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Cylinder.cc

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#include "DataFormats/GeometrySurface/interface/Cylinder.h"
#include "DataFormats/GeometrySurface/interface/TangentPlane.h"
#include "DataFormats/GeometrySurface/interface/GeomExceptions.h"

#include <cfloat>

Surface::Side Cylinder::side( const LocalPoint& p, Scalar toler) const
{
  Scalar lz = p.perp() - radius();
  return (fabs(lz)<toler ? SurfaceOrientation::onSurface : 
          (lz>0 ? SurfaceOrientation::positiveSide : SurfaceOrientation::negativeSide));
}

ReferenceCountingPointer<TangentPlane> 
Cylinder::tangentPlane (const LocalPoint& aPoint) const
{
  return tangentPlane(toGlobal(aPoint));
}

ReferenceCountingPointer<TangentPlane> 
Cylinder::tangentPlane (const GlobalPoint& aPoint) const
{
  //
  // Tangent plane at specified point. In order to avoid
  // possible numerical problems currently no attempt is made 
  // to verify, if the point is actually on the cylinder.
  //
  // local y parallel to axis
  GlobalVector yPlane(toGlobal(LocalVector(0.,0.,1.)));
  // local x normal to y and a vector linking the specified
  // point with the axis
  GlobalVector xPlane(yPlane.cross(aPoint-position()));
  Scalar size = xPlane.mag();
  if ( size<FLT_MIN ) 
    throw GeometryError("Attempt to construct TangentPlane on cylinder axis");
  xPlane /= size;
//   // local z defined by x and y (should point outwards from axis)
//   GlobalVector zPlane(xPlane.cross(yPlane));

  return ReferenceCountingPointer<TangentPlane>(new TangentPlane(aPoint,
                                                                 RotationType(xPlane,
                                                                              yPlane),
                                                                 this));
}

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