PostGIS  2.5.2dev-r@@SVN_REVISION@@

◆ edge_point_side()

static int edge_point_side ( const GEOGRAPHIC_EDGE e,

Returns -1 if the point is to the left of the plane formed by the edge, 1 if the point is to the right, and 0 if the point is on the plane.

Definition at line 672 of file lwgeodetic.c.

References dot_product(), GEOGRAPHIC_EDGE::end, FP_IS_ZERO, geog2cart(), LWDEBUG, LWDEBUGF, normalize(), robust_cross_product(), GEOGRAPHIC_EDGE::start, and w.

Referenced by edge_point_on_plane(), and sphere_signed_area().

673 {
674  POINT3D normal, pt;
675  double w;
676  /* Normal to the plane defined by e */
677  robust_cross_product(&(e->start), &(e->end), &normal);
678  normalize(&normal);
679  geog2cart(p, &pt);
680  /* We expect the dot product of with normal with any vector in the plane to be zero */
681  w = dot_product(&normal, &pt);
682  LWDEBUGF(4,"dot product %.9g",w);
683  if ( FP_IS_ZERO(w) )
684  {
685  LWDEBUG(4, "point is on plane (dot product is zero)");
686  return 0;
687  }
689  if ( w < 0 )
690  return -1;
691  else
692  return 1;
693 }
void robust_cross_product(const GEOGRAPHIC_POINT *p, const GEOGRAPHIC_POINT *q, POINT3D *a)
Computes the cross product of two vectors using their lat, lng representations.
Definition: lwgeodetic.c:612
void normalize(POINT3D *p)
Normalize to a unit vector.
Definition: lwgeodetic.c:593
char * w
Definition: cu_out_twkb.c:25
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
#define FP_IS_ZERO(A)
static double dot_product(const POINT3D *p1, const POINT3D *p2)
Convert cartesian coordinates on unit sphere to lon/lat coordinates static void cart2ll(const POINT3D...
Definition: lwgeodetic.c:424
Definition: lwgeodetic.h:63
Definition: lwgeodetic.h:64
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesian coordinates on unit sphere.
Definition: lwgeodetic.c:382
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
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