1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1998-2000 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* Vector path set operations, over sorted vpaths. */
#include "config.h"
#include "art_svp_ops.h"
#include "art_misc.h"
#include "art_svp.h"
#include "art_vpath.h"
#include "art_svp_vpath.h"
#include "art_svp.h"
#ifdef ART_USE_NEW_INTERSECTOR
#include "art_svp_intersect.h"
#else
#include "art_svp_wind.h"
#endif
#include "art_vpath_svp.h"
/* Merge the segments of the two svp's. The resulting svp will share
segments with args passed in, so be super-careful with the
allocation. */
/**
* art_svp_merge: Merge the segments of two svp's.
* @svp1: One svp to merge.
* @svp2: The other svp to merge.
*
* Merges the segments of two SVP's into a new one. The resulting
* #ArtSVP data structure will share the segments of the argument
* svp's, so it is probably a good idea to free it shallowly,
* especially if the arguments will be freed with art_svp_free().
*
* Return value: The merged #ArtSVP.
**/
static ArtSVP *
art_svp_merge (const ArtSVP *svp1, const ArtSVP *svp2)
{
ArtSVP *svp_new;
gint ix;
gint ix1, ix2;
svp_new = (ArtSVP *)art_alloc (sizeof (ArtSVP) +
(svp1->n_segs + svp2->n_segs - 1) *
sizeof (ArtSVPSeg));
ix1 = 0;
ix2 = 0;
for (ix = 0; ix < svp1->n_segs + svp2->n_segs; ix++)
{
if (ix1 < svp1->n_segs &&
(ix2 == svp2->n_segs ||
art_svp_seg_compare (&svp1->segs[ix1], &svp2->segs[ix2]) < 1))
svp_new->segs[ix] = svp1->segs[ix1++];
else
svp_new->segs[ix] = svp2->segs[ix2++];
}
svp_new->n_segs = ix;
return svp_new;
}
#ifndef ART_USE_NEW_INTERSECTOR
static ArtSVP *
art_svp_merge_perturbed (const ArtSVP *svp1, const ArtSVP *svp2)
{
ArtVpath *vpath1, *vpath2;
ArtVpath *vpath1_p, *vpath2_p;
ArtSVP *svp1_p, *svp2_p;
ArtSVP *svp_new;
vpath1 = art_vpath_from_svp (svp1);
vpath1_p = art_vpath_perturb (vpath1);
art_free (vpath1);
svp1_p = art_svp_from_vpath (vpath1_p);
art_free (vpath1_p);
vpath2 = art_vpath_from_svp (svp2);
vpath2_p = art_vpath_perturb (vpath2);
art_free (vpath2);
svp2_p = art_svp_from_vpath (vpath2_p);
art_free (vpath2_p);
svp_new = art_svp_merge (svp1_p, svp2_p);
art_free (svp1_p);
art_free (svp2_p);
return svp_new;
}
#endif
/* Compute the intersection of two vector paths.
Status of this routine:
Basic correctness: Seems to work.
Numerical stability: We cheat (adding random perturbation). Thus,
it seems very likely that no numerical stability problems will be
seen in practice.
Speed: Would be better if we didn't go to unsorted vector path
and back to add the perturbation.
Precision: The perturbation fuzzes the coordinates slightly. In
cases of butting segments, razor thin long isolated segments may
appear.
*/
/**
* art_svp_intersect: Compute the intersection of two sorted vector paths.
* @svp1: One sorted vector path.
* @svp2: The other sorted vector path.
*
* Computes the intersection of the two argument svp's. Given two
* svp's with winding numbers of 0 and 1 everywhere, the resulting
* winding number will be 1 where both of the argument svp's has a
* winding number 1, 0 otherwise. The result is newly allocated.
*
* Currently, this routine has accuracy problems pending the
* implementation of the new intersector.
*
* Return value: The intersection of @svp1 and @svp2.
**/
ArtSVP *
art_svp_intersect (const ArtSVP *svp1, const ArtSVP *svp2)
{
#ifdef ART_USE_NEW_INTERSECTOR
ArtSVP *svp3, *svp_new;
ArtSvpWriter *swr;
svp3 = art_svp_merge (svp1, svp2);
swr = art_svp_writer_rewind_new (ART_WIND_RULE_INTERSECT);
art_svp_intersector (svp3, swr);
svp_new = art_svp_writer_rewind_reap (swr);
art_free (svp3); /* shallow free because svp3 contains shared segments */
return svp_new;
#else
ArtSVP *svp3, *svp4, *svp_new;
svp3 = art_svp_merge_perturbed (svp1, svp2);
svp4 = art_svp_uncross (svp3);
art_svp_free (svp3);
svp_new = art_svp_rewind_uncrossed (svp4, ART_WIND_RULE_INTERSECT);
art_svp_free (svp4);
return svp_new;
#endif
}
|
