larcorealg/larcorealg/GeoAlgo/GeoCylinder.cxx

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#include "larcorealg/GeoAlgo/GeoAlgoException.h"
#include "larcorealg/GeoAlgo/GeoCylinder.h"

namespace geoalgo {

  Cylinder::Cylinder()
    : Line()
    , _radius (0.)
  {}

  Cylinder::Cylinder(const double x_min, const double y_min, const double z_min,
                     const double x_max, const double y_max, const double z_max,
                     const double radius)
    : Line(x_min, y_min, z_min, x_max, y_max, z_max)
    , _radius ( radius )
  {}

  Cylinder::Cylinder(const Point_t& min, const Vector_t& max, const double radius)
    : Line(min, max)
    , _radius ( radius )
  {
    if(min.size()!=3 || max.size()!=3)
      throw GeoAlgoException("Cylinder ctor accepts only 3D Point!");
  }

  bool Cylinder::Contain(const Point_t &pt) const {

    // get a vector that defines the axis of the cylinder
    Vector_t axis = _pt1-_pt2;
    Vector_t dirpt = pt-_pt2;

    // angle of point w.r.t. the axis
    double angleMin = axis.Angle(dirpt);

    // if the angle is > 90 -> outside -> return
    if (angleMin > 0.5*3.14)
      return false;

    // revert the axis direction
    axis = _pt2-_pt1;
    dirpt = pt-_pt1;
    angleMin = axis.Angle(dirpt);

    // if the angle is > 90 -> outside -> return
    if (angleMin > 0.5*3.14)
      return false;

    // if still here, all that is left to verify is
    // that the point isn't more than a radius
    // away from the cylinder axis
    // 1) make a line corresponding to the axis
    // 2) get the distance between the point and the line
    double radial_dist_sq = _geoAlgo.SqDist(*this,pt);

    if (radial_dist_sq > _radius*_radius)
      return false;

    return true;

  }
}