#include <HelixBarrelPlaneCrossing2OrderLocal.h>

Public Types
typedef Surface::GlobalPoint	GlobalPoint
typedef Surface::GlobalVector	GlobalVector
typedef Surface::LocalPoint	LocalPoint
typedef Surface::LocalVector	LocalVector
Public Member Functions
LocalVector	direction () const
	HelixBarrelPlaneCrossing2OrderLocal (const GlobalPoint &startingPos, const GlobalVector &startingDir, double rho, const Plane &plane)
	HelixBarrelPlaneCrossing2OrderLocal ()
LocalPoint	position () const
Private Types
typedef Basic2DVector< float >	Vector2D
Private Attributes
LocalVector	theDir
LocalPoint	thePos

Detailed Description

Calculates an approximate crossing of a helix and a barrel plane. The helix circle is approximated with a parabola. The current class name is misleading, since it does not have the HelixPlaneCrossing interface.

Definition at line 12 of file HelixBarrelPlaneCrossing2OrderLocal.h.

Member Typedef Documentation

typedef Surface::GlobalPoint HelixBarrelPlaneCrossing2OrderLocal::GlobalPoint

Definition at line 15 of file HelixBarrelPlaneCrossing2OrderLocal.h.

typedef Surface::GlobalVector HelixBarrelPlaneCrossing2OrderLocal::GlobalVector

Definition at line 16 of file HelixBarrelPlaneCrossing2OrderLocal.h.

typedef Surface::LocalPoint HelixBarrelPlaneCrossing2OrderLocal::LocalPoint

Definition at line 17 of file HelixBarrelPlaneCrossing2OrderLocal.h.

typedef Surface::LocalVector HelixBarrelPlaneCrossing2OrderLocal::LocalVector

Definition at line 18 of file HelixBarrelPlaneCrossing2OrderLocal.h.

typedef Basic2DVector<float> HelixBarrelPlaneCrossing2OrderLocal::Vector2D [private]

Definition at line 32 of file HelixBarrelPlaneCrossing2OrderLocal.h.

Constructor & Destructor Documentation

HelixBarrelPlaneCrossing2OrderLocal::HelixBarrelPlaneCrossing2OrderLocal ( ) [inline]

Definition at line 20 of file HelixBarrelPlaneCrossing2OrderLocal.h.

{}

HelixBarrelPlaneCrossing2OrderLocal::HelixBarrelPlaneCrossing2OrderLocal	(	const GlobalPoint &	startingPos,
		const GlobalVector &	startingDir,
		double	rho,
		const Plane &	plane
	)

Definition at line 6 of file HelixBarrelPlaneCrossing2OrderLocal.cc.

References diffTreeTool::diff, dir, f, PV3DBase< T, PVType, FrameType >::mag2(), pos, theDir, thePos, GloballyPositioned< T >::toLocal(), PV3DBase< T, PVType, FrameType >::x(), Basic2DVector< T >::x(), x, PV3DBase< T, PVType, FrameType >::y(), Basic2DVector< T >::y(), detailsBasic3DVector::y, and PV3DBase< T, PVType, FrameType >::z().

{
  // translate problem to local frame of the plane
  LocalPoint lPos = plane.toLocal(startingPos);
  LocalVector lDir = plane.toLocal(startingDir);

  // check if local frame is already special (local Y axis == global Z axis)
  LocalVector yPrime = plane.toLocal( GlobalVector(0,0,1.f));
  LocalVector diff = yPrime - LocalVector(0,-1.f,0);
  float sinPhi=0, cosPhi=0;
  bool rotated;
  Vector2D pos;
  Vector2D dir;

  if (diff.mag2() < 1.e-10) {

    // cout << "Plane already oriented, yPrime = " << yPrime << endl;

    // we are already in the special orientation
    pos = Vector2D( lPos.x(), lPos.y());
    dir = Vector2D( lDir.x(), lDir.y());;
    rotated = false;
  }
  else {

    // cout << "Plane needs rotation, yPrime = " << yPrime << endl;

    // we need to rotate the problem 
    sinPhi = yPrime.y();
    cosPhi = yPrime.x();
    pos = Vector2D( lPos.x()*cosPhi + lPos.y()*sinPhi,
                    -lPos.x()*sinPhi + lPos.y()*cosPhi);
    dir = Vector2D( lDir.x()*cosPhi + lDir.y()*sinPhi,
                    -lDir.x()*sinPhi + lDir.y()*cosPhi);
    rotated = true;
  }

  double d = -lPos.z();
  double x = pos.x() + dir.x()/lDir.z()*d - 0.5*rho*d*d;
  double y = pos.y() + dir.y()/lDir.z()*d;

//    cout << "d= " << d << ", pos.x()= " << pos.x() 
//         << ", dir.x()/lDir.z()= " << dir.x()/lDir.z() 
//         << ", 0.5*rho*d*d= " << 0.5*rho*d*d << endl;

  if (!rotated) {
    thePos = LocalPoint( x, y, 0);
    theDir = LocalVector( dir.x()+rho*d, dir.y(), lDir.z());
  }
  else {
    thePos = LocalPoint( x*cosPhi - y*sinPhi,
                         x*sinPhi + y*cosPhi, 0);
    float px = dir.x()+rho*d;
    theDir = LocalVector( px*cosPhi - dir.y()*sinPhi,
                          px*sinPhi + dir.y()*cosPhi, lDir.z());
  }
}