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// Boost.Geometry
// Copyright (c) 2020, Oracle and/or its affiliates.
// Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
// Licensed under the Boost Software License version 1.0.
// http://www.boost.org/users/license.html
#ifndef BOOST_GEOMETRY_STRATEGY_CARTESIAN_SIDE_NON_ROBUST_HPP
#define BOOST_GEOMETRY_STRATEGY_CARTESIAN_SIDE_NON_ROBUST_HPP
#include <boost/geometry/util/select_most_precise.hpp>
#include <boost/geometry/util/select_calculation_type.hpp>
#include <boost/geometry/util/precise_math.hpp>
namespace boost { namespace geometry
{
namespace strategy { namespace side
{
/*!
\brief Adaptive precision predicate to check at which side of a segment a point lies:
left of segment (>0), right of segment (< 0), on segment (0).
\ingroup strategies
\tparam CalculationType \tparam_calculation
\details This predicate determines at which side of a segment a point lies
*/
template
<
typename CalculationType = void
>
struct side_non_robust
{
public:
//! \brief Computes double the signed area of the CCW triangle p1, p2, p
#ifndef DOXYGEN_SHOULD_SKIP_THIS
template
<
typename P1,
typename P2,
typename P
>
static inline int apply(P1 const& p1, P2 const& p2, P const& p)
{
typedef typename select_calculation_type_alt
<
CalculationType,
P1,
P2,
P
>::type coordinate_type;
typedef typename select_most_precise
<
coordinate_type,
double
>::type promoted_type;
auto detleft = (promoted_type(get<0>(p1)) - promoted_type(get<0>(p)))
* (promoted_type(get<1>(p2)) - promoted_type(get<1>(p)));
auto detright = (promoted_type(get<1>(p1)) - promoted_type(get<1>(p)))
* (promoted_type(get<0>(p2)) - promoted_type(get<0>(p)));
return detleft > detright ? 1 : (detleft < detright ? -1 : 0 );
}
#endif
};
}} // namespace strategy::side
}} // namespace boost::geometry
#endif // BOOST_GEOMETRY_STRATEGY_CARTESIAN_SIDE_NON_ROBUST_HPP
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