You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
106 lines
3.2 KiB
C++
106 lines
3.2 KiB
C++
/**********************************************************************
|
|
*
|
|
* GEOS - Geometry Engine Open Source
|
|
* http://geos.osgeo.org
|
|
*
|
|
* Copyright (C) 2006 Refractions Research Inc.
|
|
*
|
|
* This is free software; you can redistribute and/or modify it under
|
|
* the terms of the GNU Lesser General Public Licence as published
|
|
* by the Free Software Foundation.
|
|
* See the COPYING file for more information.
|
|
*
|
|
**********************************************************************/
|
|
|
|
#ifndef GEOS_GEOM_TRIANGLE_H
|
|
#define GEOS_GEOM_TRIANGLE_H
|
|
|
|
#include <geos/export.h>
|
|
#include <geos/geom/Coordinate.h>
|
|
|
|
#include <geos/inline.h>
|
|
|
|
namespace geos {
|
|
namespace geom { // geos::geom
|
|
|
|
/**
|
|
* \brief
|
|
* Represents a planar triangle, and provides methods for calculating various
|
|
* properties of triangles.
|
|
*/
|
|
class GEOS_DLL Triangle {
|
|
public:
|
|
Coordinate p0, p1, p2;
|
|
|
|
Triangle(const Coordinate& nP0, const Coordinate& nP1, const Coordinate& nP2)
|
|
:
|
|
p0(nP0),
|
|
p1(nP1),
|
|
p2(nP2)
|
|
{}
|
|
|
|
/** \brief
|
|
* The inCentre of a triangle is the point which is equidistant
|
|
* from the sides of the triangle.
|
|
*
|
|
* This is also the point at which the bisectors of the angles meet.
|
|
*
|
|
* @param resultPoint the point into which to write the inCentre of the triangle
|
|
*/
|
|
void inCentre(Coordinate& resultPoint);
|
|
|
|
/** \brief
|
|
* Computes the circumcentre of a triangle.
|
|
*
|
|
* The circumcentre is the centre of the circumcircle, the smallest circle
|
|
* which encloses the triangle. It is also the common intersection point of
|
|
* the perpendicular bisectors of the sides of the triangle, and is the only
|
|
* point which has equal distance to all three vertices of the triangle.
|
|
*
|
|
* The circumcentre does not necessarily lie within the triangle. For example,
|
|
* the circumcentre of an obtuse isoceles triangle lies outside the triangle.
|
|
*
|
|
* This method uses an algorithm due to J.R.Shewchuk which uses normalization
|
|
* to the origin to improve the accuracy of computation. (See *Lecture Notes
|
|
* on Geometric Robustness*, Jonathan Richard Shewchuk, 1999).
|
|
*
|
|
* @param resultPoint the point into which to write the inCentre of the triangle
|
|
*/
|
|
void circumcentre(Coordinate& resultPoint);
|
|
void circumcentreDD(Coordinate& resultPoint);
|
|
|
|
bool isIsoceles();
|
|
|
|
/// Computes the circumcentre of a triangle.
|
|
static const Coordinate circumcentre(const Coordinate& p0, const Coordinate& p1, const Coordinate& p2);
|
|
|
|
private:
|
|
|
|
/**
|
|
* Computes the determinant of a 2x2 matrix. Uses standard double-precision
|
|
* arithmetic, so is susceptible to round-off error.
|
|
*
|
|
* @param m00
|
|
* the [0,0] entry of the matrix
|
|
* @param m01
|
|
* the [0,1] entry of the matrix
|
|
* @param m10
|
|
* the [1,0] entry of the matrix
|
|
* @param m11
|
|
* the [1,1] entry of the matrix
|
|
* @return the determinant
|
|
*/
|
|
double det(double m00, double m01, double m10, double m11) const;
|
|
|
|
};
|
|
|
|
|
|
} // namespace geos::geom
|
|
} // namespace geos
|
|
|
|
//#ifdef GEOS_INLINE
|
|
//# include "geos/geom/Triangle.inl"
|
|
//#endif
|
|
|
|
#endif // ndef GEOS_GEOM_TRIANGLE_H
|