GEOS  3.9.0dev
geos::geom::TrianglePredicate Class Reference

Algorithms for computing values and predicates associated with triangles. More...

`#include <TrianglePredicate.h>`

## Static Public Member Functions

static bool isInCircleNonRobust (const Coordinate &a, const Coordinate &b, const Coordinate &c, const Coordinate &p)

static bool isInCircleNormalized (const Coordinate &a, const Coordinate &b, const Coordinate &c, const Coordinate &p)

static bool isInCircleRobust (const Coordinate &a, const Coordinate &b, const Coordinate &c, const Coordinate &p)

## Detailed Description

Algorithms for computing values and predicates associated with triangles.

For some algorithms extended-precision implementations are provided, which are more robust (i.e. they produce correct answers in more cases). Also, some more robust formulations of some algorithms are provided, which utilize normalization to the origin.

## Member Function Documentation

 static bool geos::geom::TrianglePredicate::isInCircleNonRobust ( const Coordinate & a, const Coordinate & b, const Coordinate & c, const Coordinate & p )
static

Tests if a point is inside the circle defined by the triangle with vertices a, b, c (oriented counter-clockwise). This test uses simple double-precision arithmetic, and thus may not be robust.

Parameters
 a a vertex of the triangle b a vertex of the triangle c a vertex of the triangle p the point to test
Returns
true if this point is inside the circle defined by the points a, b, c
 static bool geos::geom::TrianglePredicate::isInCircleNormalized ( const Coordinate & a, const Coordinate & b, const Coordinate & c, const Coordinate & p )
static

Tests if a point is inside the circle defined by the triangle with vertices a, b, c (oriented counter-clockwise). This test uses simple double-precision arithmetic, and thus is not 10% robust. However, by using normalization to the origin it provides improved robustness and increased performance.

Based on code by J.R.Shewchuk.

Parameters
 a a vertex of the triangle b a vertex of the triangle c a vertex of the triangle p the point to test
Returns
true if this point is inside the circle defined by the points a, b, c
 static bool geos::geom::TrianglePredicate::isInCircleRobust ( const Coordinate & a, const Coordinate & b, const Coordinate & c, const Coordinate & p )
static

Tests if a point is inside the circle defined by the triangle with vertices a, b, c (oriented counter-clockwise). This method uses more robust computation.

Parameters
 a a vertex of the triangle b a vertex of the triangle c a vertex of the triangle p the point to test
Returns
true if this point is inside the circle defined by the points a, b, c