ExtCylSurfaceTarget Class Reference

Defines a closed cylinder for the geant4e "target", the surface that encloses the volume within which track extrapolation is done. More...

#include <ExtCylSurfaceTarget.h>

Inheritance diagram for ExtCylSurfaceTarget:

Public Member Functions
	ExtCylSurfaceTarget (const G4double &, const G4double &, const G4double &)
	Construct the closed cylindrical surface No coordinate transformations allowed: cylinder is coaxial with z axis.
	~ExtCylSurfaceTarget ()
	Destructor.
virtual G4ThreeVector	IntersectLocal (const G4ThreeVector &point, const G4ThreeVector &direc) const
	Return the intersection of the cylinder with the line defined in local (cylinder) coordinates by point and direc.
virtual G4double	GetDistanceFromPoint (const G4ThreeVector &point, const G4ThreeVector &direc) const
	Get the distance from a point to the cylinder along direc.
virtual G4double	GetDistanceFromPoint (const G4ThreeVector &point) const
	Get the shortest distance from a point to the cylinder.
virtual G4Plane3D	GetTangentPlane (const G4ThreeVector &point) const
	Get the plane tangent to the cylinder at a given point.
virtual void	Dump (const G4String &msg) const
	Dump the cylinder parameters.

Private Attributes
G4double	m_radius
	Cylinder radius.
G4double	m_zmin
	Cylinder minimum-z coordinate.
G4double	m_zmax
	Cylinder maximum-z coordinate.
G4double	m_tolerance
	Tolerance for distance between a point and cylinder's curved surface.

Detailed Description

Defines a closed cylinder for the geant4e "target", the surface that encloses the volume within which track extrapolation is done.

Definition at line 28 of file ExtCylSurfaceTarget.h.

Constructor & Destructor Documentation

ExtCylSurfaceTarget()

ExtCylSurfaceTarget	(	const G4double &	radius,
		const G4double &	zmin,
		const G4double &	zmax
	)

Construct the closed cylindrical surface No coordinate transformations allowed: cylinder is coaxial with z axis.

Definition at line 20 of file ExtCylSurfaceTarget.cc.

                                                               :
  m_radius(radius),
  m_zmin(zmin),
  m_zmax(zmax),
  m_tolerance(1000.0 * G4GeometryTolerance::GetInstance()->GetSurfaceTolerance())
{
  theType = G4ErrorTarget_CylindricalSurface;
  B2DEBUG(1, "Simulation::ExtCylSurfaceTarget created with radius "
          << m_radius << " zmin " << zmin << " zmax " << zmax);
}

~ExtCylSurfaceTarget()

~ExtCylSurfaceTarget

(

)

Destructor.

Definition at line 33 of file ExtCylSurfaceTarget.cc.

{
}

Member Function Documentation

Dump()

void Dump ( const G4String &  msg ) const

virtual

Dump the cylinder parameters.

Dump the cylinder parameters: EMPTY STUB

Definition at line 120 of file ExtCylSurfaceTarget.cc.

{
}

GetDistanceFromPoint() [1/2]

G4double GetDistanceFromPoint ( const G4ThreeVector &  point ) const

virtual

Get the shortest distance from a point to the cylinder.

Definition at line 62 of file ExtCylSurfaceTarget.cc.

{
 
  G4double dist = m_radius - point.perp();
  dist = fmin(dist, point.z() - m_zmin);
  dist = fmin(dist, m_zmax - point.z());
 
  B2DEBUG(300, "Simulation::ExtCylSurfaceTarget::GetDistanceFromPoint():  Global point "
          << point << " minimum distance " << dist);
 
  return dist;
}

GetDistanceFromPoint() [2/2]

G4double GetDistanceFromPoint ( const G4ThreeVector &  point, const G4ThreeVector &  direc  ) const

virtual

Get the distance from a point to the cylinder along direc.

Definition at line 37 of file ExtCylSurfaceTarget.cc.

{
  if (fabs(dir.mag() - 1.0) > 1.0E-10) {
    B2FATAL("Simulation::ExtCylSurfaceTarget::GetDistanceFromPoint() direction is not a unit vector: " << dir);
  }
 
  // Get distance to intersection point with the cylinder's curved surface
  // should be negative if outside!  G4double dist = (point - IntersectLocal(point, dir)).mag();
  G4double dist = (IntersectLocal(point, dir) - point) * dir;
 
  // Get intersection point with the plane at either zmin or zmax
  G4double dirz = dir.z();
  if (dirz < -1.0E-10) {
    dist = fmin(dist, (m_zmin - point.z()) / dirz);
  } else if (dirz > 1.0E-10) {
    dist = fmin(dist, (m_zmax - point.z()) / dirz);
  }
 
  B2DEBUG(300, "Simulation::ExtCylSurfaceTarget::GetDistanceFromPoint():  Global point "
          << point << " dir " << dir << " distance " << dist);
 
  return dist;
}

GetTangentPlane()

G4Plane3D GetTangentPlane ( const G4ThreeVector &  point ) const

virtual

Get the plane tangent to the cylinder at a given point.

Definition at line 106 of file ExtCylSurfaceTarget.cc.

{
  // check that point is at the cylinder's curved surface
  if (fabs(point.perp() - m_radius) > m_tolerance) {
    B2ERROR("Simulation::ExtCylSurfaceTarget::GetTangentPlane(): point "
            << point << " is not at surface; radial distance is " << point.perp() - m_radius);
  }
 
  G4Normal3D normal(point);
 
  return G4Plane3D(normal, point);
}

IntersectLocal()

G4ThreeVector IntersectLocal ( const G4ThreeVector &  point, const G4ThreeVector &  direc  ) const

virtual

Return the intersection of the cylinder with the line defined in local (cylinder) coordinates by point and direc.

Definition at line 75 of file ExtCylSurfaceTarget.cc.

{
  // localDir has already been verified to be a unit vector
  G4double eqa = localDir.x() * localDir.x() + localDir.y() * localDir.y();
  G4double eqb = 2.0 * (localPoint.x() * localDir.x() + localPoint.y() * localDir.y());
  G4double eqc = localPoint.x() * localPoint.x() + localPoint.y() * localPoint.y()
                 - m_radius * m_radius;
  G4double eqaInside = (localPoint.perp() > m_radius) ? -eqa : eqa;
 
  G4ThreeVector intersection = localPoint;
  if (eqaInside > 0.0) {
    intersection += localDir * ((-eqb + sqrt(eqb * eqb - 4.0 * eqa * eqc)) / (2.0 * eqa));
  } else if (eqaInside < 0.0) {
    intersection += localDir * ((-eqb - sqrt(eqb * eqb - 4.0 * eqa * eqc)) / (2.0 * eqa));
  } else {
    if (eqb != 0.0) {
      intersection -= localDir * (eqc / eqb);
    } else {
      B2WARNING("Simulation::ExtCylSurfaceTarget::IntersectLocal():  localPoint "
                << localPoint << " localDir " << localDir << " does not intersect with cylinder");
      intersection = localDir * kInfinity;
    }
  }
 
  B2DEBUG(300, "Simulation::ExtCylSurfaceTarget::IntersectLocal(): localPoint "
          << localPoint << " localDir " << localDir << " radial intersection " << intersection.perp());
 
  return intersection;
}

Member Data Documentation

m_radius

G4double m_radius

private

Cylinder radius.

Definition at line 60 of file ExtCylSurfaceTarget.h.

m_tolerance

G4double m_tolerance

private

Tolerance for distance between a point and cylinder's curved surface.

Definition at line 69 of file ExtCylSurfaceTarget.h.

m_zmax

G4double m_zmax

private

Cylinder maximum-z coordinate.

Definition at line 66 of file ExtCylSurfaceTarget.h.

m_zmin

G4double m_zmin

private

Cylinder minimum-z coordinate.

Definition at line 63 of file ExtCylSurfaceTarget.h.

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The documentation for this class was generated from the following files:

• simulation/kernel/include/ExtCylSurfaceTarget.h
• simulation/kernel/src/ExtCylSurfaceTarget.cc