1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1999 Raph Levien
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
19
20 #include "config.h"
21 #include "art_svp_point.h"
22
23 #include <math.h>
24 #include "art_misc.h"
25
26 #include "art_svp.h"
27
28 /* Determine whether a point is inside, or near, an svp. */
29
30 /* return winding number of point wrt svp */
31 /**
32 * art_svp_point_wind: Determine winding number of a point with respect to svp.
33 * @svp: The svp.
34 * @x: The X coordinate of the point.
35 * @y: The Y coordinate of the point.
36 *
37 * Determine the winding number of the point @x, @y with respect to @svp.
38 *
39 * Return value: the winding number.
40 **/
41 int
art_svp_point_wind(ArtSVP * svp,double x,double y)42 art_svp_point_wind (ArtSVP *svp, double x, double y)
43 {
44 int i, j;
45 int wind = 0;
46
47 for (i = 0; i < svp->n_segs; i++)
48 {
49 ArtSVPSeg *seg = &svp->segs[i];
50
51 if (seg->bbox.y0 > y)
52 break;
53
54 if (seg->bbox.y1 > y)
55 {
56 if (seg->bbox.x1 < x)
57 wind += seg->dir ? 1 : -1;
58 else if (seg->bbox.x0 <= x)
59 {
60 double x0, y0, x1, y1, dx, dy;
61
62 for (j = 0; j < seg->n_points - 1; j++)
63 {
64 if (seg->points[j + 1].y > y)
65 break;
66 }
67 x0 = seg->points[j].x;
68 y0 = seg->points[j].y;
69 x1 = seg->points[j + 1].x;
70 y1 = seg->points[j + 1].y;
71
72 dx = x1 - x0;
73 dy = y1 - y0;
74 if ((x - x0) * dy > (y - y0) * dx)
75 wind += seg->dir ? 1 : -1;
76 }
77 }
78 }
79
80 return wind;
81 }
82
83 /**
84 * art_svp_point_dist: Determine distance between point and svp.
85 * @svp: The svp.
86 * @x: The X coordinate of the point.
87 * @y: The Y coordinate of the point.
88 *
89 * Determines the distance of the point @x, @y to the closest edge in
90 * @svp. A large number is returned if @svp is empty.
91 *
92 * Return value: the distance.
93 **/
94 double
art_svp_point_dist(ArtSVP * svp,double x,double y)95 art_svp_point_dist (ArtSVP *svp, double x, double y)
96 {
97 int i, j;
98 double dist_sq;
99 double best_sq = -1;
100
101 for (i = 0; i < svp->n_segs; i++)
102 {
103 ArtSVPSeg *seg = &svp->segs[i];
104 for (j = 0; j < seg->n_points - 1; j++)
105 {
106 double x0 = seg->points[j].x;
107 double y0 = seg->points[j].y;
108 double x1 = seg->points[j + 1].x;
109 double y1 = seg->points[j + 1].y;
110
111 double dx = x1 - x0;
112 double dy = y1 - y0;
113
114 double dxx0 = x - x0;
115 double dyy0 = y - y0;
116
117 double dot = dxx0 * dx + dyy0 * dy;
118
119 if (dot < 0)
120 dist_sq = dxx0 * dxx0 + dyy0 * dyy0;
121 else
122 {
123 double rr = dx * dx + dy * dy;
124
125 if (dot > rr)
126 dist_sq = (x - x1) * (x - x1) + (y - y1) * (y - y1);
127 else
128 {
129 double perp = (y - y0) * dx - (x - x0) * dy;
130
131 dist_sq = perp * perp / rr;
132 }
133 }
134 if (best_sq < 0 || dist_sq < best_sq)
135 best_sq = dist_sq;
136 }
137 }
138
139 if (best_sq >= 0)
140 return sqrt (best_sq);
141 else
142 return 1e12;
143 }
144
145