G4VoxelLimits.cc

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//
// Class G4VoxelLimits implementation
//
// 13.07.95, P.Kent - Initial version
// --------------------------------------------------------------------
 
#include "G4VoxelLimits.hh"
 
#include "G4ios.hh"
 
///////////////////////////////////////////////////////////////////////////
//
// Further restrict limits
// No checks for illegal restrictions
//
void G4VoxelLimits::AddLimit( const EAxis pAxis, 
                              const G4double pMin,
                              const G4double pMax )
{
  if ( pAxis == kXAxis )
  {
    if ( pMin > fxAxisMin ) fxAxisMin = pMin ;    
    if ( pMax < fxAxisMax ) fxAxisMax = pMax ;    
  }
  else if ( pAxis == kYAxis )
  {
    if ( pMin > fyAxisMin ) fyAxisMin = pMin ;    
    if ( pMax < fyAxisMax ) fyAxisMax = pMax ;
  }
  else
  { 
    assert( pAxis == kZAxis ) ;
 
    if ( pMin > fzAxisMin ) fzAxisMin = pMin ;
    if ( pMax < fzAxisMax ) fzAxisMax = pMax ;
  }
}
 
///////////////////////////////////////////////////////////////////////////
//
// ClipToLimits
//
// Clip the line segment pStart->pEnd to the volume described by the
// current limits. Return true if the line remains after clipping,
// else false, and leave the vectors in an undefined state.
//
// Process:
//
// Use Cohen-Sutherland clipping in 3D
// [Fundamentals of Interactive Computer Graphics,Foley & Van Dam]
//
G4bool G4VoxelLimits::ClipToLimits( G4ThreeVector& pStart,
                                    G4ThreeVector& pEnd      ) const
{
  G4int sCode, eCode ;
  G4bool remainsAfterClip ;
    
  // Determine if line is trivially inside (both outcodes==0) or outside
  // (logical AND of outcodes !=0)
 
  sCode = OutCode(pStart) ;
  eCode = OutCode(pEnd)   ;
 
  if ( (sCode & eCode) != 0 )
  {
    // Trivially outside, no intersection with region
 
    remainsAfterClip = false;
  }
  else if ( sCode == 0 && eCode == 0 )
  {
    // Trivially inside, no intersections
 
    remainsAfterClip = true ;
  }
  else
  {
    // Line segment *may* cut volume boundaries
    // At most, one end point is inside
 
    G4double x1, y1, z1, x2, y2, z2 ;
 
    x1 = pStart.x() ;
    y1 = pStart.y() ;
    z1 = pStart.z() ;
 
    x2 = pEnd.x() ;
    y2 = pEnd.y() ;
    z2 = pEnd.z() ;
 
    while ( sCode != eCode )  // Loop checking, 06.08.2015, G.Cosmo
    {
      // Copy vectors to work variables x1-z1,x2-z2
      // Ensure x1-z1 lies outside volume, swapping vectors and outcodes
      // if necessary
 
      if ( sCode != 0 )
      {
        if ( (sCode & 0x01) != 0 )  // Clip against fxAxisMin
        {
          z1 += (fxAxisMin-x1)*(z2-z1)/(x2-x1);
          y1 += (fxAxisMin-x1)*(y2-y1)/(x2-x1);
          x1  = fxAxisMin;
        }
        else if ( (sCode & 0x02) != 0 ) // Clip against fxAxisMax
        {
          z1 += (fxAxisMax-x1)*(z2-z1)/(x2-x1);
          y1 += (fxAxisMax-x1)*(y2-y1)/(x2-x1);
          x1  = fxAxisMax ;
        }
        else if ( (sCode & 0x04) != 0 )  // Clip against fyAxisMin
        {
          x1 += (fyAxisMin-y1)*(x2-x1)/(y2-y1);
          z1 += (fyAxisMin-y1)*(z2-z1)/(y2-y1);
          y1  = fyAxisMin;
        }
        else if ( (sCode & 0x08) != 0 )  // Clip against fyAxisMax
        {
          x1 += (fyAxisMax-y1)*(x2-x1)/(y2-y1);
          z1 += (fyAxisMax-y1)*(z2-z1)/(y2-y1);
          y1  = fyAxisMax;
        }
        else if ( (sCode & 0x10) != 0 )  // Clip against fzAxisMin
        {
          x1 += (fzAxisMin-z1)*(x2-x1)/(z2-z1);
          y1 += (fzAxisMin-z1)*(y2-y1)/(z2-z1);
          z1  = fzAxisMin;
        }
        else if ( (sCode & 0x20) != 0 )  // Clip against fzAxisMax
        {
          x1 += (fzAxisMax-z1)*(x2-x1)/(z2-z1);
          y1 += (fzAxisMax-z1)*(y2-y1)/(z2-z1);
          z1  = fzAxisMax;
        }
      }
      if ( eCode != 0 )  // Clip 2nd end: repeat of 1st, but 1<>2
      {
        if ( (eCode & 0x01) != 0 )  // Clip against fxAxisMin
        {
          z2 += (fxAxisMin-x2)*(z1-z2)/(x1-x2);
          y2 += (fxAxisMin-x2)*(y1-y2)/(x1-x2);
          x2  = fxAxisMin;
        }
        else if ( (eCode & 0x02) != 0 )  // Clip against fxAxisMax
        {
          z2 += (fxAxisMax-x2)*(z1-z2)/(x1-x2);
          y2 += (fxAxisMax-x2)*(y1-y2)/(x1-x2);
          x2  = fxAxisMax;
        }
        else if ( (eCode & 0x04) != 0 )  // Clip against fyAxisMin
        {
          x2 += (fyAxisMin-y2)*(x1-x2)/(y1-y2);
          z2 += (fyAxisMin-y2)*(z1-z2)/(y1-y2);
          y2  = fyAxisMin;
        }
        else if ((eCode&0x08) != 0)  // Clip against fyAxisMax
        {
          x2 += (fyAxisMax-y2)*(x1-x2)/(y1-y2);
          z2 += (fyAxisMax-y2)*(z1-z2)/(y1-y2);
          y2  = fyAxisMax;
        }
        else if ( (eCode & 0x10) != 0 )  // Clip against fzAxisMin
        {
          x2 += (fzAxisMin-z2)*(x1-x2)/(z1-z2);
          y2 += (fzAxisMin-z2)*(y1-y2)/(z1-z2);
          z2  = fzAxisMin;
        }
        else if ( (eCode & 0x20) != 0 )  // Clip against fzAxisMax
        {
          x2 += (fzAxisMax-z2)*(x1-x2)/(z1-z2);
          y2 += (fzAxisMax-z2)*(y1-y2)/(z1-z2);
          z2  = fzAxisMax;
        }
      }
      pStart = G4ThreeVector(x1,y1,z1);
      pEnd   = G4ThreeVector(x2,y2,z2);
      sCode  = OutCode(pStart);
      eCode  = OutCode(pEnd);
    }
    remainsAfterClip = sCode == 0 && eCode == 0;
  }
  return remainsAfterClip;
}
 
////////////////////////////////////////////////////////////////////////////
//
// Calculate the `outcode' for the specified vector:
// The following bits are set:
//   0      pVec.x()<fxAxisMin && IsXLimited()
//   1      pVec.x()>fxAxisMax && IsXLimited()
//   2      pVec.y()<fyAxisMin && IsYLimited()
//   3      pVec.y()>fyAxisMax && IsYLimited()
//   4      pVec.z()<fzAxisMin && IsZLimited()
//   5      pVec.z()>fzAxisMax && IsZLimited()
//
G4int G4VoxelLimits::OutCode( const G4ThreeVector& pVec ) const
{
  G4int code = 0 ;                // The outcode
 
  if ( IsXLimited() )
  {
    if ( pVec.x() < fxAxisMin ) code |= 0x01 ;
    if ( pVec.x() > fxAxisMax ) code |= 0x02 ;
  }
  if ( IsYLimited() )
  {
    if ( pVec.y() < fyAxisMin ) code |= 0x04 ;
    if ( pVec.y() > fyAxisMax ) code |= 0x08 ;
  }
  if (IsZLimited())
  {
    if ( pVec.z() < fzAxisMin ) code |= 0x10 ;
    if ( pVec.z() > fzAxisMax ) code |= 0x20 ;
  }
  return code;
}
 
///////////////////////////////////////////////////////////////////////////////
 
std::ostream& operator << (std::ostream& os, const G4VoxelLimits& pLim)
{
    os << "{";
    if (pLim.IsXLimited())
        {
            os << "(" << pLim.GetMinXExtent() 
               << "," << pLim.GetMaxXExtent() << ") ";
        }
    else
        {
            os << "(-,-) ";
        }
    if (pLim.IsYLimited())
        {
            os << "(" << pLim.GetMinYExtent() 
               << "," << pLim.GetMaxYExtent() << ") ";
        }
    else
        {
            os << "(-,-) ";
        }
    if (pLim.IsZLimited())
        {
            os << "(" << pLim.GetMinZExtent()
               << "," << pLim.GetMaxZExtent() << ")";
        }
    else
        {
            os << "(-,-)";
        }
    os << "}";
    return os;
}