PostGIS  2.1.10dev-r@@SVN_REVISION@@
int circ_tree_contains_point ( const CIRC_NODE node,
const POINT2D pt,
const POINT2D pt_outside,
int *  on_boundary 
)

Walk the tree and count intersections between the stab line and the edges.

odd => containment, even => no containment. KNOWN PROBLEM: Grazings (think of a sharp point, just touching the stabline) will be counted for one, which will throw off the count.

Definition at line 454 of file lwgeodetic_tree.c.

References circ_node::center, circ_node_is_leaf(), circ_tree_contains_point(), edge_distance_to_point(), edge_intersects(), circ_node::edge_num, GEOGRAPHIC_EDGE::end, FP_LTEQ, geog2cart(), geographic_point_init(), GEOGRAPHIC_POINT::lat, GEOGRAPHIC_POINT::lon, LWDEBUG, LWDEBUGF, circ_node::nodes, circ_node::num_nodes, circ_node::p1, circ_node::p2, PIR_B_TOUCH_RIGHT, PIR_COLINEAR, PIR_INTERSECTS, rad2deg, circ_node::radius, GEOGRAPHIC_EDGE::start, POINT2D::x, and POINT2D::y.

Referenced by circ_tree_contains_point(), circ_tree_distance_tree_internal(), CircTreePIP(), test_tree_circ_pip(), and test_tree_circ_pip2().

455 {
456  GEOGRAPHIC_POINT closest;
457  GEOGRAPHIC_EDGE stab_edge, edge;
458  POINT3D S1, S2, E1, E2;
459  double d;
460  int i, c;
461 
462  /* Construct a stabline edge from our "inside" to our known outside point */
463  geographic_point_init(pt->x, pt->y, &(stab_edge.start));
464  geographic_point_init(pt_outside->x, pt_outside->y, &(stab_edge.end));
465  geog2cart(&(stab_edge.start), &S1);
466  geog2cart(&(stab_edge.end), &S2);
467 
468  LWDEBUG(3, "entered");
469 
470  /*
471  * If the stabline doesn't cross within the radius of a node, there's no
472  * way it can cross.
473  */
474 
475  LWDEBUGF(3, "working on node %p, edge_num %d, radius %g, center POINT(%g %g)", node, node->edge_num, node->radius, rad2deg(node->center.lon), rad2deg(node->center.lat));
476  d = edge_distance_to_point(&stab_edge, &(node->center), &closest);
477  LWDEBUGF(3, "edge_distance_to_point=%g, node_radius=%g", d, node->radius);
478  if ( FP_LTEQ(d, node->radius) )
479  {
480  LWDEBUGF(3,"entering this branch (%p)", node);
481 
482  /* Return the crossing number of this leaf */
483  if ( circ_node_is_leaf(node) )
484  {
485  int inter;
486  LWDEBUGF(3, "leaf node calculation (edge %d)", node->edge_num);
487  geographic_point_init(node->p1->x, node->p1->y, &(edge.start));
488  geographic_point_init(node->p2->x, node->p2->y, &(edge.end));
489  geog2cart(&(edge.start), &E1);
490  geog2cart(&(edge.end), &E2);
491 
492  inter = edge_intersects(&S1, &S2, &E1, &E2);
493 
494  if ( inter & PIR_INTERSECTS )
495  {
496  LWDEBUG(3," got stab line edge_intersection with this edge!");
497  /* To avoid double counting crossings-at-a-vertex, */
498  /* always ignore crossings at "lower" ends of edges*/
499 
500  if ( inter & PIR_B_TOUCH_RIGHT || inter & PIR_COLINEAR )
501  {
502  LWDEBUG(3," rejecting stab line grazing by left-side edge");
503  return 0;
504  }
505  else
506  {
507  LWDEBUG(3," accepting stab line intersection");
508  return 1;
509  }
510  }
511  }
512  /* Or, add up the crossing numbers of all children of this node. */
513  else
514  {
515  c = 0;
516  for ( i = 0; i < node->num_nodes; i++ )
517  {
518  LWDEBUG(3,"internal node calculation");
519  LWDEBUGF(3," calling circ_tree_contains_point on child %d!", i);
520  c += circ_tree_contains_point(node->nodes[i], pt, pt_outside, on_boundary);
521  }
522  return c % 2;
523  }
524  }
525  else
526  {
527  LWDEBUGF(3,"skipping this branch (%p)", node);
528  }
529 
530  return 0;
531 }
Two-point great circle segment from a to b.
Definition: lwgeodetic.h:42
#define PIR_B_TOUCH_RIGHT
Definition: lwgeodetic.h:77
GEOGRAPHIC_POINT center
POINT2D * p2
POINT2D * p1
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:50
#define FP_LTEQ(A, B)
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:33
double x
Definition: liblwgeom.h:284
static int circ_node_is_leaf(const CIRC_NODE *node)
Internal nodes have their point references set to NULL.
#define rad2deg(r)
Definition: lwgeodetic.h:61
GEOGRAPHIC_POINT start
Definition: lwgeodetic.h:44
double edge_distance_to_point(const GEOGRAPHIC_EDGE *e, const GEOGRAPHIC_POINT *gp, GEOGRAPHIC_POINT *closest)
Definition: lwgeodetic.c:1165
int circ_tree_contains_point(const CIRC_NODE *node, const POINT2D *pt, const POINT2D *pt_outside, int *on_boundary)
Walk the tree and count intersections between the stab line and the edges.
GEOGRAPHIC_POINT end
Definition: lwgeodetic.h:45
double y
Definition: liblwgeom.h:284
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesion coordinates on unit sphere.
Definition: lwgeodetic.c:355
int edge_intersects(const POINT3D *A1, const POINT3D *A2, const POINT3D *B1, const POINT3D *B2)
Returns non-zero if edges A and B interact.
Definition: lwgeodetic.c:3096
void geographic_point_init(double lon, double lat, GEOGRAPHIC_POINT *g)
Initialize a geographic point.
Definition: lwgeodetic.c:157
double radius
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:55
#define PIR_COLINEAR
Definition: lwgeodetic.h:74
struct circ_node ** nodes
#define PIR_INTERSECTS
Definition: lwgeodetic.h:73

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