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118 lines
3.5 KiB
118 lines
3.5 KiB
// Boost.Geometry (aka GGL, Generic Geometry Library) |
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// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands. |
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// Copyright (c) 2008-2011 Bruno Lalande, Paris, France. |
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// Copyright (c) 2009-2011 Mateusz Loskot, London, UK. |
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// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library |
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// (geolib/GGL), copyright (c) 1995-2010 Geodan, 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_STRATEGIES_CARTESIAN_SIDE_BY_TRIANGLE_HPP |
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#define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_SIDE_BY_TRIANGLE_HPP |
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#include <boost/mpl/if.hpp> |
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#include <boost/type_traits.hpp> |
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#include <boost/geometry/core/access.hpp> |
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#include <boost/geometry/util/select_coordinate_type.hpp> |
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#include <boost/geometry/strategies/side.hpp> |
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namespace boost { namespace geometry |
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{ |
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namespace strategy { namespace side |
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{ |
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/*! |
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\brief Check at which side of a segment a point lies: |
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left of segment (> 0), right of segment (< 0), on segment (0) |
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\ingroup strategies |
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\tparam CalculationType \tparam_calculation |
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*/ |
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template <typename CalculationType = void> |
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class side_by_triangle |
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{ |
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public : |
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// Template member function, because it is not always trivial |
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// or convenient to explicitly mention the typenames in the |
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// strategy-struct itself. |
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// Types can be all three different. Therefore it is |
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// not implemented (anymore) as "segment" |
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template <typename P1, typename P2, typename P> |
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static inline int apply(P1 const& p1, P2 const& p2, P const& p) |
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{ |
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typedef typename boost::mpl::if_c |
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< |
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boost::is_void<CalculationType>::type::value, |
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typename select_most_precise |
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< |
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typename select_most_precise |
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< |
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typename coordinate_type<P1>::type, |
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typename coordinate_type<P2>::type |
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>::type, |
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typename coordinate_type<P>::type |
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>::type, |
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CalculationType |
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>::type coordinate_type; |
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//std::cout << "side: " << typeid(coordinate_type).name() << std::endl; |
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coordinate_type const x = get<0>(p); |
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coordinate_type const y = get<1>(p); |
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coordinate_type const sx1 = get<0>(p1); |
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coordinate_type const sy1 = get<1>(p1); |
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coordinate_type const sx2 = get<0>(p2); |
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coordinate_type const sy2 = get<1>(p2); |
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// Promote float->double, small int->int |
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typedef typename select_most_precise |
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< |
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coordinate_type, |
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double |
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>::type promoted_type; |
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promoted_type const dx = sx2 - sx1; |
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promoted_type const dy = sy2 - sy1; |
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promoted_type const dpx = x - sx1; |
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promoted_type const dpy = y - sy1; |
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promoted_type const s = dx * dpy - dy * dpx; |
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promoted_type const zero = promoted_type(); |
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return math::equals(s, zero) ? 0 |
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: s > zero ? 1 |
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: -1; |
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} |
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}; |
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#ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS |
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namespace services |
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{ |
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template <typename CalculationType> |
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struct default_strategy<cartesian_tag, CalculationType> |
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{ |
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typedef side_by_triangle<CalculationType> type; |
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}; |
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} |
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#endif |
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}} // namespace strategy::side |
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}} // namespace boost::geometry |
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#endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_SIDE_BY_TRIANGLE_HPP
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