1 // Boost.Geometry (aka GGL, Generic Geometry Library)
2 // QuickBook Example
3
4 // Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands.
5
6 // Use, modification and distribution is subject to the Boost Software License,
7 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
8 // http://www.boost.org/LICENSE_1_0.txt)
9
10 //[reverse
11 //` Shows how to reverse a ring or polygon
12
13 #include <iostream>
14
15 #include <boost/geometry.hpp>
16 #include <boost/geometry/geometries/polygon.hpp>
17 #include <boost/geometry/geometries/ring.hpp>
18 #include <boost/geometry/geometries/adapted/boost_tuple.hpp>
19
BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)20 BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)
21
22 #include <boost/assign.hpp>
23
24 int main()
25 {
26 using boost::assign::tuple_list_of;
27
28 typedef boost::tuple<int, int> point;
29 typedef boost::geometry::model::polygon<point> polygon;
30 typedef boost::geometry::model::ring<point> ring;
31
32
33 polygon poly;
34 boost::geometry::exterior_ring(poly) = tuple_list_of(0, 0)(0, 9)(10, 10)(0, 0);
35 boost::geometry::interior_rings(poly).push_back(tuple_list_of(1, 2)(4, 6)(2, 8)(1, 2));
36
37 double area_before = boost::geometry::area(poly);
38 boost::geometry::reverse(poly);
39 double area_after = boost::geometry::area(poly);
40 std::cout << boost::geometry::dsv(poly) << std::endl;
41 std::cout << area_before << " -> " << area_after << std::endl;
42
43 ring r = tuple_list_of(0, 0)(0, 9)(8, 8)(0, 0);
44
45 area_before = boost::geometry::area(r);
46 boost::geometry::reverse(r);
47 area_after = boost::geometry::area(r);
48 std::cout << boost::geometry::dsv(r) << std::endl;
49 std::cout << area_before << " -> " << area_after << std::endl;
50
51 return 0;
52 }
53
54 //]
55
56
57 //[reverse_output
58 /*`
59 Output:
60 [pre
61 (((0, 0), (10, 10), (0, 9), (0, 0)), ((1, 2), (2, 8), (4, 6), (1, 2)))
62 38 -> -38
63 ((0, 0), (8, 8), (0, 9), (0, 0))
64 36 -> -36
65 ]
66 */
67 //]
68