Gabriele Cosmo
84 lines
2.0 KiB
C++
84 lines
2.0 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: G4LineSection.cc,v 1.4 2000/11/01 15:15:53 gcosmo Exp $
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// GEANT4 tag $Name: geant4-03-01 $
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//
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// typedef double G4double;
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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),
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VecAtoB(PntB-PntA)
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{
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G4double distABsquared = VecAtoB.mag2() ;
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if ( distABsquared == 0.0)
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{
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G4Exception("Equal points in G4LineSection::G4LineSection: line->point ?") ;
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}
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else
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{
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inverse_square_distAB=1.0 / distABsquared ;
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}
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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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unit_projection= inner_prod * InvsqDistAB();
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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. )
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{
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// A is the closest point
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dist_sq= sq_VecAZ;
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}
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else
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{
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// B is the closest point
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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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if( dist_sq < 0.0 ) dist_sq = 0.0 ;
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return sqrt(dist_sq) ;
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}
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G4double G4LineSection::Distline( const G4ThreeVector& OtherPnt,
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const G4ThreeVector& LinePntA,
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const G4ThreeVector& LinePntB )
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{
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G4LineSection LineAB( LinePntA, LinePntB ); // Line from A to B
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return LineAB.Dist( OtherPnt );
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}
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