Polygon2D.cxx File Reference

#include "Polygon2D.h"

Go to the source code of this file.

Functions
float	FindSlope (const std::pair< float, float > &p1, const std::pair< float, float > &p2)
bool	Clockwise (double Ax, double Ay, double Bx, double By, double Cx, double Cy)
bool	SegmentOverlap (double Ax, double Ay, double Bx, double By, double Cx, double Cy, double Dx, double Dy)
std::pair< float, float >	GetIntersection (double Ax, double Ay, double Bx, double By, double Cx, double Cy, double Dx, double Dy)

Function Documentation

bool Clockwise	(	double	Ax,
		double	Ay,
		double	Bx,
		double	By,
		double	Cx,
		double	Cy
	)

Definition at line 12 of file Polygon2D.cxx.

Referenced by SegmentOverlap().

{
  return (Cy-Ay)*(Bx-Ax) > (By-Ay)*(Cx-Ax);
}

float FindSlope	(	const std::pair< float, float > &	p1,
		const std::pair< float, float > &	p2
	)

Definition at line 4 of file Polygon2D.cxx.

Referenced by Polygon2D::PolyOverlap().

{
  float slope = (p2.second-p1.second)/(p2.first-p1.first);
  return slope;
}

std::pair<float, float> GetIntersection	(	double	Ax,
		double	Ay,
		double	Bx,
		double	By,
		double	Cx,
		double	Cy,
		double	Dx,
		double	Dy
	)

Definition at line 28 of file Polygon2D.cxx.

References c1, and c2.

Referenced by lar_content::LArPointingClusterHelper::GetAverageDirection(), and Polygon2D::Polygon2D().

{

  //get equations for two lines
  // [Ax,Ay]<--->[Bx,By] : y = s1*x+c1
  // [Cx,Cy]<--->[Dx,Dy] : y = s2*x+c2
  double s1 = (By-Ay)/(Bx-Ax);
  double s2 = (Dy-Cy)/(Dx-Cx);
  double c1 = By-s1*Bx;
  double c2 = Dy-s2*Dx;

  double Xintersection = (c2-c1)/(s2-s1);
  double Yintersection = s1 * Xintersection + c1;
  std::pair<float,float> intersection;
  intersection = std::make_pair(Xintersection, Yintersection);

  return intersection;
}

bool SegmentOverlap	(	double	Ax,
		double	Ay,
		double	Bx,
		double	By,
		double	Cx,
		double	Cy,
		double	Dx,
		double	Dy
	)

Definition at line 18 of file Polygon2D.cxx.

References Clockwise().

Referenced by Polygon2D::PointInside(), Polygon2D::Polygon2D(), Polygon2D::PolyOverlapSegments(), and Polygon2D::UntanglePolygon().

{

  bool overlap = ( (Clockwise(Ax,Ay,Cx,Cy,Dx,Dy) != Clockwise(Bx,By,Cx,Cy,Dx,Dy))
                   and (Clockwise(Ax,Ay,Bx,By,Cx,Cy) != Clockwise(Ax,Ay,Bx,By,Dx,Dy)) );
  return overlap;
}