75 lines
2.7 KiB
C++
75 lines
2.7 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2021 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_ALGORITHMS_DETAIL_OVERLAY_APPROXIMATELY_EQUALS_HPP
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#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPROXIMATELY_EQUALS_HPP
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#include <boost/geometry/core/access.hpp>
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#include <boost/geometry/util/math.hpp>
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#include <boost/geometry/util/select_coordinate_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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#ifndef DOXYGEN_NO_DETAIL
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namespace detail { namespace overlay
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{
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// Value for approximately_equals used by get_cluster and sort_by_side
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// This is an "epsilon_multiplier" and, therefore, multiplied the epsilon
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// belonging to the used floating point type with this value.
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template <typename T>
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struct common_approximately_equals_epsilon_multiplier
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{
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static T value()
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{
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// The value is (a bit) arbitrary. For sort_by_side it should be large
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// enough to not take a point which is too close by, to calculate the
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// side value correctly. For get_cluster it is arbitrary as well, points
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// close to each other should form a cluster, which is also important
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// for subsequent side calculations. Points too far apart should not be
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// clustered.
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//
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// The value of 100 is currently considered as a sweet spot.
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// If the value changes (as of 2023-09-13):
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// 10: too small, failing unit test(s):
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// - union: issue_1108
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// 50: this would be fine, no tests failing
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// 1000: this would be fine, no tests failing
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return T(100);
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}
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};
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template <typename Point1, typename Point2, typename E>
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inline bool approximately_equals(Point1 const& a, Point2 const& b,
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E const& epsilon_multiplier)
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{
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using coor_t = typename select_coordinate_type<Point1, Point2>::type;
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using calc_t = typename geometry::select_most_precise<coor_t, E>::type;
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calc_t const& a0 = geometry::get<0>(a);
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calc_t const& b0 = geometry::get<0>(b);
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calc_t const& a1 = geometry::get<1>(a);
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calc_t const& b1 = geometry::get<1>(b);
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math::detail::equals_factor_policy<calc_t> policy(a0, b0, a1, b1);
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policy.multiply_epsilon(epsilon_multiplier);
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return math::detail::equals_by_policy(a0, b0, policy)
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&& math::detail::equals_by_policy(a1, b1, policy);
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}
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}} // namespace detail::overlay
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#endif //DOXYGEN_NO_DETAIL
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPROXIMATELY_EQUALS_HPP
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