1 #ifndef GEOM_CONVEX_COVER_H
2 #define GEOM_CONVEX_COVER_H
4 /*
5 * convex-cover.h
6 *
7 * Copyright 2006 Nathan Hurst <njh@mail.csse.monash.edu.au>
8 * Copyright 2006 Michael G. Sloan <mgsloan@gmail.com>
9 *
10 * This library is free software; you can redistribute it and/or
11 * modify it either under the terms of the GNU Lesser General Public
12 * License version 2.1 as published by the Free Software Foundation
13 * (the "LGPL") or, at your option, under the terms of the Mozilla
14 * Public License Version 1.1 (the "MPL"). If you do not alter this
15 * notice, a recipient may use your version of this file under either
16 * the MPL or the LGPL.
17 *
18 * You should have received a copy of the LGPL along with this library
19 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * You should have received a copy of the MPL along with this library
22 * in the file COPYING-MPL-1.1
23 *
24 * The contents of this file are subject to the Mozilla Public License
25 * Version 1.1 (the "License"); you may not use this file except in
26 * compliance with the License. You may obtain a copy of the License at
27 * http://www.mozilla.org/MPL/
28 *
29 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
30 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
31 * the specific language governing rights and limitations.
32 *
33 */
35 /** A convex cover is a sequence of convex polygons that completely cover the path. For now a
36 * convex hull class is included here (the convex-hull header is wrong)
37 */
39 #include <2geom/point.h>
40 #include <vector>
42 namespace Geom{
44 /** ConvexHull
45 * A convexhull is a convex region - every point between two points in the convex hull is also in
46 * the convex hull. It is defined by a set of points travelling in a clockwise direction. We require the first point to be top most, and of the topmost, leftmost.
48 * An empty hull has no points, we allow a single point or two points degenerate cases.
50 * We could provide the centroid as a member for efficient direction determination. We can update the
51 * centroid with all operations with the same time complexity as the operation.
52 */
54 class ConvexHull{
55 public: // XXX: should be private :)
56 // extracts the convex hull of boundary. internal use only
57 void find_pivot();
58 void angle_sort();
59 void graham_scan();
60 void graham();
61 public:
62 std::vector<Point> boundary;
63 //Point centroid;
65 void merge(Point p);
66 bool contains_point(Point p);
68 inline Point operator[](int i) const {
70 int l = boundary.size();
71 if(l == 0) return Point();
72 return boundary[i >= 0 ? i % l : (i % l) + l];
73 }
75 /*inline Point &operator[](unsigned i) {
76 int l = boundary.size();
77 if(l == 0) return Point();
78 return boundary[i >= 0 ? i % l : i % l + l];
79 }*/
81 public:
82 ConvexHull() {}
83 ConvexHull(std::vector<Point> const & points) {
84 boundary = points;
85 graham();
86 }
88 template <typename T>
89 ConvexHull(T b, T e) :boundary(b,e) {}
91 ~ConvexHull()
92 {
93 }
95 public:
96 /** Is the convex hull clockwise? We use the definition of clockwise from point.h
97 **/
98 bool is_clockwise() const;
99 bool no_colinear_points() const;
100 bool top_point_first() const;
101 bool meets_invariants() const;
103 // contains no points
104 bool empty() const { return boundary.empty();}
106 // contains exactly one point
107 bool singular() const { return boundary.size() == 1;}
109 // all points are on a line
110 bool linear() const { return boundary.size() == 2;}
111 bool is_degenerate() const;
113 // area of the convex hull
114 double centroid_and_area(Geom::Point& centroid) const;
115 double area() const {
116 Point tmp;
117 return centroid_and_area(tmp);
118 }
120 // furthest point in a direction (lg time)
121 Point const * furthest(Point direction) const;
123 bool is_left(Point p, int n);
124 int find_left(Point p);
125 double narrowest_diameter(Point &a, Point &b, Point &c);
127 };
129 // do two convex hulls intersect?
130 bool intersectp(ConvexHull a, ConvexHull b);
132 std::vector<Point> bridge_points(ConvexHull a, ConvexHull b);
134 // find the convex hull intersection
135 ConvexHull intersection(ConvexHull a, ConvexHull b);
136 ConvexHull sweepline_intersection(ConvexHull const &a, ConvexHull const &b);
138 // find the convex hull of a set of convex hulls
139 ConvexHull merge(ConvexHull a, ConvexHull b);
141 // naive approach
142 ConvexHull graham_merge(ConvexHull a, ConvexHull b);
144 unsigned find_bottom_right(ConvexHull const &a);
146 /*** Arbitrary transform operator.
147 * Take a convex hull and apply an arbitrary convexity preserving transform.
148 * we should be concerned about singular tranforms here.
149 */
150 template <class T> ConvexHull operator*(ConvexHull const &p, T const &m) {
151 ConvexHull pr;
153 pr.boundary.reserve(p.boundary.size());
155 for(unsigned i = 0; i < p.boundary.size(); i++) {
156 pr.boundary.push_back(p.boundary[i]*m);
157 }
158 return pr;
159 }
161 ConvexHull clip(ConvexHull const & ch, Point n, double d);
163 //TODO: reinstate
164 /*class ConvexCover{
165 public:
166 Path const* path;
167 std::vector<ConvexHull> cc;
169 ConvexCover(Path const &sp);
170 };*/
172 };
174 #endif //2GEOM_CONVEX_COVER_H
176 /*
177 Local Variables:
178 mode:c++
179 c-file-style:"stroustrup"
180 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
181 indent-tabs-mode:nil
182 fill-column:99
183 End:
184 */
185 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :