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geometry.index: added segment_intersection algorithm.

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[SVN r84129]
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Adam Wulkiewicz
2013-05-03 20:36:29 +00:00
parent 44084345b9
commit e4e7bd4a28
1 changed files with 141 additions and 0 deletions
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include/boost/geometry/index/detail/algorithms/segment_intersection.hpp Normal file
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// Boost.Geometry Index
//
// n-dimensional box-segment intersection
//
// Copyright (c) 2011-2013 Adam Wulkiewicz, Lodz, Poland.
//
// 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_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP
#define BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP
#include <boost/geometry/index/detail/indexable.hpp>
namespace boost { namespace geometry { namespace index { namespace detail {
template <typename Indexable, typename Point>
struct default_relative_distance_type
{
typedef typename select_most_precise<
typename select_most_precise<
typename traits::coordinate_type<Indexable>::type,
typename traits::coordinate_type<Point>::type
>::type,
float // TODO - use bigger type, calculated from the size of coordinate types
>::type type;
BOOST_MPL_ASSERT_MSG((!::boost::is_unsigned<type>::value),
THIS_TYPE_SHOULDNT_BE_UNSIGNED, (type));
};
namespace dispatch {
template <typename Box, typename Point, size_t I>
struct box_segment_intersection_dim
{
BOOST_STATIC_ASSERT(I < traits::dimension<Box>::value);
BOOST_STATIC_ASSERT(I < traits::dimension<Point>::value);
BOOST_STATIC_ASSERT(traits::dimension<Point>::value == traits::dimension<Box>::value);
typedef typename default_relative_distance_type<Box, Point>::type relative_distance_type;
// WARNING! - relative_distance_type must be IEEE float for this to work
static inline bool apply(Box const& b, Point const& p0, Point const& p1,
relative_distance_type & t_near, relative_distance_type & t_far)
{
relative_distance_type ray_d = geometry::get<I>(p1) - geometry::get<I>(p0);
relative_distance_type tn = ( detail::get<min_corner, I>(b) - geometry::get<I>(p0) ) / ray_d;
relative_distance_type tf = ( detail::get<max_corner, I>(b) - geometry::get<I>(p0) ) / ray_d;
if ( tf < tn )
::std::swap(tn, tf);
if ( t_near < tn )
t_near = tn;
if ( tf < t_far )
t_far = tf;
return 0 <= t_far && t_near <= t_far;
}
};
template <typename Box, typename Point, size_t CurrentDimension>
struct box_segment_intersection
{
BOOST_STATIC_ASSERT(0 < CurrentDimension);
typedef box_segment_intersection_dim<Box, Point, CurrentDimension - 1> for_dim;
typedef typename for_dim::relative_distance_type relative_distance_type;
static inline bool apply(Box const& b, Point const& p0, Point const& p1,
relative_distance_type & t_near, relative_distance_type & t_far)
{
return box_segment_intersection<Box, Point, CurrentDimension - 1>::apply(b, p0, p1, t_near, t_far)
&& for_dim::apply(b, p0, p1, t_near, t_far);
}
};
template <typename Box, typename Point>
struct box_segment_intersection<Box, Point, 1>
{
typedef box_segment_intersection_dim<Box, Point, 0> for_dim;
typedef typename for_dim::relative_distance_type relative_distance_type;
static inline bool apply(Box const& b, Point const& p0, Point const& p1,
relative_distance_type & t_near, relative_distance_type & t_far)
{
return for_dim::apply(b, p0, p1, t_near, t_far);
}
};
template <typename Indexable, typename Point, typename Tag>
struct segment_intersection
{
BOOST_MPL_ASSERT_MSG((false), NOT_IMPLEMENTED_FOR_THIS_GEOMETRY, (segment_intersection));
};
template <typename Indexable, typename Point>
struct segment_intersection<Indexable, Point, point_tag>
{
BOOST_MPL_ASSERT_MSG((false), SEGMENT_POINT_INTERSECTION_UNAVAILABLE, (segment_intersection));
};
template <typename Indexable, typename Point>
struct segment_intersection<Indexable, Point, box_tag>
{
typedef dispatch::box_segment_intersection<Indexable, Point, detail::traits::dimension<Indexable>::value> impl;
typedef typename impl::relative_distance_type relative_distance_type;
static inline bool apply(Indexable const& b, Point const& p0, Point const& p1, relative_distance_type & relative_distance)
{
relative_distance_type t_near = -(::std::numeric_limits<relative_distance_type>::max)();
relative_distance_type t_far = (::std::numeric_limits<relative_distance_type>::max)();
return impl::apply(b, p0, p1, t_near, t_far) &&
(t_near <= 1) &&
( relative_distance = 0 < t_near ? t_near : 0, true );
}
};
} // namespace dispatch
template <typename Indexable, typename Point> inline
bool segment_intersection(Indexable const& b,
Point const& p0,
Point const& p1,
typename default_relative_distance_type<Indexable, Point>::type & relative_distance)
{
// TODO check Indexable and Point concepts
return dispatch::segment_intersection<
Indexable, Point,
typename detail::traits::tag<Indexable>::type
>::apply(b, p0, p1, relative_distance);
}
}}}} // namespace boost::geometry::index::detail
#endif // BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP