GEOS
3.8.0dev

Counts the number of segments crossed by a horizontal ray extending to the right from a given point, in an incremental fashion. More...
#include <RayCrossingCounter.h>
Public Member Functions  
RayCrossingCounter (const geom::Coordinate &p_point)  
void  countSegment (const geom::Coordinate &p1, const geom::Coordinate &p2) 
Counts a segment. More...  
bool  isOnSegment () 
Reports whether the point lies exactly on one of the supplied segments. More...  
geom::Location  getLocation () 
Gets the Location of the point relative to the ring, polygon or multipolygon from which the processed segments were provided. More...  
bool  isPointInPolygon () 
Tests whether the point lies in or on the ring, polygon or multipolygon from which the processed segments were provided. More...  
Static Public Member Functions  
static geom::Location  locatePointInRing (const geom::Coordinate &p, const geom::CoordinateSequence &ring) 
Determines the Location of a point in a ring. More...  
static geom::Location  locatePointInRing (const geom::Coordinate &p, const std::vector< const geom::Coordinate * > &ring) 
Semantically equal to the above, just different args encoding.  
Counts the number of segments crossed by a horizontal ray extending to the right from a given point, in an incremental fashion.
This can be used to determine whether a point lies in a polygonal geometry. The class determines the situation where the point lies exactly on a segment. When being used for PointInPolygon determination, this case allows shortcircuiting the evaluation.
This class handles polygonal geometries with any number of shells and holes. The orientation of the shell and hole rings is unimportant. In order to compute a correct location for a given polygonal geometry, it is essential that all segments are counted which
The only exception is when the pointonsegment situation is detected, in which case no further processing is required. The implication of the above rule is that segments which can be a priori determined to not touch the ray (i.e. by a test of their bounding box or Yextent) do not need to be counted. This allows for optimization by indexing.
void geos::algorithm::RayCrossingCounter::countSegment  (  const geom::Coordinate &  p1, 
const geom::Coordinate &  p2  
) 
Counts a segment.
p1  an endpoint of the segment 
p2  another endpoint of the segment 
geom::Location geos::algorithm::RayCrossingCounter::getLocation  (  ) 
Gets the Location of the point relative to the ring, polygon or multipolygon from which the processed segments were provided.
This method only determines the correct location if all relevant segments must have been processed.

inline 
Reports whether the point lies exactly on one of the supplied segments.
This method may be called at any time as segments are processed. If the result of this method is true
, no further segments need be supplied, since the result will never change again.
true
if the point lies exactly on a segment bool geos::algorithm::RayCrossingCounter::isPointInPolygon  (  ) 
Tests whether the point lies in or on the ring, polygon or multipolygon from which the processed segments were provided.
This method only determines the correct location if all relevant segments must have been processed.
true
if the point lies in or on the supplied polygon

static 
Determines the Location of a point in a ring.
This method is an exemplar of how to use this class.
p  the point to test 
ring  an array of Coordinates forming a ring 