY_POLICIES_RELATE_DIRECTION_HPP
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#include <cstddef>
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#include <string>
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#include <boost/concept_check.hpp>
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#include <boost/geometry/strategies/side_info.hpp>
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#include <boost/geometry/util/math.hpp>
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#include <boost/geometry/util/select_calculation_type.hpp>
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#include <boost/geometry/util/select_most_precise.hpp>
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namespace boost { namespace geometry
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{
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namespace policies { namespace relate
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{
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struct direction_type
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{
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inline direction_type(side_info const& s, char h,
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int ha, int hb,
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int da = 0, int db = 0,
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bool op = false)
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: how(h)
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, opposite(op)
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, how_a(ha)
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, how_b(hb)
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, dir_a(da)
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, dir_b(db)
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, sides(s)
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{
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arrival[0] = ha;
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arrival[1] = hb;
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}
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inline direction_type(char h, bool op, int ha = 0, int hb = 0)
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: how(h)
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, opposite(op)
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, how_a(ha)
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, how_b(hb)
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, dir_a(0)
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, dir_b(0)
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{
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arrival[0] = ha;
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arrival[1] = hb;
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}
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// "How" is the intersection formed?
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char how;
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// Is it opposite (for collinear/equal cases)
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bool opposite;
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// Information on how A arrives at intersection, how B arrives at intersection
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// 1: arrives at intersection
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// -1: starts from intersection
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int how_a;
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int how_b;
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// Direction: how is A positioned from B
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// 1: points left, seen from IP
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// -1: points right, seen from IP
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// In case of intersection: B's TO direction
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// In case that B's TO direction is at A: B's from direction
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// In collinear cases: it is 0
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int dir_a; // Direction of A-s TO from IP
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int dir_b; // Direction of B-s TO from IP
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// New information
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side_info sides;
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int arrival[2]; // 1=arrival, -1departure, 0=neutral; == how_a//how_b
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// About arrival[0] (== arrival of a2 w.r.t. b) for COLLINEAR cases
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// Arrival 1: a1--------->a2 (a arrives within b)
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// b1----->b2
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// Arrival 1: (a in b)
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//
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// Arrival -1: a1--------->a2 (a does not arrive within b)
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// b1----->b2
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// Arrival -1: (b in a) a_1-------------a_2
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// b_1---b_2
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// Arrival 0: a1------->a2 (a arrives at TO-border of b)
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// b1--->b2
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};
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template <typename S1, typename S2, typename CalculationType = void>
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struct segments_direction
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{
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typedef direction_type return_type;
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typedef S1 segment_type1;
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typedef S2 segment_type2;
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typedef typename select_calculation_type
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<
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S1, S2, CalculationType
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>::type coordinate_type;
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// Get the same type, but at least a double
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typedef typename select_most_precise<coordinate_type, double>::type rtype;
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static inline return_type segments_intersect(side_info const& sides,
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coordinate_type const& dx1, coordinate_type const& dy1,
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coordinate_type const& dx2, coordinate_type const& dy2,
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S1 const& s1, S2 const& s2)
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{
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bool const ra0 = sides.get<0,0>() == 0;
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bool const ra1 = sides.get<0,1>() == 0;
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bool const rb0 = sides.get<1,0>() == 0;
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bool const rb1 = sides.get<1,1>() == 0;
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return
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// opposite and same starting point (FROM)
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ra0 && rb0 ? calculate_side<1>(sides, dx1, dy1, s1, s2, 'f', -1, -1)
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// opposite and point to each other (TO)
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: ra1 && rb1 ? calculate_side<0>(sides, dx1, dy1, s1, s2, 't', 1, 1)
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// not opposite, forming an angle, first a then b,
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// directed either both left, or both right
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// Check side of B2 from A. This is not calculated before
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: ra1 && rb0 ? angle<1>(sides, dx1, dy1, s1, s2, 'a', 1, -1)
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// not opposite, forming a angle, first b then a,
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// directed either both left, or both right
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: ra0 && rb1 ? angle<0>(sides, dx1, dy1, s1, s2, 'a', -1, 1)
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// b starts from interior of a
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: rb0 ? starts_from_middle(sides, dx1, dy1, s1, s2, 'B', 0, -1)
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// a starts from interior of b (#39)
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: ra0 ? starts_from_middle(sides, dx1, dy1, s1, s2, 'A', -1, 0)
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// b ends at interior of a, calculate direction of A from IP
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: rb1 ? b_ends_at_middle(sides, dx2, dy2, s1, s2)
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// a ends at interior of b
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: ra1 ? a_ends_at_middle(sides, dx1, dy1, s1, s2)
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// normal intersection
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: calculate_side<1>(sides, dx1, dy1, s1, s2, 'i', -1, -1)
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;
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}
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static inline return_type collinear_touch(
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coordinate_type const& ,
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coordinate_type const& , int arrival_a, int arrival_b)
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{
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// Though this is 'collinear', we handle it as To/From/Angle because it is the same.
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// It only does NOT have a direction.
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side_info sides;
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//int const arrive = how == 'T' ? 1 : -1;
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bool opposite = arrival_a == arrival_b;
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return
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! opposite
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? return_type(sides, 'a', arrival_a, arrival_b)
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: return_type(sides, arrival_a == 0 ? 't' : 'f', arrival_a, arrival_b, 0, 0, true);
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}
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template <typename S>
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static inline return_type collinear_interior_boundary_intersect(S const& , bool,
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int arrival_a, int arrival_b, bool opposite)
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{
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return_type r('c', opposite);
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r.arrival[0] = arrival_a;
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r.arrival[1] = arrival_b;
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return r;
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}
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static inline return_type collinear_a_in_b(S1 const& , bool opposite)
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{
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return_type r('c', opposite);
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r.arrival[0] = 1;
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r.arrival[1] = -1;
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return r;
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}
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static inline return_type collinear_b_in_a(S2 const& , bool opposite)
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{
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return_type r('c', opposite);
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r.arrival[0] = -1;
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r.arrival[1] = 1;
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return r;
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}
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static inline return_type collinear_overlaps(
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coordinate_type const& , coordinate_type const& ,
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coordinate_type const& , coordinate_type const& ,
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int arrival_a, int arrival_b, bool opposite)
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{
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return_type r('c', opposite);
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r.arrival[0] = arrival_a;
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r.arrival[1] = arrival_b;
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return r;
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}
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static inline return_type segment_equal(S1 const& , bool opposite)
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{
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return return_type('e', opposite);
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}
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static inline return_type degenerate(S1 const& , bool)
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{
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return return_type('0', false);
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}
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static inline return_type disjoint()
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{
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return return_type('d', false);
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}
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static inline return_type collinear_disjoint()
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{
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return return_type('d', false);
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}
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static inline return_type parallel()
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{
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return return_type('p', false);
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}
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static inline return_type error(std::string const& msg)
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{
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// msg
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return return_type('d', false);
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}
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private :
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template <std::size_t I>
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static inline return_type calculate_side(side_info const& sides,
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coordinate_type const& dx1, coordinate_type const& dy1,
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S1 const& s1, S2 const& s2,
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char how, int how_a, int how_b)
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{
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coordinate_type dpx = get<I, 0>(s2) - get<0, 0>(s1);
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coordinate_type dpy = get<I, 1>(s2) - get<0, 1>(s1);
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// This is a "side calculation" as in the strategies, but here two terms are precalculated
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// We might merge this with side, offering a pre-calculated term
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// Waiting for implementing spherical...
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return dx1 * dpy - dy1 * dpx > 0
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? return_type(sides, how, how_a, how_b, -1, 1)
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: return_type(sides, how, how_a, how_b, 1, -1);
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}
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template <std::size_t I>
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static inline return_type angle(side_info const& sides,
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coordinate_type const& dx1, coordinate_type const& dy1,
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S1 const& s1, S2 const& s2,
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char how, int how_a, int how_b)
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{
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coordinate_type dpx = get<I, 0>(s2) - get<0, 0>(s1);
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coordinate_type dpy = get<I, 1>(s2) - get<0, 1>(s1);
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return dx1 * dpy - dy1 * dpx > 0
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? return_type(sides, how, how_a, how_b, 1, 1)
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: return_type(sides, how, how_a, how_b, -1, -1);
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}
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static inline return_type starts_from_middle(side_info const& sides,
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coordinate_type const& dx1, coordinate_type const& dy1,
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S1 const& s1, S2 const& s2,
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char which,
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int how_a, int how_b)
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{
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// Calculate ARROW of b segment w.r.t. s1
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coordinate_type dpx = get<1, 0>(s2) - get<0, 0>(s1);
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coordinate_type dpy = get<1, 1>(s2) - get<0, 1>(s1);
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int dir = dx1 * dpy - dy1 * dpx > 0 ? 1 : -1;
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// From other perspective, then reverse
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bool const is_a = which == 'A';
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if (is_a)
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{
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dir = -dir;
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}
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return return_type(sides, 's',
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how_a,
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how_b,
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is_a ? dir : -dir,
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! is_a ? dir : -dir);
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}
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// To be harmonized
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static inline return_type a_ends_at_middle(side_info const& sides,
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coordinate_type const& dx, coordinate_type const& dy,
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S1 const& s1, S2 const& s2)
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{
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coordinate_type dpx = get<1, 0>(s2) - get<0, 0>(s1);
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coordinate_type dpy = get<1, 1>(s2) - get<0, 1>(s1);
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// Ending at the middle, one ARRIVES, the other one is NEUTRAL
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// (because it both "arrives" and "departs" there
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return dx * dpy - dy * dpx > 0
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? return_type(sides, 'm', 1, 0, 1, 1)
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: return_type(sides, 'm', 1, 0, -1, -1);
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}
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static inline return_type b_ends_at_middle(side_info const& sides,
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coordinate_type const& dx, coordinate_type const& dy,
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S1 const& s1, S2 const& s2)
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{
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coordinate_type dpx = get<1, 0>(s1) - get<0, 0>(s2);
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coordinate_type dpy = get<1, 1>(s1) - get<0, 1>(s2);
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return dx * dpy - dy * dpx > 0
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? return_type(sides, 'm', 0, 1, 1, 1)
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: return_type(sides, 'm', 0, 1, -1, -1);
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}
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};
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}} // namespace policies::relate
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_GEOMETRY_POLICIES_RELATE_DIRECTION_HPP
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