Gabriele Cosmo
93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
// This code implementation is the intellectual property of
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// the GEANT4 collaboration.
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//
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// By copying, distributing or modifying the Program (or any work
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// based on the Program) you indicate your acceptance of this statement,
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// and all its terms.
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//
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// $Id: G4Parabola.cc,v 1.1.10.1 1999/12/07 20:48:25 gunter Exp $
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// GEANT4 tag $Name: geant4-01-00 $
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//
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#include "G4Parabola.hh"
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G4Parabola::G4Parabola(){}
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G4Parabola::~G4Parabola(){}
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G4Curve* G4Parabola::Project(const G4Transform3D& tr)
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{
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G4double axisZ= (tr*position.GetPZ()).unit().z();
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if (abs(axisZ)<kAngTolerance)
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return 0;
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G4Vector3D newAxis(0, 0, axisZ>0? +1: -1);
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G4Vector3D xPrime= tr*position.GetPX();
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xPrime.setZ(0);
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G4Vector3D yPrime= tr*position.GetPY();
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yPrime.setZ(0);
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G4double u= -(xPrime*yPrime)/xPrime.mag2();
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G4Point3D newLocation= tr*position.GetLocation()+
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focalDist*(u*u*xPrime+2*u*yPrime);
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newLocation.setZ(0);
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G4Vector3D newRefDirection= xPrime;
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G4double newFocalDist= (focalDist*((2*u+1)*xPrime+2*yPrime)).mag()/sqrt(5.);
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// create the new parabola
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G4Axis2Placement3D newPosition;
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newPosition.Init(newRefDirection, newAxis, newLocation);
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G4Parabola* r= new G4Parabola;
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r->Init(newPosition, newFocalDist);
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// introduce the shift in the parametrization
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// maybe the Sign must be changed?
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r->SetPShift(u);
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// set the bounds when necessary
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if (IsBounded())
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r->SetBounds(GetPStart(), GetPEnd());
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return r;
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}
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void G4Parabola::InitBounded()
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{
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// the bbox must include the start and endpoints as well as the
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// extreme points if they lie on the curve
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bBox.Init(GetStart(), GetEnd());
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// the parameter values
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// belonging to the points with an extreme x, y and z coordinate
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for (G4int i=0; i<3; i++)
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{
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G4double x_i= position.GetPX()(i);
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if (abs(x_i) <= kAngTolerance)
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{
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G4double u= - position.GetPY()(i) / x_i;
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if (IsPOn(u))
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bBox.Extend(GetPoint(u));
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}
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}
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}
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G4bool G4Parabola::Tangent(G4CurvePoint& cp, G4Vector3D& v)
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{
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// The tangent is computed from the 3D point representation
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// for all conics. An alternaive implementation (based on
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// the parametric point) might be worthwhile adding
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// for efficiency.
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const G4Axis2Placement3D& pos= *(GetPosition());
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G4Point3D p= pos.GetToPlacementCoordinates() * cp.GetPoint();
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v= p.y()*pos.GetPX() + (2*focalDist)*pos.GetPY();
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return true;
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}
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