geos::algorithm::Intersection Class Reference

Functions to compute intersection points between lines and line segments. More...

#include <Intersection.h>

Static Public Member Functions
static geom::CoordinateXY	intersection (const geom::CoordinateXY &p1, const geom::CoordinateXY &p2, const geom::CoordinateXY &q1, const geom::CoordinateXY &q2)
	Computes the intersection point of two lines. If the lines are parallel or collinear this case is detected and null is returned. More...
static geom::CoordinateXY	intersectionLineSegment (const geom::CoordinateXY &line1, const geom::CoordinateXY &line2, const geom::CoordinateXY &seg1, const geom::CoordinateXY &seg2)

Detailed Description

Functions to compute intersection points between lines and line segments.

In general it is not possible to compute the intersection point of two lines exactly, due to numerical roundoff. This is particularly true when the lines are nearly parallel. These routines uses numerical conditioning on the input values to ensure that the computed value is very close to the correct value.

The Z-ordinate is ignored, and not populated.

Member Function Documentation

intersection()

static geom::CoordinateXY geos::algorithm::Intersection::intersection ( const geom::CoordinateXY &  p1, const geom::CoordinateXY &  p2, const geom::CoordinateXY &  q1, const geom::CoordinateXY &  q2  )

static

Computes the intersection point of two lines. If the lines are parallel or collinear this case is detected and null is returned.

Parameters

p1	an endpoint of line 1
p2	an endpoint of line 1
q1	an endpoint of line 2
q2	an endpoint of line 2

Returns

the intersection point between the lines, if there is one, or null if the lines are parallel or collinear

See also

CGAlgorithmsDD::intersection(Coordinate, Coordinate, Coordinate, Coordinate)

intersectionLineSegment()

static geom::CoordinateXY geos::algorithm::Intersection::intersectionLineSegment ( const geom::CoordinateXY &  line1, const geom::CoordinateXY &  line2, const geom::CoordinateXY &  seg1, const geom::CoordinateXY &  seg2  )

static

Computes the intersection point of a line and a line segment (if any). There will be no intersection point if:

• the segment does not intersect the line
• the line or the segment are degenerate (have zero length)

If the segment is collinear with the line the first segment endpoint is returned.

Parameters

line1	a point on the line
line2	a point on the line
seg1	an endpoint of the line segment
seg2	an endpoint of the line segment

Returns

the intersection point, or null if it is not possible to find an intersection

---

The documentation for this class was generated from the following file:

• Intersection.h