Jcg.geometry.kernel

Class ExactPredicates_2

java.lang.Object

Jcg.geometry.kernel.ExactPredicates_2

All Implemented Interfaces:

GeometricPredicates_2

public class ExactPredicates_2
extends java.lang.Object
implements GeometricPredicates_2

Exact geometric predicates for plane objects (points, segments, rays) Computations are performed with infinite precision arithmetic (using the java.util.BigDecimal class)

Version:

dec 2012

Author:

Luca Castelli Aleardi and Steve Oudot (INF562, Ecole Polytechnique)

Constructor Summary

Constructors

Constructor and Description
ExactPredicates_2()

Method Summary

Modifier and Type	Method and Description
boolean	collinear(Point_2 a, Point_2 b, Point_2 c) Returns true if a, b and c lie on a same line
boolean	doIntersect(Segment_2 s, Ray_2 r) Returns true if segment s and ray r intersect
boolean	doIntersect(Segment_2 s, Segment_2 t) Returns true if segments s and t intersect
boolean	inCircle(Point_2 p, Point_2 a, Point_2 b, Point_2 c) Tests if point p lies inside the circumcircle of triangle a,b,c
boolean	isCounterClockwise(Point_2 a, Point_2 b, Point_2 c) Returns true if a, b and c turn in counter-clockwise direction
boolean	liesOn(Point_2 p, Point_2 a, Point_2 b) Returns true if point p lies on segment ab
int	orientation(Point_2 a, Point_2 b, Point_2 c) Returns the orientation of a, b and c

Methods inherited from class java.lang.Object

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

Constructor Detail

ExactPredicates_2

public ExactPredicates_2()

Method Detail

orientation

public int orientation(Point_2 a,
                       Point_2 b,
                       Point_2 c)

Returns the orientation of a, b and c

Specified by:

orientation in interface GeometricPredicates_2

Parameters:

a,b,c - the 3 points to test

Returns:

1 if sequence (a, b, c) turns in counter-clockwise direction, -1 if it turns in clockwise direction, 0 if the points are collinear

isCounterClockwise

public boolean isCounterClockwise(Point_2 a,
                                  Point_2 b,
                                  Point_2 c)

Returns true if a, b and c turn in counter-clockwise direction

Specified by:

isCounterClockwise in interface GeometricPredicates_2

Parameters:

a,b,c - the 3 points to test

Returns:

true if a, b and c turn in counter-clockwise direction

collinear

public boolean collinear(Point_2 a,
                         Point_2 b,
                         Point_2 c)

Returns true if a, b and c lie on a same line

Specified by:

collinear in interface GeometricPredicates_2

Parameters:

a,b,c - the 3 points to test

Returns:

true if a, b and c are collinear (lie on a same line) Test is filtered: if precision bound epsilon is reached, then perform computation with infinite precision arithmetic (using the java.util.BigDecimal class)

inCircle

public boolean inCircle(Point_2 p,
                        Point_2 a,
                        Point_2 b,
                        Point_2 c)

Tests if point p lies inside the circumcircle of triangle a,b,c

Specified by:

inCircle in interface GeometricPredicates_2

Parameters:

a,b,c - triangle

p - point to test

Returns:

true/false

doIntersect

public boolean doIntersect(Segment_2 s,
                           Segment_2 t)

Returns true if segments s and t intersect

Specified by:

doIntersect in interface GeometricPredicates_2

Parameters:

s,t - the 2 segments

Returns:

true if s,t intersect each other

doIntersect

public boolean doIntersect(Segment_2 s,
                           Ray_2 r)

Returns true if segment s and ray r intersect

Specified by:

doIntersect in interface GeometricPredicates_2

Parameters:

s - the segment

r - the ray

Returns:

true if s intersects r Warning: test is not exact.

liesOn

public boolean liesOn(Point_2 p,
                      Point_2 a,
                      Point_2 b)

Returns true if point p lies on segment ab

Specified by:

liesOn in interface GeometricPredicates_2

Parameters:

a,b,p - the 3 points

Returns:

true if ab contains point p