Gabriele Cosmo
87 lines
3.2 KiB
C++
87 lines
3.2 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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// G4LineSection implementation
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//
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// Created: J.Apostolakis, 1999
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// --------------------------------------------------------------------
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#include "G4LineSection.hh"
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G4LineSection::G4LineSection( const G4ThreeVector& PntA,
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const G4ThreeVector& PntB )
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: EndpointA(PntA), VecAtoB(PntB-PntA)
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{
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fABdistanceSq = VecAtoB.mag2();
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}
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G4double G4LineSection::Dist( G4ThreeVector OtherPnt ) const
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{
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G4double dist_sq;
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G4ThreeVector VecAZ;
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G4double sq_VecAZ, inner_prod, unit_projection ;
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VecAZ= OtherPnt - EndpointA;
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sq_VecAZ = VecAZ.mag2();
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inner_prod= VecAtoB.dot( VecAZ );
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// Determine Projection(AZ on AB) / Length(AB)
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//
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if( fABdistanceSq != 0.0 )
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{
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// unit_projection= inner_prod * InvsqDistAB();
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unit_projection = inner_prod/fABdistanceSq;
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if( (0. <= unit_projection ) && (unit_projection <= 1.0 ) )
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{
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dist_sq= sq_VecAZ - unit_projection * inner_prod ;
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}
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else
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{
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// The perpendicular from the point to the line AB meets the line
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// in a point outside the line segment!
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if( unit_projection < 0. ) // A is the closest point
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{
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dist_sq= sq_VecAZ;
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}
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else // B is the closest point
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{
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G4ThreeVector EndpointB = EndpointA + VecAtoB;
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G4ThreeVector VecBZ = OtherPnt - EndpointB;
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dist_sq = VecBZ.mag2();
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}
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}
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}
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else
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{
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dist_sq = (OtherPnt - EndpointA).mag2() ;
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}
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if( dist_sq < 0.0 ) dist_sq = 0.0 ;
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return std::sqrt(dist_sq) ;
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}
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