1 /**********************************************************************
2 *
3 * PostGIS - Spatial Types for PostgreSQL
4 * http://postgis.net
5 *
6 * PostGIS is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * PostGIS is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with PostGIS. If not, see <http://www.gnu.org/licenses/>.
18 *
19 **********************************************************************
20 *
21 * Copyright (C) 2010 - Oslandia
22 *
23 **********************************************************************/
24
25
26 /* basic LWTRIANGLE manipulation */
27
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include "liblwgeom_internal.h"
32 #include "lwgeom_log.h"
33
34
35
36 /* construct a new LWTRIANGLE.
37 * use SRID=SRID_UNKNOWN for unknown SRID (will have 8bit type's S = 0)
38 */
39 LWTRIANGLE *
lwtriangle_construct(int32_t srid,GBOX * bbox,POINTARRAY * points)40 lwtriangle_construct(int32_t srid, GBOX *bbox, POINTARRAY *points)
41 {
42 LWTRIANGLE *result;
43
44 result = (LWTRIANGLE*) lwalloc(sizeof(LWTRIANGLE));
45 result->type = TRIANGLETYPE;
46
47 result->flags = points->flags;
48 FLAGS_SET_BBOX(result->flags, bbox?1:0);
49
50 result->srid = srid;
51 result->points = points;
52 result->bbox = bbox;
53
54 return result;
55 }
56
57 LWTRIANGLE *
lwtriangle_construct_empty(int32_t srid,char hasz,char hasm)58 lwtriangle_construct_empty(int32_t srid, char hasz, char hasm)
59 {
60 LWTRIANGLE *result = lwalloc(sizeof(LWTRIANGLE));
61 result->type = TRIANGLETYPE;
62 result->flags = lwflags(hasz,hasm,0);
63 result->srid = srid;
64 result->points = ptarray_construct_empty(hasz, hasm, 1);
65 result->bbox = NULL;
66 return result;
67 }
68
lwtriangle_free(LWTRIANGLE * triangle)69 void lwtriangle_free(LWTRIANGLE *triangle)
70 {
71 if ( ! triangle ) return;
72
73 if (triangle->bbox)
74 lwfree(triangle->bbox);
75
76 if (triangle->points)
77 ptarray_free(triangle->points);
78
79 lwfree(triangle);
80 }
81
printLWTRIANGLE(LWTRIANGLE * triangle)82 void printLWTRIANGLE(LWTRIANGLE *triangle)
83 {
84 if (triangle->type != TRIANGLETYPE)
85 lwerror("printLWTRIANGLE called with something else than a Triangle");
86
87 lwnotice("LWTRIANGLE {");
88 lwnotice(" ndims = %i", (int)FLAGS_NDIMS(triangle->flags));
89 lwnotice(" SRID = %i", (int)triangle->srid);
90 printPA(triangle->points);
91 lwnotice("}");
92 }
93
94 /* @brief Clone LWTRIANGLE object. Serialized point lists are not copied.
95 *
96 * @see ptarray_clone
97 */
98 LWTRIANGLE *
lwtriangle_clone(const LWTRIANGLE * g)99 lwtriangle_clone(const LWTRIANGLE *g)
100 {
101 LWDEBUGF(2, "lwtriangle_clone called with %p", g);
102 return (LWTRIANGLE *)lwline_clone((const LWLINE *)g);
103 }
104
105 void
lwtriangle_force_clockwise(LWTRIANGLE * triangle)106 lwtriangle_force_clockwise(LWTRIANGLE *triangle)
107 {
108 if ( ptarray_isccw(triangle->points) )
109 ptarray_reverse_in_place(triangle->points);
110 }
111
112 int
lwtriangle_is_clockwise(LWTRIANGLE * triangle)113 lwtriangle_is_clockwise(LWTRIANGLE *triangle)
114 {
115 return !ptarray_isccw(triangle->points);
116 }
117
118 void
lwtriangle_release(LWTRIANGLE * lwtriangle)119 lwtriangle_release(LWTRIANGLE *lwtriangle)
120 {
121 lwgeom_release(lwtriangle_as_lwgeom(lwtriangle));
122 }
123
124 /* check coordinate equality */
125 char
lwtriangle_same(const LWTRIANGLE * t1,const LWTRIANGLE * t2)126 lwtriangle_same(const LWTRIANGLE *t1, const LWTRIANGLE *t2)
127 {
128 char r = ptarray_same(t1->points, t2->points);
129 LWDEBUGF(5, "returning %d", r);
130 return r;
131 }
132
133 static char
lwtriangle_is_repeated_points(LWTRIANGLE * triangle)134 lwtriangle_is_repeated_points(LWTRIANGLE *triangle)
135 {
136 char ret;
137 POINTARRAY *pa;
138
139 pa = ptarray_remove_repeated_points(triangle->points, 0.0);
140 ret = ptarray_same(pa, triangle->points);
141 ptarray_free(pa);
142
143 return ret;
144 }
145
146 /*
147 * Construct a triangle from a LWLINE being
148 * the shell
149 * Pointarray from input geom is cloned.
150 * Input line must have 4 points, and be closed.
151 */
152 LWTRIANGLE *
lwtriangle_from_lwline(const LWLINE * shell)153 lwtriangle_from_lwline(const LWLINE *shell)
154 {
155 LWTRIANGLE *ret;
156 POINTARRAY *pa;
157
158 if ( shell->points->npoints != 4 )
159 lwerror("lwtriangle_from_lwline: shell must have exactly 4 points");
160
161 if ( (!FLAGS_GET_Z(shell->flags) && !ptarray_is_closed_2d(shell->points)) ||
162 (FLAGS_GET_Z(shell->flags) && !ptarray_is_closed_3d(shell->points)) )
163 lwerror("lwtriangle_from_lwline: shell must be closed");
164
165 pa = ptarray_clone_deep(shell->points);
166 ret = lwtriangle_construct(shell->srid, NULL, pa);
167
168 if (lwtriangle_is_repeated_points(ret))
169 lwerror("lwtriangle_from_lwline: some points are repeated in triangle");
170
171 return ret;
172 }
173
174 /**
175 * Find the area of the outer ring
176 */
177 double
lwtriangle_area(const LWTRIANGLE * triangle)178 lwtriangle_area(const LWTRIANGLE *triangle)
179 {
180 double area=0.0;
181 uint32_t i;
182 POINT2D p1;
183 POINT2D p2;
184
185 if (! triangle->points->npoints) return area; /* empty triangle */
186
187 for (i=0; i < triangle->points->npoints-1; i++)
188 {
189 getPoint2d_p(triangle->points, i, &p1);
190 getPoint2d_p(triangle->points, i+1, &p2);
191 area += ( p1.x * p2.y ) - ( p1.y * p2.x );
192 }
193
194 area /= 2.0;
195
196 return fabs(area);
197 }
198
199
200 double
lwtriangle_perimeter(const LWTRIANGLE * triangle)201 lwtriangle_perimeter(const LWTRIANGLE *triangle)
202 {
203 if( triangle->points )
204 return ptarray_length(triangle->points);
205 else
206 return 0.0;
207 }
208
209 double
lwtriangle_perimeter_2d(const LWTRIANGLE * triangle)210 lwtriangle_perimeter_2d(const LWTRIANGLE *triangle)
211 {
212 if( triangle->points )
213 return ptarray_length_2d(triangle->points);
214 else
215 return 0.0;
216 }
217