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5 <title>Custom Polygon</title>
10 <p><font face="Courier New">/*<br>
11 Copyright 2008 Intel Corporation<br>
13 Use, modification and distribution are subject to the Boost Software License,<br>
14 Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at<br>
15 http://www.boost.org/LICENSE_1_0.txt).<br>
17 #include <boost/polygon/polygon.hpp><br>
18 #include <cassert><br>
19 #include <list><br>
20 namespace gtl = boost::polygon;<br>
21 using namespace boost::polygon::operators;<br><br>
22 //first lets turn our polygon usage code into a generic<br>
23 //function parameterized by polygon type<br>
24 template <typename Polygon><br>
25 void test_polygon() {<br>
26 //lets construct a 10x10 rectangle shaped polygon<br>
27 typedef typename gtl::polygon_traits<Polygon>::point_type Point;<br>
28 Point pts[] = {gtl::construct<Point>(0, 0),<br>
29 gtl::construct<Point>(10, 0),<br>
30 gtl::construct<Point>(10, 10),<br>
31 gtl::construct<Point>(0, 10) };<br>
32 Polygon poly;<br>
33 gtl::set_points(poly, pts, pts+4);<br>
35 //now lets see what we can do with this polygon<br>
36 assert(gtl::area(poly) == 100.0f);<br>
37 assert(gtl::contains(poly, gtl::construct<Point>(5, 5)));<br>
38 assert(!gtl::contains(poly, gtl::construct<Point>(15, 5)));<br>
39 gtl::rectangle_data<int> rect;<br>
40 assert(gtl::extents(rect, poly)); //get bounding box of poly<br>
41 assert(gtl::equivalence(rect, poly)); //hey, that's slick<br>
42 assert(gtl::winding(poly) == gtl::COUNTERCLOCKWISE);<br>
43 assert(gtl::perimeter(poly) == 40.0f);<br>
45 //add 5 to all coords of poly<br>
46 gtl::convolve(poly, gtl::construct<Point>(5, 5));<br>
47 //multiply all coords of poly by 2<br>
48 gtl::scale_up(poly, 2);<br>
49 gtl::set_points(rect, gtl::point_data<int>(10, 10),<br>
50 gtl::point_data<int>(30, 30));<br>
51 assert(gtl::equivalence(poly, rect));<br>
54 //Now lets declare our own polygon class<br>
55 //Oops, we need a point class to support our polygon, lets borrow<br>
56 //the CPoint example<br>
62 //we have to get CPoint working with boost polygon to make our polygon<br>
63 //that uses CPoint working with boost polygon<br>
64 namespace boost { namespace polygon {<br>
65 template <><br>
66 struct geometry_concept<CPoint> { typedef point_concept type; };<br>
67 template <><br>
68 struct point_traits<CPoint> {<br>
69 typedef int coordinate_type;<br>
71 static inline coordinate_type get(const CPoint& point, <br>
72 orientation_2d orient) {<br>
73 if(orient == HORIZONTAL)<br>
74 return point.x;<br>
75 return point.y;<br>
76 }<br>
79 template <><br>
80 struct point_mutable_traits<CPoint> {<br>
81 typedef int coordinate_type;<br>
83 static inline void set(CPoint& point, orientation_2d orient,
85 if(orient == HORIZONTAL)<br>
86 point.x = value;<br>
87 else<br>
88 point.y = value;<br>
89 }<br>
90 static inline CPoint construct(int x_value, int y_value) {<br>
91 CPoint retval;<br>
92 retval.x = x_value;<br>
93 retval.y = y_value; <br>
94 return retval;<br>
95 }<br>
99 //I'm lazy and use the stl everywhere to avoid writing my own classes<br>
100 //my toy polygon is a std::list<CPoint><br>
101 typedef std::list<CPoint> CPolygon;<br>
103 //we need to specialize our polygon concept mapping in boost polygon<br>
104 namespace boost { namespace polygon {<br>
105 //first register CPolygon as a polygon_concept type<br>
106 template <><br>
107 struct geometry_concept<CPolygon>{ typedef polygon_concept type; };<br>
109 template <><br>
110 struct polygon_traits<CPolygon> {<br>
111 typedef int coordinate_type;<br>
112 typedef CPolygon::const_iterator iterator_type;<br>
113 typedef CPoint point_type;<br>
115 // Get the begin iterator<br>
116 static inline iterator_type begin_points(const CPolygon& t) {<br>
117 return t.begin();<br>
118 }<br>
120 // Get the end iterator<br>
121 static inline iterator_type end_points(const CPolygon& t) {<br>
122 return t.end();<br>
123 }<br>
125 // Get the number of sides of the polygon<br>
126 static inline std::size_t size(const CPolygon& t) {<br>
127 return t.size();<br>
128 }<br>
130 // Get the winding direction of the polygon<br>
131 static inline winding_direction winding(const CPolygon& t) {<br>
132 return unknown_winding;<br>
133 }<br>
136 template <><br>
137 struct polygon_mutable_traits<CPolygon> {<br>
138 //expects stl style iterators<br>
139 template <typename iT><br>
140 static inline CPolygon& set_points(CPolygon& t, <br>
141
142 iT input_begin, iT input_end) {<br>
143 t.clear();<br>
144 t.insert(t.end(), input_begin, input_end);<br>
145 return t;<br>
146 }<br>
151 //now there's nothing left to do but test that our polygon<br>
152 //works with library interfaces<br>
154 test_polygon<CPolygon>(); //woot!<br>
160 <table class="docinfo" rules="none" frame="void" id="table1">
162 <col class="docinfo-name"><col class="docinfo-content">
166 <th class="docinfo-name">Copyright:</th>
167 <td>Copyright © Intel Corporation 2008-2010.</td>
170 <th class="docinfo-name">License:</th>
171 <td class="field-body">Distributed under the Boost Software License,
172 Version 1.0. (See accompanying file <tt class="literal">
173 <span class="pre">LICENSE_1_0.txt</span></tt> or copy at
174 <a class="reference" target="_top" href="http://www.boost.org/LICENSE_1_0.txt">
175 http://www.boost.org/LICENSE_1_0.txt</a>)</td>