GEOS
3.9.1dev
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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. More... | |
Private Member Functions | |
RayCrossingCounter (const RayCrossingCounter &other)=delete | |
RayCrossingCounter & | operator= (const RayCrossingCounter &rhs)=delete |
Private Attributes | |
const geom::Coordinate & | point |
int | crossingCount |
bool | isPointOnSegment |
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 Point-In-Polygon determination, this case allows short-circuiting 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 point-on-segment 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 Y-extent) do not need to be counted. This allows for optimization by indexing.
Definition at line 65 of file RayCrossingCounter.h.
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privatedelete |
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inline |
Definition at line 95 of file RayCrossingCounter.h.
void geos::algorithm::RayCrossingCounter::countSegment | ( | const geom::Coordinate & | p1, |
const geom::Coordinate & | p2 | ||
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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.
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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 Definition at line 120 of file RayCrossingCounter.h.
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
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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 |
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static |
Semantically equal to the above, just different args encoding.
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privatedelete |
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private |
Definition at line 69 of file RayCrossingCounter.h.
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private |
Definition at line 72 of file RayCrossingCounter.h.
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private |
Definition at line 67 of file RayCrossingCounter.h.