source: trunk/third/mozilla/other-licenses/libart_lgpl/art_svp_point.c @ 22325

Revision 22325, 3.3 KB checked in by rbasch, 19 years ago (diff)
This commit was generated by cvs2svn to compensate for changes in r22324, which included commits to RCS files with non-trunk default branches.
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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 **/
41int
42art_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 **/
94double
95art_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
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