Gabriele Cosmo
143 lines
6.1 KiB
C++
143 lines
6.1 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// INCL++ intra-nuclear cascade model
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// Alain Boudard, CEA-Saclay, France
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// Joseph Cugnon, University of Liege, Belgium
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// Jean-Christophe David, CEA-Saclay, France
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// Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
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// Sylvie Leray, CEA-Saclay, France
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// Davide Mancusi, CEA-Saclay, France
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//
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#define INCLXX_IN_GEANT4_MODE 1
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#include "globals.hh"
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/** \file G4INCLIntersection.hh
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* \brief Simple class for computing intersections between a straight line and a sphere.
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*
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* \date 12 December 2011
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* \author Davide Mancusi
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*/
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#ifndef G4INCLINTERSECTION_HH
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#define G4INCLINTERSECTION_HH 1
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#include "G4INCLThreeVector.hh"
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#include <utility>
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namespace G4INCL {
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/** \brief Intersection-point structure
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*
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* The structure contains the time and position of the intersection point
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* of a trajectory with a surface, if it exists.
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*/
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struct Intersection {
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Intersection(const G4bool e, const G4double t, const ThreeVector &p) :
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exists(e), time(t), position(p) {}
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G4bool exists;
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G4double time;
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ThreeVector position;
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};
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namespace IntersectionFactory {
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/** \brief Compute the first intersection of a straight particle
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* trajectory with a sphere.
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*
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* \param x0 the starting position of the trajectory
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* \param p the trajectory direction
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* \param r the radius of the sphere (centred in the origin)
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* \return an Intersection. The G4bool is true if an intersection exists,
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* in which case its position is stored in the ThreeVector and
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* its time in the G4double.
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*/
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Intersection getEarlierTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &p, const G4double r);
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/** \brief Compute the second intersection of a straight particle
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* trajectory with a sphere.
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*
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* \param x0 the starting position of the trajectory
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* \param p the trajectory direction
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* \param r the radius of the sphere (centred in the origin)
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* \return an Intersection. The G4bool is true if an intersection exists,
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* in which case its position is stored in the ThreeVector and
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* its time in the G4double.
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*/
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Intersection getLaterTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &p, const G4double r);
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/** \brief Compute both intersections of a straight particle
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* trajectory with a sphere.
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*
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* \param x0 the starting position of the trajectory
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* \param p the trajectory direction
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* \param r the radius of the sphere (centred in the origin)
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* \return an Intersection. The G4bool is true if an intersection exists,
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* in which case its position is stored in the ThreeVector and
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* its time in the G4double.
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*/
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std::pair<Intersection,Intersection> getTrajectoryIntersections(const ThreeVector &x0, const ThreeVector &p, const G4double r);
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namespace {
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Intersection getTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &v, const G4double r, const G4bool earliest) {
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const G4double scalarVelocity = v.mag();
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ThreeVector velocityUnitVector = v / scalarVelocity;
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ThreeVector positionTransverse = x0 - velocityUnitVector * x0.dot(velocityUnitVector);
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const G4double impactParameter = positionTransverse.mag();
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const G4double r2 = r*r;
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G4double distanceZ2 = r2 - impactParameter * impactParameter;
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if(distanceZ2 < 0.0)
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return Intersection(false, 0.0, ThreeVector());
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const G4double distanceZ = std::sqrt(distanceZ2);
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const ThreeVector position = positionTransverse + velocityUnitVector * (earliest ? -distanceZ : distanceZ);
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const G4double time = (position-x0).dot(velocityUnitVector)/scalarVelocity;
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return Intersection(true, time, position);
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}
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}
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inline Intersection getEarlierTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &p, const G4double r) {
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return getTrajectoryIntersection(x0, p, r, true);
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}
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inline Intersection getLaterTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &p, const G4double r) {
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return getTrajectoryIntersection(x0, p, r, false);
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}
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inline std::pair<Intersection,Intersection> getTrajectoryIntersections(const ThreeVector &x0, const ThreeVector &p, const G4double r) {
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return std::make_pair(
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getTrajectoryIntersection(x0, p, r, true),
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getTrajectoryIntersection(x0, p, r, false)
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);
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}
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}
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}
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#endif /* G4INCLINTERSECTION_HH */
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