GRASS GIS 7 Programmer's Manual  7.9.dev(2021)-e5379bbd7
gs_util.c
Go to the documentation of this file.
1 /*!
2  \file lib/ogsf/gs_util.c
3
5
6  GRASS OpenGL gsurf OGSF Library
7
8  (C) 1999-2008 by the GRASS Development Team
9
10  This program is free software under the
11  GNU General Public License (>=v2).
12  Read the file COPYING that comes with GRASS
13  for details.
14
15  \author Bill Brown USACERL, GMSL/University of Illinois
16  \author Doxygenized by Martin Landa <landa.martin gmail.com> (May 2008)
17  */
18
19 #include <stdlib.h>
20 #include <math.h>
21 #include <string.h>
22
23 #include <grass/gis.h>
24 #include <grass/ogsf.h>
25
26 /*!
27  \brief Calculate distance between 2 coordinates
28
29  Units is one of:
30  - "meters",
31  - "miles",
32  - "kilometers",
33  - "feet",
34  - "yards",
35  - "nmiles" (nautical miles),
36  - "rods",
37  - "inches",
38  - "centimeters",
39  - "millimeters",
40  - "micron",
41  - "nanometers",
42  - "cubits",
43  - "hands",
44  - "furlongs",
45  - "chains"
46
47  Default is meters.
48
49  \param from starting point
50  \param to ending point
51  \param units map units
52
53  \return distance between two geographic coordinates in current projection
54  */
55 double GS_geodistance(double *from, double *to, const char *units)
56 {
57  double meters;
58
59  meters = Gs_distance(from, to);
60
61  if (!units) {
62  return (meters);
63  }
64
65  if (strcmp(units, "meters") == 0) {
66  return (meters);
67  }
68
69  if (strcmp(units, "miles") == 0) {
70  return (meters * .0006213712);
71  }
72
73  if (strcmp(units, "kilometers") == 0) {
74  return (meters * .001);
75  }
76
77  if (strcmp(units, "feet") == 0) {
78  return (meters * 3.280840);
79  }
80
81  if (strcmp(units, "yards") == 0) {
82  return (meters * 1.093613);
83  }
84
85  if (strcmp(units, "rods") == 0) {
86  return (meters * .1988388);
87  }
88
89  if (strcmp(units, "inches") == 0) {
90  return (meters * 39.37008);
91  }
92
93  if (strcmp(units, "centimeters") == 0) {
94  return (meters * 100.0);
95  }
96
97  if (strcmp(units, "millimeters") == 0) {
98  return (meters * 1000.0);
99  }
100
101  if (strcmp(units, "micron") == 0) {
102  return (meters * 1000000.0);
103  }
104
105  if (strcmp(units, "nanometers") == 0) {
106  return (meters * 1000000000.0);
107  }
108
109  if (strcmp(units, "cubits") == 0) {
110  return (meters * 2.187227);
111  }
112
113  if (strcmp(units, "hands") == 0) {
114  return (meters * 9.842520);
115  }
116
117  if (strcmp(units, "furlongs") == 0) {
118  return (meters * .004970970);
119  }
120
121  if (strcmp(units, "nmiles") == 0) {
122  /* nautical miles */
123  return (meters * .0005399568);
124  }
125
126  if (strcmp(units, "chains") == 0) {
127  return (meters * .0497097);
128  }
129
130  return (meters);
131 }
132
133 /*!
134  \brief Calculate distance
135
136  \param from 'from' point (X,Y,Z)
137  \param to 'to' point (X,Y,Z)
138
139  \return distance
140  */
141 float GS_distance(float *from, float *to)
142 {
143  float x, y, z;
144
145  x = from[X] - to[X];
146  y = from[Y] - to[Y];
147  z = from[Z] - to[Z];
148
149  return (float)sqrt(x * x + y * y + z * z);
150 }
151
152 /*!
153  \brief Calculate distance in plane
154
155  \param from 'from' point (X,Y)
156  \param to 'to' point (X,Y)
157
158  \return distance
159  */
160 float GS_P2distance(float *from, float *to)
161 {
162  float x, y;
163
164  x = from[X] - to[X];
165  y = from[Y] - to[Y];
166
167  return (float)sqrt(x * x + y * y);
168 }
169
170 /*!
171  \brief Copy vector values
172
173  v1 = v2
174
175  \param[out] v1 first vector
176  \param v2 second vector
177  */
178 void GS_v3eq(float *v1, float *v2)
179 {
180  v1[X] = v2[X];
181  v1[Y] = v2[Y];
182  v1[Z] = v2[Z];
183
184  return;
185 }
186
187 /*!
188  \brief Sum vectors
189
190  v1 += v2
191
192  \param[in,out] v1 first vector
193  \param v2 second vector
194  */
195 void GS_v3add(float *v1, float *v2)
196 {
197  v1[X] += v2[X];
198  v1[Y] += v2[Y];
199  v1[Z] += v2[Z];
200
201  return;
202 }
203
204 /*!
205  \brief Subtract vectors
206
207  v1 -= v2
208
209  \param[in,out] v1 first vector
210  \param v2 second vector
211  */
212 void GS_v3sub(float *v1, float *v2)
213 {
214  v1[X] -= v2[X];
215  v1[Y] -= v2[Y];
216  v1[Z] -= v2[Z];
217
218  return;
219 }
220
221 /*!
222  \brief Multiple vectors
223
224  v1 *= k
225
226  \param[in,out] v1 vector
227  \param k multiplicator
228  */
229 void GS_v3mult(float *v1, float k)
230 {
231  v1[X] *= k;
232  v1[Y] *= k;
233  v1[Z] *= k;
234
235  return;
236 }
237
238 /*!
239  \brief Change v1 so that it is a unit vector (2D)
240
241  \param[in,out] v1 vector
242
243  \return 0 if magnitude of v1 is zero
244  \return 1 if magnitude of v1 > 0
245  */
246 int GS_v3norm(float *v1)
247 {
248  float n;
249
250  n = sqrt(v1[X] * v1[X] + v1[Y] * v1[Y] + v1[Z] * v1[Z]);
251
252  if (n == 0.0) {
253  return (0);
254  }
255
256  v1[X] /= n;
257  v1[Y] /= n;
258  v1[Z] /= n;
259
260  return (1);
261 }
262
263 /*!
264  \brief Change v1 so that it is a unit vector (3D)
265
266  \param[in,out] v1 vector
267
268  \return 0 if magnitude of v1 is zero
269  \return 1 if magnitude of v1 > 0
270  */
271 int GS_v2norm(float *v1)
272 {
273  float n;
274
275  n = sqrt(v1[X] * v1[X] + v1[Y] * v1[Y]);
276
277  if (n == 0.0) {
278  return (0);
279  }
280
281  v1[X] /= n;
282  v1[Y] /= n;
283
284  return (1);
285 }
286
287 /*!
288  \brief Changes v1 so that it is a unit vector
289
290  \param dv1 vector
291
292  \return 0 if magnitude of dv1 is zero
293  \return 1 if magnitude of dv1 > 0
294  */
295 int GS_dv3norm(double *dv1)
296 {
297  double n;
298
299  n = sqrt(dv1[X] * dv1[X] + dv1[Y] * dv1[Y] + dv1[Z] * dv1[Z]);
300
301  if (n == 0.0) {
302  return (0);
303  }
304
305  dv1[X] /= n;
306  dv1[Y] /= n;
307  dv1[Z] /= n;
308
309  return (1);
310 }
311
312
313 /*!
314  \brief Change v2 so that v1v2 is a unit vector
315
316  \param v1 first vector
317  \param v2[in,out] second vector
318
319  \return 0 if magnitude of dx is zero
320  \return 1 if magnitude of dx > 0
321  */
322 int GS_v3normalize(float *v1, float *v2)
323 {
324  float n, dx, dy, dz;
325
326  dx = v2[X] - v1[X];
327  dy = v2[Y] - v1[Y];
328  dz = v2[Z] - v1[Z];
329  n = sqrt(dx * dx + dy * dy + dz * dz);
330
331  if (n == 0.0) {
332  return (0);
333  }
334
335  v2[X] = v1[X] + dx / n;
336  v2[Y] = v1[Y] + dy / n;
337  v2[Z] = v1[Z] + dz / n;
338
339  return (1);
340 }
341
342
343 /*!
344  \brief Get a normalized direction from v1 to v2, store in v3
345
346  \param v1 first vector
347  \param v2 second vector
348  \param[out] v3 output vector
349
350  \return 0 if magnitude of dx is zero
351  \return 1 if magnitude of dx > 0
352  */
353 int GS_v3dir(float *v1, float *v2, float *v3)
354 {
355  float n, dx, dy, dz;
356
357  dx = v2[X] - v1[X];
358  dy = v2[Y] - v1[Y];
359  dz = v2[Z] - v1[Z];
360  n = sqrt(dx * dx + dy * dy + dz * dz);
361
362  if (n == 0.0) {
363  v3[X] = v3[Y] = v3[Z] = 0.0;
364  return (0);
365  }
366
367  v3[X] = dx / n;
368  v3[Y] = dy / n;
369  v3[Z] = dz / n;
370
371  return (1);
372 }
373
374
375 /*!
376  \brief Get a normalized direction from v1 to v2, store in v3 (2D)
377
378  \param v1 first vector
379  \param v2 second vector
380  \param[out] v3 output vector
381
382  \return 0 if magnitude of dx is zero
383  \return 1 if magnitude of dx > 0
384  */
385 void GS_v2dir(float *v1, float *v2, float *v3)
386 {
387  float n, dx, dy;
388
389  dx = v2[X] - v1[X];
390  dy = v2[Y] - v1[Y];
391  n = sqrt(dx * dx + dy * dy);
392
393  v3[X] = dx / n;
394  v3[Y] = dy / n;
395
396  return;
397 }
398
399 /*!
400  \brief Get the cross product v3 = v1 cross v2
401
402  \param v1 first vector
403  \param v2 second vector
404  \param[out] v3 output vector
405  */
406 void GS_v3cross(float *v1, float *v2, float *v3)
407 {
408  v3[X] = (v1[Y] * v2[Z]) - (v1[Z] * v2[Y]);
409  v3[Y] = (v1[Z] * v2[X]) - (v1[X] * v2[Z]);
410  v3[Z] = (v1[X] * v2[Y]) - (v1[Y] * v2[X]);
411
412  return;
413 }
414
415 /*!
416  \brief Magnitude of vector
417
418  \param v1 vector
419  \param[out] mag magnitude value
420  */
421 void GS_v3mag(float *v1, float *mag)
422 {
423  *mag = sqrt(v1[X] * v1[X] + v1[Y] * v1[Y] + v1[Z] * v1[Z]);
424
425  return;
426 }
427
428 /*!
430
431  Initialize by calling with a number nhist to represent number of
432  previous entrys to check, then call with zero as nhist
433
434  \param p1 first point
435  \param p2 second point
436  \param nhist ?
437
438  \return -1 on error
439  \return -2
440  \return 1
441  \return 9
442  */
443 int GS_coordpair_repeats(float *p1, float *p2, int nhist)
444 {
445  static float *entrys = NULL;
446  static int next = 0;
447  static int len = 0;
448  int i;
449
450  if (nhist) {
451  if (entrys) {
452  G_free(entrys);
453  }
454
455  entrys = (float *)G_malloc(4 * nhist * sizeof(float));
456
457  if (!entrys)
458  return (-1);
459
460  len = nhist;
461  next = 0;
462  }
463
464  if (!len) {
465  return (-2);
466  }
467
468  for (i = 0; i < next; i += 4) {
469  if (entrys[i] == p1[0] && entrys[i + 1] == p1[1]
470  && entrys[i + 2] == p2[0] && entrys[i + 3] == p2[1]) {
471  return (1);
472  }
473  }
474
475  if (len == next / 4) {
476  next = 0;
477  }
478
479  entrys[next] = p1[0];
480  entrys[next + 1] = p1[1];
481  entrys[next + 2] = p2[0];
482  entrys[next + 3] = p2[1];
483  next += 4;
484
485  return (0);
486 }
#define G_malloc(n)
Definition: defs/gis.h:112
int GS_v3normalize(float *v1, float *v2)
Change v2 so that v1v2 is a unit vector.
Definition: gs_util.c:322
void GS_v3sub(float *v1, float *v2)
Subtract vectors.
Definition: gs_util.c:212
int GS_v3dir(float *v1, float *v2, float *v3)
Get a normalized direction from v1 to v2, store in v3.
Definition: gs_util.c:353
int GS_v3norm(float *v1)
Change v1 so that it is a unit vector (2D)
Definition: gs_util.c:246
void G_free(void *)
Free allocated memory.
Definition: gis/alloc.c:149
double Gs_distance(double *, double *)
Calculates distance in METERS between two points in current projection (2D)
Definition: gs3.c:84
Sum vectors.
Definition: gs_util.c:195
#define NULL
Definition: ccmath.h:32
#define x
void GS_v3cross(float *v1, float *v2, float *v3)
Get the cross product v3 = v1 cross v2.
Definition: gs_util.c:406
int GS_v2norm(float *v1)
Change v1 so that it is a unit vector (3D)
Definition: gs_util.c:271
void GS_v2dir(float *v1, float *v2, float *v3)
Get a normalized direction from v1 to v2, store in v3 (2D)
Definition: gs_util.c:385
double GS_geodistance(double *from, double *to, const char *units)
Calculate distance between 2 coordinates.
Definition: gs_util.c:55
void GS_v3mult(float *v1, float k)
Multiple vectors.
Definition: gs_util.c:229
#define Z
Definition: ogsf.h:139
#define Y
Definition: ogsf.h:138
int GS_dv3norm(double *dv1)
Changes v1 so that it is a unit vector.
Definition: gs_util.c:295
void GS_v3eq(float *v1, float *v2)
Copy vector values.
Definition: gs_util.c:178
#define X
Definition: ogsf.h:137
float GS_distance(float *from, float *to)
Calculate distance.
Definition: gs_util.c:141
int GS_coordpair_repeats(float *p1, float *p2, int nhist)