1 | // Boost.Geometry Index |
2 | // |
3 | // n-dimensional box-segment intersection |
4 | // |
5 | // Copyright (c) 2011-2014 Adam Wulkiewicz, Lodz, Poland. |
6 | // |
7 | // Use, modification and distribution is subject to the Boost Software License, |
8 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
9 | // http://www.boost.org/LICENSE_1_0.txt) |
10 | |
11 | #ifndef BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP |
12 | #define BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP |
13 | |
14 | namespace boost { namespace geometry { namespace index { namespace detail { |
15 | |
16 | //template <typename Indexable, typename Point> |
17 | //struct default_relative_distance_type |
18 | //{ |
19 | // typedef typename select_most_precise< |
20 | // typename select_most_precise< |
21 | // typename coordinate_type<Indexable>::type, |
22 | // typename coordinate_type<Point>::type |
23 | // >::type, |
24 | // float // TODO - use bigger type, calculated from the size of coordinate types |
25 | // >::type type; |
26 | // |
27 | // |
28 | // BOOST_MPL_ASSERT_MSG((!::boost::is_unsigned<type>::value), |
29 | // THIS_TYPE_SHOULDNT_BE_UNSIGNED, (type)); |
30 | //}; |
31 | |
32 | namespace dispatch { |
33 | |
34 | template <typename Box, typename Point, size_t I> |
35 | struct box_segment_intersection_dim |
36 | { |
37 | BOOST_STATIC_ASSERT(0 <= dimension<Box>::value); |
38 | BOOST_STATIC_ASSERT(0 <= dimension<Point>::value); |
39 | BOOST_STATIC_ASSERT(I < size_t(dimension<Box>::value)); |
40 | BOOST_STATIC_ASSERT(I < size_t(dimension<Point>::value)); |
41 | BOOST_STATIC_ASSERT(dimension<Point>::value == dimension<Box>::value); |
42 | |
43 | // WARNING! - RelativeDistance must be IEEE float for this to work |
44 | |
45 | template <typename RelativeDistance> |
46 | static inline bool apply(Box const& b, Point const& p0, Point const& p1, |
47 | RelativeDistance & t_near, RelativeDistance & t_far) |
48 | { |
49 | RelativeDistance ray_d = geometry::get<I>(p1) - geometry::get<I>(p0); |
50 | RelativeDistance tn = ( geometry::get<min_corner, I>(b) - geometry::get<I>(p0) ) / ray_d; |
51 | RelativeDistance tf = ( geometry::get<max_corner, I>(b) - geometry::get<I>(p0) ) / ray_d; |
52 | if ( tf < tn ) |
53 | ::std::swap(tn, tf); |
54 | |
55 | if ( t_near < tn ) |
56 | t_near = tn; |
57 | if ( tf < t_far ) |
58 | t_far = tf; |
59 | |
60 | return 0 <= t_far && t_near <= t_far; |
61 | } |
62 | }; |
63 | |
64 | template <typename Box, typename Point, size_t CurrentDimension> |
65 | struct box_segment_intersection |
66 | { |
67 | BOOST_STATIC_ASSERT(0 < CurrentDimension); |
68 | |
69 | typedef box_segment_intersection_dim<Box, Point, CurrentDimension - 1> for_dim; |
70 | |
71 | template <typename RelativeDistance> |
72 | static inline bool apply(Box const& b, Point const& p0, Point const& p1, |
73 | RelativeDistance & t_near, RelativeDistance & t_far) |
74 | { |
75 | return box_segment_intersection<Box, Point, CurrentDimension - 1>::apply(b, p0, p1, t_near, t_far) |
76 | && for_dim::apply(b, p0, p1, t_near, t_far); |
77 | } |
78 | }; |
79 | |
80 | template <typename Box, typename Point> |
81 | struct box_segment_intersection<Box, Point, 1> |
82 | { |
83 | typedef box_segment_intersection_dim<Box, Point, 0> for_dim; |
84 | |
85 | template <typename RelativeDistance> |
86 | static inline bool apply(Box const& b, Point const& p0, Point const& p1, |
87 | RelativeDistance & t_near, RelativeDistance & t_far) |
88 | { |
89 | return for_dim::apply(b, p0, p1, t_near, t_far); |
90 | } |
91 | }; |
92 | |
93 | template <typename Indexable, typename Point, typename Tag> |
94 | struct segment_intersection |
95 | { |
96 | BOOST_MPL_ASSERT_MSG((false), NOT_IMPLEMENTED_FOR_THIS_GEOMETRY, (segment_intersection)); |
97 | }; |
98 | |
99 | template <typename Indexable, typename Point> |
100 | struct segment_intersection<Indexable, Point, point_tag> |
101 | { |
102 | BOOST_MPL_ASSERT_MSG((false), SEGMENT_POINT_INTERSECTION_UNAVAILABLE, (segment_intersection)); |
103 | }; |
104 | |
105 | template <typename Indexable, typename Point> |
106 | struct segment_intersection<Indexable, Point, box_tag> |
107 | { |
108 | typedef dispatch::box_segment_intersection<Indexable, Point, dimension<Indexable>::value> impl; |
109 | |
110 | template <typename RelativeDistance> |
111 | static inline bool apply(Indexable const& b, Point const& p0, Point const& p1, RelativeDistance & relative_distance) |
112 | { |
113 | |
114 | // TODO: this ASSERT CHECK is wrong for user-defined CoordinateTypes! |
115 | |
116 | static const bool check = !::boost::is_integral<RelativeDistance>::value; |
117 | BOOST_MPL_ASSERT_MSG(check, RELATIVE_DISTANCE_MUST_BE_FLOATING_POINT_TYPE, (RelativeDistance)); |
118 | |
119 | RelativeDistance t_near = -(::std::numeric_limits<RelativeDistance>::max)(); |
120 | RelativeDistance t_far = (::std::numeric_limits<RelativeDistance>::max)(); |
121 | |
122 | return impl::apply(b, p0, p1, t_near, t_far) && |
123 | (t_near <= 1) && |
124 | ( relative_distance = 0 < t_near ? t_near : 0, true ); |
125 | } |
126 | }; |
127 | |
128 | } // namespace dispatch |
129 | |
130 | template <typename Indexable, typename Point, typename RelativeDistance> inline |
131 | bool segment_intersection(Indexable const& b, |
132 | Point const& p0, |
133 | Point const& p1, |
134 | RelativeDistance & relative_distance) |
135 | { |
136 | // TODO check Indexable and Point concepts |
137 | |
138 | return dispatch::segment_intersection< |
139 | Indexable, Point, |
140 | typename tag<Indexable>::type |
141 | >::apply(b, p0, p1, relative_distance); |
142 | } |
143 | |
144 | }}}} // namespace boost::geometry::index::detail |
145 | |
146 | #endif // BOOST_GEOMETRY_INDEX_DETAIL_ALGORITHMS_SEGMENT_INTERSECTION_HPP |
147 | |