StraightLineBarrelCylinderCrossing Class Reference

#include <StraightLineBarrelCylinderCrossing.h>

Public Member Functions
std::pair< bool, double >	pathLength (const Cylinder &cyl) const
GlobalPoint	position (const double s) const
	StraightLineBarrelCylinderCrossing (const GlobalPoint &startingPos, const GlobalVector &startingDir, const PropagationDirection propDir)

Private Types
typedef GlobalVector	DirectionType
typedef Basic2DVector< float >	DirectionType2D
typedef GlobalPoint	PositionType
typedef Basic2DVector< float >	PositionType2D

Private Member Functions
std::pair< bool, double >	chooseSolution (const double s1, const double s2) const
	Chooses the right solution w.r.t. the propagation direction. More...

Private Attributes
const DirectionType	theP0
const PropagationDirection	thePropDir
const PositionType	theX0

Detailed Description

Calculates the intersection of a straight line with a barrel cylinder.

Definition at line 17 of file StraightLineBarrelCylinderCrossing.h.

Member Typedef Documentation

typedef GlobalVector StraightLineBarrelCylinderCrossing::DirectionType

private

Definition at line 48 of file StraightLineBarrelCylinderCrossing.h.

typedef Basic2DVector<float> StraightLineBarrelCylinderCrossing::DirectionType2D

private

Definition at line 50 of file StraightLineBarrelCylinderCrossing.h.

typedef GlobalPoint StraightLineBarrelCylinderCrossing::PositionType

private

Definition at line 47 of file StraightLineBarrelCylinderCrossing.h.

typedef Basic2DVector<float> StraightLineBarrelCylinderCrossing::PositionType2D

private

Definition at line 49 of file StraightLineBarrelCylinderCrossing.h.

Constructor & Destructor Documentation

StraightLineBarrelCylinderCrossing::StraightLineBarrelCylinderCrossing	(	const GlobalPoint &	startingPos,
		const GlobalVector &	startingDir,
		const PropagationDirection	propDir
	)

Constructor uses global frame (barrel cylinders are by definition in global co-ordinates)

Definition at line 8 of file StraightLineBarrelCylinderCrossing.cc.

                                     :
  theX0(startingPos),
  theP0(startingDir.unit()),
  thePropDir(propDir) {}

Member Function Documentation

std::pair< bool, double > StraightLineBarrelCylinderCrossing::chooseSolution ( const double  s1, const double  s2  ) const

private

Chooses the right solution w.r.t. the propagation direction.

Definition at line 39 of file StraightLineBarrelCylinderCrossing.cc.

References alongMomentum, anyDirection, indexGen::s2, and thePropDir.

Referenced by pathLength().

{
  //
  // follows the logic implemented in HelixBarrelCylinderCrossing
  //
  if ( thePropDir==anyDirection ) {
    return std::pair<bool,double>(true,(fabs(s1)<fabs(s2)?s1:s2));
  }
  else {
    int propSign = thePropDir==alongMomentum ? 1 : -1;
    if ( s1*s2 < 0) {
      // if different signs return the positive one
      return std::pair<bool,double>(true,((s1*propSign>0)?s1:s2));
    }
    else if ( s1*propSign>0 ) {
      // if both positive, return the shortest
      return std::pair<bool,double>(true,(fabs(s1)<fabs(s2)?s1:s2));
    }
  }
  return std::pair<bool,double>(false,0.);
}

std::pair< bool, double > StraightLineBarrelCylinderCrossing::pathLength

(

const Cylinder &

cyl

)

const

Propagation status (true if valid) and (signed) path length along the line from the starting point to the cylinder.

Definition at line 15 of file StraightLineBarrelCylinderCrossing.cc.

References chooseSolution(), prop_logic::eq(), dttmaxenums::R, Cylinder::radius(), theP0, theX0, Surface::toGlobal(), PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

Referenced by RKPropagatorInS::propagateParametersOnCylinder().

{
  //
  // radius of cylinder and transversal position relative to axis
  //
  double R(cylinder.radius());
  GlobalPoint axis(cylinder.toGlobal(Cylinder::LocalPoint(0.,0.)));
  PositionType2D xt2d(theX0.x()-axis.x(),theX0.y()-axis.y());
  //
  // transverse direction
  // 
  DirectionType2D pt2d(theP0.x(),theP0.y());
  //
  // solution of quadratic equation for s - assume |theP0|=1
  //
  RealQuadEquation eq(pt2d.mag2(),2.*xt2d.dot(pt2d),xt2d.mag2()-R*R);
  if ( !eq.hasSolution )  return std::pair<bool,double>(false,0.);
  //
  // choice of solution and verification of direction
  //
  return chooseSolution(eq.first,eq.second);
}

GlobalPoint StraightLineBarrelCylinderCrossing::position ( const double  s ) const

inline

Returns the position along the line that corresponds to path length "s" from the starting point. If s is obtained from the pathLength method the position is the intersection point with the cylinder.

Definition at line 37 of file StraightLineBarrelCylinderCrossing.h.

References theP0, and theX0.

Referenced by RKPropagatorInS::propagateParametersOnCylinder().

{ return GlobalPoint(theX0+s*theP0);}

Member Data Documentation

const DirectionType StraightLineBarrelCylinderCrossing::theP0

private

Definition at line 53 of file StraightLineBarrelCylinderCrossing.h.

Referenced by pathLength(), and position().

const PropagationDirection StraightLineBarrelCylinderCrossing::thePropDir

private

Definition at line 54 of file StraightLineBarrelCylinderCrossing.h.

Referenced by chooseSolution().

const PositionType StraightLineBarrelCylinderCrossing::theX0

private

Definition at line 52 of file StraightLineBarrelCylinderCrossing.h.

Referenced by pathLength(), and position().