Jcg.geometry.kernel

Interface GeometricPredicates_2

All Known Implementing Classes:

ApproximatePredicates_2, ExactPredicates_2, FilteredPredicates_2

public interface GeometricPredicates_2

Interface defining geometric predicates for plane objects (points, segments, rays)

Version:

dec 2012

Author:

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

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

Method Detail

orientation

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

Returns the orientation of a, b and c

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

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

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

Parameters:

a,b,c - the 3 points to test

Returns:

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

collinear

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

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

Parameters:

a,b,c - the 3 points to test

Returns:

true if a, b and c are collinear (lie on a same line)

inCircle

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

Parameters:

a,b,c - triangle

p - point to test

Returns:

true/false

doIntersect

boolean doIntersect(Segment_2 s,
                    Segment_2 t)

Returns true if segments s and t intersect

Parameters:

s,t - the 2 segments

Returns:

true if s,t intersect each other

doIntersect

boolean doIntersect(Segment_2 s,
                    Ray_2 r)

Returns true if segment s and ray r intersect

Parameters:

s - the segment

r - the ray

Returns:

true if s intersects r

liesOn

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

Returns true if point p lies on segment ab

Parameters:

a,b,p - the 3 points

Returns:

true if ab contains point p