PostGIS  2.5.0dev-r@@SVN_REVISION@@
int edge_calculate_gbox_slow ( const GEOGRAPHIC_EDGE e,
GBOX gbox 
)

Definition at line 1309 of file lwgeodetic.c.

References distance(), GEOGRAPHIC_EDGE::end, FP_EQUALS, FP_IS_ZERO, gbox_init_point3d(), gbox_merge_point3d(), geog2cart(), LW_SUCCESS, LWDEBUG, normalize(), sphere_distance(), GEOGRAPHIC_EDGE::start, POINT3D::x, GBOX::xmax, GBOX::xmin, POINT3D::y, GBOX::ymax, GBOX::ymin, POINT3D::z, GBOX::zmax, and GBOX::zmin.

1310 {
1311  int steps = 1000000;
1312  int i;
1313  double dx, dy, dz;
1314  double distance = sphere_distance(&(e->start), &(e->end));
1315  POINT3D pn, p, start, end;
1316 
1317  /* Edge is zero length, just return the naive box */
1318  if ( FP_IS_ZERO(distance) )
1319  {
1320  LWDEBUG(4, "edge is zero length. returning");
1321  geog2cart(&(e->start), &start);
1322  geog2cart(&(e->end), &end);
1323  gbox_init_point3d(&start, gbox);
1324  gbox_merge_point3d(&end, gbox);
1325  return LW_SUCCESS;
1326  }
1327 
1328  /* Edge is antipodal (one point on each side of the globe),
1329  set the box to contain the whole world and return */
1330  if ( FP_EQUALS(distance, M_PI) )
1331  {
1332  LWDEBUG(4, "edge is antipodal. setting to maximum size box, and returning");
1333  gbox->xmin = gbox->ymin = gbox->zmin = -1.0;
1334  gbox->xmax = gbox->ymax = gbox->zmax = 1.0;
1335  return LW_SUCCESS;
1336  }
1337 
1338  /* Walk along the chord between start and end incrementally,
1339  normalizing at each step. */
1340  geog2cart(&(e->start), &start);
1341  geog2cart(&(e->end), &end);
1342  dx = (end.x - start.x)/steps;
1343  dy = (end.y - start.y)/steps;
1344  dz = (end.z - start.z)/steps;
1345  p = start;
1346  gbox->xmin = gbox->xmax = p.x;
1347  gbox->ymin = gbox->ymax = p.y;
1348  gbox->zmin = gbox->zmax = p.z;
1349  for ( i = 0; i < steps; i++ )
1350  {
1351  p.x += dx;
1352  p.y += dy;
1353  p.z += dz;
1354  pn = p;
1355  normalize(&pn);
1356  gbox_merge_point3d(&pn, gbox);
1357  }
1358  return LW_SUCCESS;
1359 }
double sphere_distance(const GEOGRAPHIC_POINT *s, const GEOGRAPHIC_POINT *e)
Given two points on a unit sphere, calculate their distance apart in radians.
Definition: lwgeodetic.c:913
void normalize(POINT3D *p)
Normalize to a unit vector.
Definition: lwgeodetic.c:580
double y
Definition: liblwgeom.h:339
double xmax
Definition: liblwgeom.h:292
#define LW_SUCCESS
Definition: liblwgeom.h:79
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
double x
Definition: liblwgeom.h:339
int gbox_init_point3d(const POINT3D *p, GBOX *gbox)
Initialize a GBOX using the values of the point.
Definition: g_box.c:246
#define FP_IS_ZERO(A)
double z
Definition: liblwgeom.h:339
double zmax
Definition: liblwgeom.h:296
double ymin
Definition: liblwgeom.h:293
double xmin
Definition: liblwgeom.h:291
GEOGRAPHIC_POINT start
Definition: lwgeodetic.h:58
int gbox_merge_point3d(const POINT3D *p, GBOX *gbox)
Update the GBOX to be large enough to include itself and the new point.
Definition: g_box.c:235
double ymax
Definition: liblwgeom.h:294
GEOGRAPHIC_POINT end
Definition: lwgeodetic.h:59
Datum distance(PG_FUNCTION_ARGS)
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesion coordinates on unit sphere.
Definition: lwgeodetic.c:369
double zmin
Definition: liblwgeom.h:295
#define FP_EQUALS(A, B)

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