org.locationtech.jts.algorithm

Class CGAlgorithmsDD

java.lang.Object

org.locationtech.jts.algorithm.CGAlgorithmsDD

public class CGAlgorithmsDD
extends Object

Implements basic computational geometry algorithms using DD arithmetic.

Author:

Martin Davis

Method Summary

Modifier and Type	Method and Description
static Coordinate	intersection(Coordinate p1, Coordinate p2, Coordinate q1, Coordinate q2) Computes an intersection point between two lines using DD arithmetic.
static int	orientationIndex(Coordinate p1, Coordinate p2, Coordinate q) Returns the index of the direction of the point q relative to a vector specified by p1-p2.
static int	orientationIndex(double p1x, double p1y, double p2x, double p2y, double qx, double qy) Returns the index of the direction of the point q relative to a vector specified by p1-p2.
static int	signOfDet2x2(DD x1, DD y1, DD x2, DD y2) Computes the sign of the determinant of the 2x2 matrix with the given entries.
static int	signOfDet2x2(double dx1, double dy1, double dx2, double dy2) Computes the sign of the determinant of the 2x2 matrix with the given entries.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

orientationIndex

public static int orientationIndex(Coordinate p1,
                                   Coordinate p2,
                                   Coordinate q)

Returns the index of the direction of the point q relative to a vector specified by p1-p2.

Parameters:

p1 - the origin point of the vector

p2 - the final point of the vector

q - the point to compute the direction to

Returns:

1 if q is counter-clockwise (left) from p1-p2 -1 if q is clockwise (right) from p1-p2 0 if q is collinear with p1-p2

orientationIndex

public static int orientationIndex(double p1x,
                                   double p1y,
                                   double p2x,
                                   double p2y,
                                   double qx,
                                   double qy)

Returns the index of the direction of the point q relative to a vector specified by p1-p2.

Parameters:

p1x - the x ordinate of the vector origin point

p1y - the y ordinate of the vector origin point

p2x - the x ordinate of the vector final point

p2y - the y ordinate of the vector final point

qx - the x ordinate of the query point

qy - the y ordinate of the query point

Returns:

1 if q is counter-clockwise (left) from p1-p2 -1 if q is clockwise (right) from p1-p2 0 if q is collinear with p1-p2

signOfDet2x2

public static int signOfDet2x2(DD x1,
                               DD y1,
                               DD x2,
                               DD y2)

Computes the sign of the determinant of the 2x2 matrix with the given entries.

Returns:

-1 if the determinant is negative, 1 if the determinant is positive, 0 if the determinant is 0.

signOfDet2x2

public static int signOfDet2x2(double dx1,
                               double dy1,
                               double dx2,
                               double dy2)

Computes the sign of the determinant of the 2x2 matrix with the given entries.

Returns:

-1 if the determinant is negative, 1 if the determinant is positive, 0 if the determinant is 0.

intersection

public static Coordinate intersection(Coordinate p1,
                                      Coordinate p2,
                                      Coordinate q1,
                                      Coordinate q2)

Computes an intersection point between two lines using DD arithmetic. If the lines are parallel (either identical or separate) a null value is returned.

Parameters:

p1 - an endpoint of line segment 1

p2 - an endpoint of line segment 1

q1 - an endpoint of line segment 2

q2 - an endpoint of line segment 2

Returns:

an intersection point if one exists, or null if the lines are parallel