PostGIS  2.5.0beta2dev-r@@SVN_REVISION@@

◆ edge_point_side()

static int edge_point_side ( const GEOGRAPHIC_EDGE e,
const GEOGRAPHIC_POINT p 
)
static

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 663 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().

664 {
665  POINT3D normal, pt;
666  double w;
667  /* Normal to the plane defined by e */
668  robust_cross_product(&(e->start), &(e->end), &normal);
669  normalize(&normal);
670  geog2cart(p, &pt);
671  /* We expect the dot product of with normal with any vector in the plane to be zero */
672  w = dot_product(&normal, &pt);
673  LWDEBUGF(4,"dot product %.9g",w);
674  if ( FP_IS_ZERO(w) )
675  {
676  LWDEBUG(4, "point is on plane (dot product is zero)");
677  return 0;
678  }
679 
680  if ( w < 0 )
681  return -1;
682  else
683  return 1;
684 }
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:603
void normalize(POINT3D *p)
Normalize to a unit vector.
Definition: lwgeodetic.c:584
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:415
GEOGRAPHIC_POINT start
Definition: lwgeodetic.h:58
GEOGRAPHIC_POINT end
Definition: lwgeodetic.h:59
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesian coordinates on unit sphere.
Definition: lwgeodetic.c:373
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
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