PostGIS  2.5.0beta2dev-r@@SVN_REVISION@@

◆ gbox_pt_outside()

void gbox_pt_outside ( const GBOX gbox,
POINT2D pt_outside 
)

Given a unit geocentric gbox, return a lon/lat (degrees) coordinate point point that is guaranteed to be outside the box (and therefore anything it contains).

Calculate a spherical point that falls outside the geocentric gbox.

Definition at line 1465 of file lwgeodetic.c.

References cart2geog(), gbox_contains_point3d(), GEOGRAPHIC_POINT::lat, GEOGRAPHIC_POINT::lon, LWDEBUG, LWDEBUGF, lwerror(), normalize(), rad2deg, pixval::x, POINT2D::x, POINT3D::x, GBOX::xmax, GBOX::xmin, pixval::y, POINT2D::y, POINT3D::y, GBOX::ymax, GBOX::ymin, POINT3D::z, GBOX::zmax, and GBOX::zmin.

Referenced by CircTreePIP(), geography_point_outside(), lwpoly_covers_point2d(), lwpoly_pt_outside(), and test_tree_circ_pip2().

1466 {
1467  double grow = M_PI / 180.0 / 60.0; /* one arc-minute */
1468  int i;
1469  GBOX ge;
1470  POINT3D corners[8];
1471  POINT3D pt;
1472  GEOGRAPHIC_POINT g;
1473 
1474  while ( grow < M_PI )
1475  {
1476  /* Assign our box and expand it slightly. */
1477  ge = *gbox;
1478  if ( ge.xmin > -1 ) ge.xmin -= grow;
1479  if ( ge.ymin > -1 ) ge.ymin -= grow;
1480  if ( ge.zmin > -1 ) ge.zmin -= grow;
1481  if ( ge.xmax < 1 ) ge.xmax += grow;
1482  if ( ge.ymax < 1 ) ge.ymax += grow;
1483  if ( ge.zmax < 1 ) ge.zmax += grow;
1484 
1485  /* Build our eight corner points */
1486  corners[0].x = ge.xmin;
1487  corners[0].y = ge.ymin;
1488  corners[0].z = ge.zmin;
1489 
1490  corners[1].x = ge.xmin;
1491  corners[1].y = ge.ymax;
1492  corners[1].z = ge.zmin;
1493 
1494  corners[2].x = ge.xmin;
1495  corners[2].y = ge.ymin;
1496  corners[2].z = ge.zmax;
1497 
1498  corners[3].x = ge.xmax;
1499  corners[3].y = ge.ymin;
1500  corners[3].z = ge.zmin;
1501 
1502  corners[4].x = ge.xmax;
1503  corners[4].y = ge.ymax;
1504  corners[4].z = ge.zmin;
1505 
1506  corners[5].x = ge.xmax;
1507  corners[5].y = ge.ymin;
1508  corners[5].z = ge.zmax;
1509 
1510  corners[6].x = ge.xmin;
1511  corners[6].y = ge.ymax;
1512  corners[6].z = ge.zmax;
1513 
1514  corners[7].x = ge.xmax;
1515  corners[7].y = ge.ymax;
1516  corners[7].z = ge.zmax;
1517 
1518  LWDEBUG(4, "trying to use a box corner point...");
1519  for ( i = 0; i < 8; i++ )
1520  {
1521  normalize(&(corners[i]));
1522  LWDEBUGF(4, "testing corner %d: POINT(%.8g %.8g %.8g)", i, corners[i].x, corners[i].y, corners[i].z);
1523  if ( ! gbox_contains_point3d(gbox, &(corners[i])) )
1524  {
1525  LWDEBUGF(4, "corner %d is outside our gbox", i);
1526  pt = corners[i];
1527  normalize(&pt);
1528  cart2geog(&pt, &g);
1529  pt_outside->x = rad2deg(g.lon);
1530  pt_outside->y = rad2deg(g.lat);
1531  LWDEBUGF(4, "returning POINT(%.8g %.8g) as outside point", pt_outside->x, pt_outside->y);
1532  return;
1533  }
1534  }
1535 
1536  /* Try a wider growth to push the corners outside the original box. */
1537  grow *= 2.0;
1538  }
1539 
1540  /* This should never happen! */
1541  lwerror("BOOM! Could not generate outside point!");
1542  return;
1543 }
void normalize(POINT3D *p)
Normalize to a unit vector.
Definition: lwgeodetic.c:584
double y
Definition: liblwgeom.h:342
double xmax
Definition: liblwgeom.h:295
int gbox_contains_point3d(const GBOX *gbox, const POINT3D *pt)
Return true if the point is inside the gbox.
Definition: g_box.c:254
void cart2geog(const POINT3D *p, GEOGRAPHIC_POINT *g)
Convert cartesian coordinates on unit sphere to spherical coordinates.
Definition: lwgeodetic.c:383
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
double x
Definition: liblwgeom.h:342
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:47
double z
Definition: liblwgeom.h:342
double x
Definition: liblwgeom.h:330
double zmax
Definition: liblwgeom.h:299
double ymin
Definition: liblwgeom.h:296
double xmin
Definition: liblwgeom.h:294
#define rad2deg(r)
Definition: lwgeodetic.h:75
double ymax
Definition: liblwgeom.h:297
double y
Definition: liblwgeom.h:330
double zmin
Definition: liblwgeom.h:298
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
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