// Boost.Geometry
// Copyright (c) 2007-2023 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2017-2023 Adam Wulkiewicz, Lodz, Poland.
// This file was modified by Oracle on 2015-2022.
// Modifications copyright (c) 2015-2022 Oracle and/or its affiliates.
// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
// 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_ALGORITHMS_DETAIL_OVERLAY_GET_TURN_INFO_HPP
#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_TURN_INFO_HPP
#include <boost/core/ignore_unused.hpp>
#include <boost/throw_exception.hpp>
#include <boost/geometry/core/access.hpp>
#include <boost/geometry/core/assert.hpp>
#include <boost/geometry/core/config.hpp>
#include <boost/geometry/core/exception.hpp>
#include <boost/geometry/algorithms/convert.hpp>
#include <boost/geometry/algorithms/detail/overlay/get_distance_measure.hpp>
#include <boost/geometry/algorithms/detail/overlay/turn_info.hpp>
#include <boost/geometry/algorithms/detail/overlay/get_turn_info_helpers.hpp>
#include <boost/geometry/util/constexpr.hpp>
namespace boost { namespace geometry
{
#if ! defined(BOOST_GEOMETRY_OVERLAY_NO_THROW)
class turn_info_exception : public geometry::exception
{
std::string message;
public:
// NOTE: "char" will be replaced by enum in future version
inline turn_info_exception(char const method)
{
message = "Boost.Geometry Turn exception: ";
message += method;
}
virtual char const* What() const noexcept
{
return message.c_str();
}
};
#endif
#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace overlay
{
struct policy_verify_nothing
{
static bool const use_side_verification = false;
static bool const use_start_turn = false;
static bool const use_handle_as_touch = false;
static bool const use_handle_as_equal = false;
static bool const use_handle_imperfect_touch = false;
};
struct policy_verify_all
{
static bool const use_side_verification = true;
static bool const use_start_turn = true;
static bool const use_handle_as_touch = true;
static bool const use_handle_as_equal = true;
static bool const use_handle_imperfect_touch = true;
};
#if defined(BOOST_GEOMETRY_USE_RESCALING)
using verify_policy_aa = policy_verify_nothing;
#else
using verify_policy_aa = policy_verify_all;
#endif
using verify_policy_ll = policy_verify_nothing;
using verify_policy_la = policy_verify_nothing;
struct base_turn_handler
{
// Returns true if both sides are opposite
static inline bool opposite(int side1, int side2)
{
// We cannot state side1 == -side2, because 0 == -0
// So either side1*side2==-1 or side1==-side2 && side1 != 0
return side1 * side2 == -1;
}
// Same side of a segment (not being 0)
static inline bool same(int side1, int side2)
{
return side1 * side2 == 1;
}
// Both get the same operation
template <typename TurnInfo>
static inline void both(TurnInfo& ti, operation_type const op)
{
ti.operations[0].operation = op;
ti.operations[1].operation = op;
}
// If condition, first union/second intersection, else vice versa
template <typename TurnInfo>
static inline void ui_else_iu(bool condition, TurnInfo& ti)
{
ti.operations[0].operation = condition
? operation_union : operation_intersection;
ti.operations[1].operation = condition
? operation_intersection : operation_union;
}
// If condition, both union, else both intersection
template <typename TurnInfo>
static inline void uu_else_ii(bool condition, TurnInfo& ti)
{
both(ti, condition ? operation_union : operation_intersection);
}
template <typename TurnInfo, typename IntersectionInfo>
static inline void assign_point(TurnInfo& ti,
method_type method,
IntersectionInfo const& info, unsigned int index)
{
ti.method = method;
BOOST_GEOMETRY_ASSERT(index < info.count);
geometry::convert(info.intersections[index], ti.point);
ti.operations[0].fraction = info.fractions[index].robust_ra;
ti.operations[1].fraction = info.fractions[index].robust_rb;
}
template <typename TurnInfo, typename IntersectionInfo, typename DirInfo>
static inline void assign_point_and_correct(TurnInfo& ti,
method_type method,
IntersectionInfo const& info, DirInfo const& dir_info)
{
ti.method = method;
// For touch/touch interior always take the intersection point 0
// (usually there is only one - but if collinear is handled as touch, both could be taken).
static int const index = 0;
geometry::convert(info.intersections[index], ti.point);
for (int i = 0; i < 2; i++)
{
if (dir_info.arrival[i] == 1)
{
// The segment arrives at the intersection point, its fraction should be 1
// (due to precision it might be nearly so, but not completely, in rare cases)
ti.operations[i].fraction = {1, 1};
}
else if (dir_info.arrival[i] == -1)
{
// The segment leaves from the intersection point, likewise its fraction should be 0
ti.operations[i].fraction = {0, 1};
}
else
{
ti.operations[i].fraction = i == 0 ? info.fractions[index].robust_ra
: info.fractions[index].robust_rb;
}
}
}
template <typename IntersectionInfo>
static inline unsigned int non_opposite_to_index(IntersectionInfo const& info)
{
return info.fractions[0].robust_rb < info.fractions[1].robust_rb
? 1 : 0;
}
};
template<typename VerifyPolicy>
struct turn_info_verification_functions
{
template <typename Point1, typename Point2>
static inline
typename select_coordinate_type<Point1, Point2>::type
distance_measure(Point1 const& a, Point2 const& b)
{
// TODO: revise this using comparable distance for various
// coordinate systems
using coor_t = typename select_coordinate_type<Point1, Point2>::type;
coor_t const dx = get<0>(a) - get<0>(b);
coor_t const dy = get<1>(a) - get<1>(b);
return dx * dx + dy * dy;
}
template
<
std::size_t IndexP,
std::size_t IndexQ,
typename UniqueSubRange1,
typename UniqueSubRange2,
typename UmbrellaStrategy,
typename TurnInfo
>
static inline void set_both_verified(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
UmbrellaStrategy const& umbrella_strategy,
std::size_t index_p, std::size_t index_q,
TurnInfo& ti)
{
BOOST_GEOMETRY_ASSERT(IndexP + IndexQ == 1);
BOOST_GEOMETRY_ASSERT(index_p > 0 && index_p <= 2);
BOOST_GEOMETRY_ASSERT(index_q > 0 && index_q <= 2);
using distance_measure_result_type = typename geometry::coordinate_type<decltype(ti.point)>::type;
bool const p_in_range = index_p < range_p.size();
bool const q_in_range = index_q < range_q.size();
ti.operations[IndexP].remaining_distance
= p_in_range
? distance_measure(ti.point, range_p.at(index_p))
: distance_measure_result_type{0};
ti.operations[IndexQ].remaining_distance
= q_in_range
? distance_measure(ti.point, range_q.at(index_q))
: distance_measure_result_type{0};
if (p_in_range && q_in_range)
{
// pk/q2 is considered as collinear, but there might be
// a tiny measurable difference. If so, use that.
// Calculate pk // qj-qk
bool const p_closer
= ti.operations[IndexP].remaining_distance
< ti.operations[IndexQ].remaining_distance;
auto const dm
= p_closer
? get_distance_measure(range_q.at(index_q - 1),
range_q.at(index_q), range_p.at(index_p),
umbrella_strategy)
: get_distance_measure(range_p.at(index_p - 1),
range_p.at(index_p), range_q.at(index_q),
umbrella_strategy);
if (! dm.is_zero())
{
// Not truely collinear, distinguish for union/intersection
// If p goes left (positive), take that for a union
bool const p_left
= p_closer ? dm.is_positive() : dm.is_negative();
ti.operations[IndexP].operation = p_left
? operation_union : operation_intersection;
ti.operations[IndexQ].operation = p_left
? operation_intersection : operation_union;
return;
}
}
base_turn_handler::both(ti, operation_continue);
}
template
<
std::size_t IndexP,
std::size_t IndexQ,
typename UniqueSubRange1,
typename UniqueSubRange2,
typename UmbrellaStrategy,
typename TurnInfo
>
static inline void both_collinear(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
UmbrellaStrategy const& umbrella_strategy,
std::size_t index_p, std::size_t index_q,
TurnInfo& ti)
{
if BOOST_GEOMETRY_CONSTEXPR (VerifyPolicy::use_side_verification)
{
set_both_verified<IndexP, IndexQ>(range_p, range_q, umbrella_strategy,
index_p, index_q, ti);
}
else
{
base_turn_handler::both(ti, operation_continue);
}
}
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename UmbrellaStrategy
>
static inline int verified_side(int side,
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
UmbrellaStrategy const& umbrella_strategy,
int index_p, int index_q)
{
if BOOST_GEOMETRY_CONSTEXPR (VerifyPolicy::use_side_verification)
{
if (side == 0)
{
if (index_p >= 1 && range_p.is_last_segment())
{
return 0;
}
if (index_q >= 2 && range_q.is_last_segment())
{
return 0;
}
auto const dm = get_distance_measure(range_p.at(index_p),
range_p.at(index_p + 1),
range_q.at(index_q),
umbrella_strategy);
static decltype(dm.measure) const zero = 0;
return dm.measure == zero ? 0 : dm.measure > zero ? 1 : -1;
}
}
return side;
}
};
template
<
typename TurnInfo,
typename VerifyPolicy
>
struct touch_interior : public base_turn_handler
{
using fun = turn_info_verification_functions<VerifyPolicy>;
template
<
typename IntersectionInfo,
typename UniqueSubRange
>
static bool handle_as_touch(IntersectionInfo const& info,
UniqueSubRange const& non_touching_range)
{
if BOOST_GEOMETRY_CONSTEXPR (! VerifyPolicy::use_handle_as_touch)
{
return false;
}
else // else prevents unreachable code warning
{
//
//
// ^ Q(i) ^ P(i)
// \ /
// \ /
// \ /
// \ /
// \ /
// \ /
// \ /
// \ /
// \ /
// \ / it is about buffer_rt_r
// P(k) v/ they touch here "in the middle", but at the intersection...
// <---------------->v there is no follow up IP
// /
// /
// /
// /
// /
// /
// v Q(k)
//
// Measure where the IP is located. If it is really close to the end,
// then there is no space for the next IP (on P(1)/Q(2). A "from"
// intersection will be generated, but those are never handled.
// Therefore handle it as a normal touch (two segments arrive at the
// intersection point). It currently checks for zero, but even a
// distance a little bit larger would do.
auto const dm = fun::distance_measure(info.intersections[0], non_touching_range.at(1));
decltype(dm) const zero = 0;
bool const result = math::equals(dm, zero);
return result;
}
}
// Index: 0, P is the interior, Q is touching and vice versa
template
<
unsigned int Index,
typename UniqueSubRange1,
typename UniqueSubRange2,
typename IntersectionInfo,
typename DirInfo,
typename SidePolicy,
typename UmbrellaStrategy
>
static inline void apply(UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
TurnInfo& ti,
IntersectionInfo const& intersection_info,
DirInfo const& dir_info,
SidePolicy const& side,
UmbrellaStrategy const& umbrella_strategy)
{
assign_point_and_correct(ti, method_touch_interior, intersection_info, dir_info);
// Both segments of q touch segment p somewhere in its interior
// 1) We know: if q comes from LEFT or RIGHT
// (i.e. dir_info.sides.get<Index,0>() == 1 or -1)
// 2) Important is: if q_k goes to LEFT, RIGHT, COLLINEAR
// and, if LEFT/COLL, if it is lying LEFT or RIGHT w.r.t. q_i
BOOST_STATIC_ASSERT(Index <= 1);
static unsigned int const index_p = Index;
static unsigned int const index_q = 1 - Index;
bool const has_pk = ! range_p.is_last_segment();
bool const has_qk = ! range_q.is_last_segment();
int const side_qi_p = dir_info.sides.template get<index_q, 0>();
int const side_qk_p = has_qk ? side.qk_wrt_p1() : 0;
if (side_qi_p == -side_qk_p)
{
// Q crosses P from left->right or from right->left (test "ML1")
// Union: folow P (left->right) or Q (right->left)
// Intersection: other turn
unsigned int index = side_qk_p == -1 ? index_p : index_q;
ti.operations[index].operation = operation_union;
ti.operations[1 - index].operation = operation_intersection;
return;
}
int const side_qk_q = has_qk ? side.qk_wrt_q1() : 0;
// Only necessary if rescaling is turned off:
int const side_pj_q2 = has_qk ? side.pj_wrt_q2() : 0;
if (side_qi_p == -1 && side_qk_p == -1 && side_qk_q == 1)
{
// Q turns left on the right side of P (test "MR3")
// Both directions for "intersection"
both(ti, operation_intersection);
ti.touch_only = true;
}
else if (side_qi_p == 1 && side_qk_p == 1 && side_qk_q == -1)
{
if (has_qk && side_pj_q2 == -1)
{
// Q turns right on the left side of P (test "ML3")
// Union: take both operations
// Intersection: skip
both(ti, operation_union);
}
else
{
// q2 is collinear with p1, so it does not turn back. This
// can happen in floating point precision. In this case,
// block one of the operations to avoid taking that path.
ti.operations[index_p].operation = operation_union;
ti.operations[index_q].operation = operation_blocked;
}
ti.touch_only = true;
}
else if (side_qi_p == side_qk_p && side_qi_p == side_qk_q)
{
// Q turns left on the left side of P (test "ML2")
// or Q turns right on the right side of P (test "MR2")
// Union: take left turn (Q if Q turns left, P if Q turns right)
// Intersection: other turn
unsigned int index = side_qk_q == 1 ? index_q : index_p;
if (has_qk && side_pj_q2 == 0)
{
// Even though sides xk w.r.t. 1 are distinct, pj is collinear
// with q. Therefore swap the path
index = 1 - index;
}
if (has_pk && has_qk && opposite(side_pj_q2, side_qi_p))
{
// Without rescaling, floating point requires extra measures
int const side_qj_p1 = side.qj_wrt_p1();
int const side_qj_p2 = side.qj_wrt_p2();
if (same(side_qj_p1, side_qj_p2))
{
int const side_pj_q1 = side.pj_wrt_q1();
if (opposite(side_pj_q1, side_pj_q2))
{
index = 1 - index;
}
}
}
ti.operations[index].operation = operation_union;
ti.operations[1 - index].operation = operation_intersection;
ti.touch_only = true;
}
else if (side_qk_p == 0)
{
// Q intersects on interior of P and continues collinearly
if (side_qk_q == side_qi_p)
{
fun::template both_collinear<index_p, index_q>(range_p, range_q, umbrella_strategy,
1, 2, ti);
}
else
{
// Opposite direction, which is never travelled.
// If Q turns left, P continues for intersection
// If Q turns right, P continues for union
ti.operations[index_p].operation = side_qk_q == 1
? operation_intersection
: operation_union;
ti.operations[index_q].operation = operation_blocked;
}
}
else
{
// Should not occur!
ti.method = method_error;
}
}
};
template
<
typename TurnInfo,
typename VerifyPolicy
>
struct touch : public base_turn_handler
{
using fun = turn_info_verification_functions<VerifyPolicy>;
static inline bool between(int side1, int side2, int turn)
{
return side1 == side2 && ! opposite(side1, turn);
}
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename UmbrellaStrategy
>
static inline bool handle_imperfect_touch(UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
int side_pk_q2,
UmbrellaStrategy const& umbrella_strategy,
TurnInfo& ti)
{
if BOOST_GEOMETRY_CONSTEXPR (! VerifyPolicy::use_handle_imperfect_touch)
{
return false;
}
else // else prevents unreachable code warning
{
// Q
// ^
// ||
// ||
// |^----
// >----->P
// * * they touch here (P/Q are (nearly) on top)
//
// Q continues from where P comes.
// P continues from where Q comes
// This is often a blocking situation,
// unless there are FP issues: there might be a distance
// between Pj and Qj, in that case handle it as a union.
//
// Exaggerated:
// Q
// ^ Q is nearly vertical
// \ but not completely - and still ends above P
// | \qj In this case it should block P and
// | ^------ set Q to Union
// >----->P qj is LEFT of P1 and pi is LEFT of Q2
// (the other way round is also possible)
auto has_distance = [&](auto const& r1, auto const& r2) -> bool
{
auto const d1 = get_distance_measure(r1.at(0), r1.at(1), r2.at(1), umbrella_strategy);
auto const d2 = get_distance_measure(r2.at(1), r2.at(2), r1.at(0), umbrella_strategy);
return d1.measure > 0 && d2.measure > 0;
};
if (side_pk_q2 == -1 && has_distance(range_p, range_q))
{
// Even though there is a touch, Q(j) is left of P1
// and P(i) is still left from Q2.
// Q continues to the right.
// It can continue.
ti.operations[0].operation = operation_blocked;
// Q turns right -> union (both independent),
// Q turns left -> intersection
ti.operations[1].operation = operation_union;
ti.touch_only = true;
return true;
}
if (side_pk_q2 == 1 && has_distance(range_q, range_p))
{
// Similarly, but the other way round.
// Q continues to the left.
ti.operations[0].operation = operation_union;
ti.operations[1].operation = operation_blocked;
ti.touch_only = true;
return true;
}
return false;
}
}
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename IntersectionInfo,
typename DirInfo,
typename SideCalculator,
typename UmbrellaStrategy
>
static inline void apply(UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
TurnInfo& ti,
IntersectionInfo const& intersection_info,
DirInfo const& dir_info,
SideCalculator const& side,
UmbrellaStrategy const& umbrella_strategy)
{
assign_point_and_correct(ti, method_touch, intersection_info, dir_info);
bool const has_pk = ! range_p.is_last_segment();
bool const has_qk = ! range_q.is_last_segment();
int const side_pk_q1 = has_pk ? side.pk_wrt_q1() : 0;
int const side_qi_p1 = fun::verified_side(dir_info.sides.template get<1, 0>(),
range_p, range_q, umbrella_strategy, 0, 0);
int const side_qk_p1 = has_qk
? fun::verified_side(side.qk_wrt_p1(), range_p, range_q,
umbrella_strategy, 0, 2)
: 0;
// If Qi and Qk are both at same side of Pi-Pj,
// or collinear (so: not opposite sides)
if (! opposite(side_qi_p1, side_qk_p1))
{
int const side_pk_q2 = has_pk && has_qk ? side.pk_wrt_q2() : 0;
int const side_pk_p = has_pk ? side.pk_wrt_p1() : 0;
int const side_qk_q = has_qk ? side.qk_wrt_q1() : 0;
bool const q_turns_left = side_qk_q == 1;
bool const block_q = side_qk_p1 == 0
&& ! same(side_qi_p1, side_qk_q)
;
// If Pk at same side as Qi/Qk
// (the "or" is for collinear case)
// or Q is fully collinear && P turns not to left
if (side_pk_p == side_qi_p1
|| side_pk_p == side_qk_p1
|| (side_qi_p1 == 0 && side_qk_p1 == 0 && side_pk_p != -1))
{
if (side_qk_p1 == 0 && side_pk_q1 == 0
&& has_pk && has_qk
&& handle_imperfect_touch(range_p, range_q, side_pk_q2, umbrella_strategy, ti))
{
// If q continues collinearly (opposite) with p, it should be blocked
// but (FP) not if there is just a tiny space in between
return;
}
// Collinear -> lines join, continue
// (#BRL2)
if (side_pk_q2 == 0 && ! block_q)
{
fun::template both_collinear<0, 1>(range_p, range_q, umbrella_strategy,
2, 2, ti);
return;
}
// Collinear opposite case -> block P
// (#BRL4, #BLR8)
if (side_pk_q1 == 0)
{
ti.operations[0].operation = operation_blocked;
// Q turns right -> union (both independent),
// Q turns left -> intersection
ti.operations[1].operation = block_q ? operation_blocked
: q_turns_left ? operation_intersection
: operation_union;
return;
}
// Pk between Qi and Qk
// (#BRL3, #BRL7)
if (between(side_pk_q1, side_pk_q2, side_qk_q))
{
ui_else_iu(q_turns_left, ti);
if (block_q)
{
ti.operations[1].operation = operation_blocked;
}
return;
}
// Pk between Qk and P, so left of Qk (if Q turns right) and vv
// (#BRL1)
if (side_pk_q2 == -side_qk_q)
{
ui_else_iu(! q_turns_left, ti);
ti.touch_only = true;
return;
}
//
// (#BRL5, #BRL9)
if (side_pk_q1 == -side_qk_q)
{
uu_else_ii(! q_turns_left, ti);
if (block_q)
{
ti.operations[1].operation = operation_blocked;
}
else
{
ti.touch_only = true;
}
return;
}
}
else
{
// Pk at other side than Qi/Pk
ti.operations[0].operation = q_turns_left
? operation_intersection
: operation_union;
ti.operations[1].operation = block_q
? operation_blocked
: side_qi_p1 == 1 || side_qk_p1 == 1
? operation_union
: operation_intersection;
if (! block_q)
{
ti.touch_only = true;
}
return;
}
}
else
{
// The qi/qk are opposite to each other, w.r.t. p1
// From left to right or from right to left
int const side_pk_p = has_pk
? fun::verified_side(side.pk_wrt_p1(), range_p, range_p,
umbrella_strategy, 0, 2)
: 0;
bool const right_to_left = side_qk_p1 == 1;
// If p turns into direction of qi (1,2)
if (side_pk_p == side_qi_p1)
{
// Collinear opposite case -> block P
if (side_pk_q1 == 0)
{
ti.operations[0].operation = operation_blocked;
ti.operations[1].operation = right_to_left
? operation_union : operation_intersection;
return;
}
if (side_pk_q1 == side_qk_p1)
{
uu_else_ii(right_to_left, ti);
ti.touch_only = true;
return;
}
}
// If p turns into direction of qk (4,5)
if (side_pk_p == side_qk_p1)
{
int const side_pk_q2 = has_pk ? side.pk_wrt_q2() : 0;
// Collinear case -> lines join, continue
if (side_pk_q2 == 0)
{
both(ti, operation_continue);
return;
}
if (side_pk_q2 == side_qk_p1)
{
ui_else_iu(right_to_left, ti);
ti.touch_only = true;
return;
}
}
// otherwise (3)
ui_else_iu(! right_to_left, ti);
return;
}
}
};
template
<
typename TurnInfo,
typename VerifyPolicy
>
struct equal : public base_turn_handler
{
using fun = turn_info_verification_functions<VerifyPolicy>;
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename IntersectionInfo,
typename DirInfo,
typename SideCalculator,
typename UmbrellaStrategy
>
static inline void apply(UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
TurnInfo& ti,
IntersectionInfo const& info,
DirInfo const& ,
SideCalculator const& side,
UmbrellaStrategy const& umbrella_strategy)
{
// Copy the intersection point in TO direction
assign_point(ti, method_equal, info, non_opposite_to_index(info));
bool const has_pk = ! range_p.is_last_segment();
bool const has_qk = ! range_q.is_last_segment();
int const side_pk_q2 = has_pk && has_qk ? side.pk_wrt_q2() : 0;
int const side_pk_p = has_pk ? side.pk_wrt_p1() : 0;
int const side_qk_p = has_qk ? side.qk_wrt_p1() : 0;
if (has_pk && has_qk && side_pk_p == side_qk_p)
{
// They turn to the same side, or continue both collinearly
// To check for union/intersection, try to check side values
int const side_qk_p2 = side.qk_wrt_p2();
if (opposite(side_qk_p2, side_pk_q2))
{
ui_else_iu(side_pk_q2 == 1, ti);
return;
}
}
// If pk is collinear with qj-qk, they continue collinearly.
// This can be on either side of p1 (== q1), or collinear
// The second condition checks if they do not continue
// oppositely
if (side_pk_q2 == 0 && side_pk_p == side_qk_p)
{
fun::template both_collinear<0, 1>(range_p, range_q, umbrella_strategy, 2, 2, ti);
return;
}
// If they turn to same side (not opposite sides)
if (! opposite(side_pk_p, side_qk_p))
{
// If pk is left of q2 or collinear: p: union, q: intersection
ui_else_iu(side_pk_q2 != -1, ti);
}
else
{
// They turn opposite sides. If p turns left (or collinear),
// p: union, q: intersection
ui_else_iu(side_pk_p != -1, ti);
}
}
};
template
<
typename TurnInfo,
typename VerifyPolicy
>
struct start : public base_turn_handler
{
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename IntersectionInfo,
typename DirInfo,
typename SideCalculator,
typename UmbrellaStrategy
>
static inline bool apply(UniqueSubRange1 const& /*range_p*/,
UniqueSubRange2 const& /*range_q*/,
TurnInfo& ti,
IntersectionInfo const& info,
DirInfo const& dir_info,
SideCalculator const& side,
UmbrellaStrategy const& )
{
if BOOST_GEOMETRY_CONSTEXPR (! VerifyPolicy::use_start_turn)
{
return false;
}
else // else prevents unreachable code warning
{
// Start turns have either how_a = -1, or how_b = -1 (either p leaves or q leaves)
BOOST_GEOMETRY_ASSERT(dir_info.how_a != dir_info.how_b);
BOOST_GEOMETRY_ASSERT(dir_info.how_a == -1 || dir_info.how_b == -1);
BOOST_GEOMETRY_ASSERT(dir_info.how_a == 0 || dir_info.how_b == 0);
if (dir_info.how_b == -1)
{
// p --------------->
// |
// | q q leaves
// v
//
int const side_qj_p1 = side.qj_wrt_p1();
ui_else_iu(side_qj_p1 == -1, ti);
}
else if (dir_info.how_a == -1)
{
// p leaves
int const side_pj_q1 = side.pj_wrt_q1();
ui_else_iu(side_pj_q1 == 1, ti);
}
// Copy intersection point
assign_point_and_correct(ti, method_start, info, dir_info);
return true;
}
}
};
template
<
typename TurnInfo,
typename AssignPolicy
>
struct equal_opposite : public base_turn_handler
{
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename OutputIterator,
typename IntersectionInfo
>
static inline void apply(
UniqueSubRange1 const& /*range_p*/,
UniqueSubRange2 const& /*range_q*/,
/* by value: */ TurnInfo tp,
OutputIterator& out,
IntersectionInfo const& intersection_info)
{
// For equal-opposite segments, normally don't do anything.
if BOOST_GEOMETRY_CONSTEXPR (AssignPolicy::include_opposite)
{
tp.method = method_equal;
for (unsigned int i = 0; i < 2; i++)
{
tp.operations[i].operation = operation_opposite;
}
for (unsigned int i = 0; i < intersection_info.i_info().count; i++)
{
assign_point(tp, method_none, intersection_info.i_info(), i);
*out++ = tp;
}
}
}
};
template
<
typename TurnInfo,
typename VerifyPolicy
>
struct collinear : public base_turn_handler
{
using fun = turn_info_verification_functions<VerifyPolicy>;
template
<
typename IntersectionInfo,
typename UniqueSubRange1,
typename UniqueSubRange2,
typename DirInfo
>
static bool handle_as_equal(IntersectionInfo const& info,
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
DirInfo const& dir_info)
{
if BOOST_GEOMETRY_CONSTEXPR (! VerifyPolicy::use_handle_as_equal)
{
return false;
}
else // else prevents unreachable code warning
{
int const arrival_p = dir_info.arrival[0];
int const arrival_q = dir_info.arrival[1];
if (arrival_p * arrival_q != -1 || info.count != 2)
{
// Code below assumes that either p or q arrives in the other segment
return false;
}
auto const dm = arrival_p == 1
? fun::distance_measure(info.intersections[1], range_q.at(1))
: fun::distance_measure(info.intersections[1], range_p.at(1));
decltype(dm) const zero = 0;
return math::equals(dm, zero);
}
}
/*
Either P arrives within Q (arrival_p == -1) or Q arrives within P.
Typical situation:
^q2
/
^q1
/ ____ ip[1]
//|p1 } this section of p/q is colllinear
q0// | } ____ ip[0]
/ |
/ v
p0 p2
P arrives (at p1) in segment Q (between q0 and q1).
Therefore arrival_p == 1
P (p2) goes to the right (-1). Follow P for intersection, or follow Q for union.
Therefore if (arrival_p==1) and side_p==-1, result = iu
Complete table:
arrival P pk//p1 qk//q1 product case result
1 1 1 CLL1 ui
-1 1 -1 CLL2 iu
1 1 1 CLR1 ui
-1 -1 1 CLR2 ui
1 -1 -1 CRL1 iu
-1 1 -1 CRL2 iu
1 -1 -1 CRR1 iu
-1 -1 1 CRR2 ui
1 0 0 CC1 cc
-1 0 0 CC2 cc
Resulting in the rule:
The arrival-info multiplied by the relevant side delivers the result.
product = arrival * (pk//p1 or qk//q1)
Stated otherwise:
- if P arrives: look at turn P
- if Q arrives: look at turn Q
- if P arrives and P turns left: union for P
- if P arrives and P turns right: intersection for P
- if Q arrives and Q turns left: union for Q (=intersection for P)
- if Q arrives and Q turns right: intersection for Q (=union for P)
*/
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename IntersectionInfo,
typename DirInfo,
typename SidePolicy
>
static inline void apply(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
TurnInfo& ti,
IntersectionInfo const& info,
DirInfo const& dir_info,
SidePolicy const& side)
{
// Copy the intersection point in TO direction
assign_point(ti, method_collinear, info, non_opposite_to_index(info));
int const arrival_p = dir_info.arrival[0];
// Should not be 0, this is checked before
BOOST_GEOMETRY_ASSERT(arrival_p != 0);
bool const has_pk = ! range_p.is_last_segment();
bool const has_qk = ! range_q.is_last_segment();
int const side_p = has_pk ? side.pk_wrt_p1() : 0;
int const side_q = has_qk ? side.qk_wrt_q1() : 0;
// If p arrives, use p, else use q
int const side_p_or_q = arrival_p == 1
? side_p
: side_q
;
// Calculate product according to comments above.
int const product = arrival_p * side_p_or_q;
if (product == 0)
{
both(ti, operation_continue);
}
else
{
ui_else_iu(product == 1, ti);
}
// Calculate remaining distance. If it continues collinearly it is
// measured until the end of the next segment
ti.operations[0].remaining_distance
= side_p == 0 && has_pk
? fun::distance_measure(ti.point, range_p.at(2))
: fun::distance_measure(ti.point, range_p.at(1));
ti.operations[1].remaining_distance
= side_q == 0 && has_qk
? fun::distance_measure(ti.point, range_q.at(2))
: fun::distance_measure(ti.point, range_q.at(1));
}
};
template
<
typename TurnInfo,
typename AssignPolicy
>
struct collinear_opposite : public base_turn_handler
{
private :
/*
arrival P arrival Q pk//p1 qk//q1 case result2 result
--------------------------------------------------------------
1 1 1 -1 CLO1 ix xu
1 1 1 0 CLO2 ix (xx)
1 1 1 1 CLO3 ix xi
1 1 0 -1 CCO1 (xx) xu
1 1 0 0 CCO2 (xx) (xx)
1 1 0 1 CCO3 (xx) xi
1 1 -1 -1 CRO1 ux xu
1 1 -1 0 CRO2 ux (xx)
1 1 -1 1 CRO3 ux xi
-1 1 -1 CXO1 xu
-1 1 0 CXO2 (xx)
-1 1 1 CXO3 xi
1 -1 1 CXO1 ix
1 -1 0 CXO2 (xx)
1 -1 -1 CXO3 ux
*/
template <unsigned int Index, typename IntersectionInfo>
static inline bool set_tp(int side_rk_r, TurnInfo& tp,
IntersectionInfo const& intersection_info)
{
BOOST_STATIC_ASSERT(Index <= 1);
operation_type blocked = operation_blocked;
switch(side_rk_r)
{
case 1 :
// Turning left on opposite collinear: intersection
tp.operations[Index].operation = operation_intersection;
break;
case -1 :
// Turning right on opposite collinear: union
tp.operations[Index].operation = operation_union;
break;
case 0 :
// No turn on opposite collinear: block, do not traverse
// But this "xx" is usually ignored, it is useless to include
// two operations blocked, so the whole point does not need
// to be generated.
// So return false to indicate nothing is to be done.
if BOOST_GEOMETRY_CONSTEXPR (AssignPolicy::include_opposite)
{
tp.operations[Index].operation = operation_opposite;
blocked = operation_opposite;
}
else
{
return false;
}
break;
}
// The other direction is always blocked when collinear opposite
tp.operations[1 - Index].operation = blocked;
// If P arrives within Q, set info on P (which is done above, index=0),
// this turn-info belongs to the second intersection point, index=1
// (see e.g. figure CLO1)
assign_point(tp, method_collinear, intersection_info, 1 - Index);
return true;
}
public:
static inline void empty_transformer(TurnInfo &) {}
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename OutputIterator,
typename IntersectionInfo,
typename SidePolicy
>
static inline void apply(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
// Opposite collinear can deliver 2 intersection points,
TurnInfo const& tp_model,
OutputIterator& out,
IntersectionInfo const& intersection_info,
SidePolicy const& side)
{
apply(range_p, range_q,
tp_model, out, intersection_info, side, empty_transformer);
}
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename OutputIterator,
typename IntersectionInfo,
typename SidePolicy,
typename TurnTransformer
>
static inline void apply(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
// Opposite collinear can deliver 2 intersection points,
TurnInfo const& tp_model,
OutputIterator& out,
IntersectionInfo const& info,
SidePolicy const& side,
TurnTransformer turn_transformer)
{
TurnInfo tp = tp_model;
int const arrival_p = info.d_info().arrival[0];
int const arrival_q = info.d_info().arrival[1];
// If P arrives within Q, there is a turn dependent on P
if ( arrival_p == 1
&& ! range_p.is_last_segment()
&& set_tp<0>(side.pk_wrt_p1(), tp, info.i_info()) )
{
turn_transformer(tp);
*out++ = tp;
}
// If Q arrives within P, there is a turn dependent on Q
if ( arrival_q == 1
&& ! range_q.is_last_segment()
&& set_tp<1>(side.qk_wrt_q1(), tp, info.i_info()) )
{
turn_transformer(tp);
*out++ = tp;
}
if BOOST_GEOMETRY_CONSTEXPR (AssignPolicy::include_opposite)
{
// Handle cases not yet handled above
if ((arrival_q == -1 && arrival_p == 0)
|| (arrival_p == -1 && arrival_q == 0))
{
for (unsigned int i = 0; i < 2; i++)
{
tp.operations[i].operation = operation_opposite;
}
for (unsigned int i = 0; i < info.i_info().count; i++)
{
assign_point(tp, method_collinear, info.i_info(), i);
*out++ = tp;
}
}
}
}
};
template
<
typename TurnInfo
>
struct crosses : public base_turn_handler
{
template <typename IntersectionInfo, typename DirInfo>
static inline void apply(TurnInfo& ti,
IntersectionInfo const& intersection_info,
DirInfo const& dir_info)
{
assign_point(ti, method_crosses, intersection_info, 0);
// In all cases:
// If Q crosses P from left to right
// Union: take P
// Intersection: take Q
// Otherwise: vice versa
int const side_qi_p1 = dir_info.sides.template get<1, 0>();
unsigned int const index = side_qi_p1 == 1 ? 0 : 1;
ti.operations[index].operation = operation_union;
ti.operations[1 - index].operation = operation_intersection;
}
};
struct only_convert : public base_turn_handler
{
template<typename TurnInfo, typename IntersectionInfo>
static inline void apply(TurnInfo& ti, IntersectionInfo const& intersection_info)
{
assign_point(ti, method_none, intersection_info, 0);
ti.operations[0].operation = operation_continue;
ti.operations[1].operation = operation_continue;
}
};
/*!
\brief Policy doing nothing
\details get_turn_info can have an optional policy include extra
truns. By default it does not, and this class is that default.
*/
struct assign_null_policy
{
static bool const include_no_turn = false;
static bool const include_degenerate = false;
static bool const include_opposite = false;
static bool const include_start_turn = false;
};
struct assign_policy_only_start_turns
{
static bool const include_no_turn = false;
static bool const include_degenerate = false;
static bool const include_opposite = false;
static bool const include_start_turn = true;
};
/*!
\brief Turn information: intersection point, method, and turn information
\details Information necessary for traversal phase (a phase
of the overlay process). The information is gathered during the
get_turns (segment intersection) phase.
\tparam AssignPolicy policy to assign extra info,
e.g. to calculate distance from segment's first points
to intersection points.
It also defines if a certain class of points
(degenerate, non-turns) should be included.
*/
template<typename AssignPolicy>
struct get_turn_info
{
// Intersect a segment p with a segment q
// Both p and q are modelled as sub_ranges to provide more points
// to be able to give more information about the turn (left/right)
template
<
typename UniqueSubRange1,
typename UniqueSubRange2,
typename TurnInfo,
typename UmbrellaStrategy,
typename RobustPolicy,
typename OutputIterator
>
static inline OutputIterator apply(
UniqueSubRange1 const& range_p,
UniqueSubRange2 const& range_q,
TurnInfo const& tp_model,
UmbrellaStrategy const& umbrella_strategy,
RobustPolicy const& robust_policy,
OutputIterator out)
{
typedef intersection_info
<
UniqueSubRange1, UniqueSubRange2,
typename TurnInfo::point_type,
UmbrellaStrategy,
RobustPolicy
> inters_info;
inters_info inters(range_p, range_q, umbrella_strategy, robust_policy);
char const method = inters.d_info().how;
if (method == 'd')
{
// Disjoint
return out;
}
// Copy, to copy possibly extended fields
TurnInfo tp = tp_model;
bool const handle_as_touch_interior = method == 'm';
bool const handle_as_cross = method == 'i';
bool handle_as_touch = method == 't';
bool handle_as_equal = method == 'e';
bool const handle_as_collinear = method == 'c';
bool const handle_as_degenerate = method == '0';
bool const handle_as_start = method == 's';
// (angle, from)
bool do_only_convert = method == 'a' || method == 'f';
if (handle_as_start)
{
// It is in some cases necessary to handle a start turn
using handler = start<TurnInfo, verify_policy_aa>;
if (BOOST_GEOMETRY_CONDITION(AssignPolicy::include_start_turn)
&& handler::apply(range_p, range_q, tp,
inters.i_info(), inters.d_info(), inters.sides(),
umbrella_strategy))
{
*out++ = tp;
}
else
{
do_only_convert = true;
}
}
if (handle_as_touch_interior)
{
using handler = touch_interior<TurnInfo, verify_policy_aa>;
if ( inters.d_info().arrival[1] == 1 )
{
// Q arrives
if (handler::handle_as_touch(inters.i_info(), range_p))
{
handle_as_touch = true;
}
else
{
handler::template apply<0>(range_p, range_q, tp, inters.i_info(), inters.d_info(),
inters.sides(), umbrella_strategy);
*out++ = tp;
}
}
else
{
// P arrives, swap p/q
if (handler::handle_as_touch(inters.i_info(), range_q))
{
handle_as_touch = true;
}
else
{
handler::template apply<1>(range_q, range_p, tp, inters.i_info(), inters.d_info(),
inters.swapped_sides(), umbrella_strategy);
*out++ = tp;
}
}
}
if (handle_as_cross)
{
crosses<TurnInfo>::apply(tp, inters.i_info(), inters.d_info());
*out++ = tp;
}
if (handle_as_touch)
{
// Touch: both segments arrive at the intersection point
using handler = touch<TurnInfo, verify_policy_aa>;
handler::apply(range_p, range_q, tp, inters.i_info(), inters.d_info(), inters.sides(),
umbrella_strategy);
*out++ = tp;
}
if (handle_as_collinear)
{
// Collinear
if ( ! inters.d_info().opposite )
{
using handler = collinear<TurnInfo, verify_policy_aa>;
if (inters.d_info().arrival[0] == 0
|| handler::handle_as_equal(inters.i_info(), range_p, range_q, inters.d_info()))
{
// Both segments arrive at the second intersection point
handle_as_equal = true;
}
else
{
handler::apply(range_p, range_q, tp, inters.i_info(),
inters.d_info(), inters.sides());
*out++ = tp;
}
}
else
{
collinear_opposite
<
TurnInfo,
AssignPolicy
>::apply(range_p, range_q, tp, out, inters, inters.sides());
// Zero, or two, turn points are assigned to *out++
}
}
if (handle_as_equal)
{
if ( ! inters.d_info().opposite )
{
// Both equal
// or collinear-and-ending at intersection point
using handler = equal<TurnInfo, verify_policy_aa>;
handler::apply(range_p, range_q, tp,
inters.i_info(), inters.d_info(), inters.sides(),
umbrella_strategy);
if (handle_as_collinear)
{
// Keep info as collinear,
// so override already assigned method
tp.method = method_collinear;
}
*out++ = tp;
}
else
{
equal_opposite
<
TurnInfo,
AssignPolicy
>::apply(range_p, range_q, tp, out, inters);
// Zero, or two, turn points are assigned to *out++
}
}
if ((handle_as_degenerate
&& BOOST_GEOMETRY_CONDITION(AssignPolicy::include_degenerate))
|| (do_only_convert
&& BOOST_GEOMETRY_CONDITION(AssignPolicy::include_no_turn)))
{
if (inters.i_info().count > 0)
{
only_convert::apply(tp, inters.i_info());
*out++ = tp;
}
}
return out;
}
};
}} // namespace detail::overlay
#endif //DOXYGEN_NO_DETAIL
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_TURN_INFO_HPP