Method IntersectHyperTreeGridWithLine

Rendering/Core/vtkCellPicker.cxx:752–929

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double vtkCellPicker::IntersectHyperTreeGridWithLine(const double p1[3], const double p2[3],
  double t1, double t2, vtkAbstractHyperTreeGridMapper* mapper)
{
  // Retrieve input grid
  vtkUniformHyperTreeGrid* grid = vtkUniformHyperTreeGrid::SafeDownCast(mapper->GetDataSetInput());
  if (grid == nullptr)
  {
    // This picker works only with uniform hypertree grid inputs
    return VTK_DOUBLE_MAX;
  }

  // Retrieve grid dimensionality
  unsigned int dimension = grid->GetDimension();
  if (dimension != 2)
  {
    // This picker works only with 2-dimensional uniform hypertree grids
    return VTK_DOUBLE_MAX;
  }

  // Retrieve grid topology and geometry
  double origin[3];
  grid->GetOrigin(origin);
  double scale[3];
  grid->GetGridScale(scale);
  int extent[6];
  grid->GetExtent(extent);

  // Determine normal vector of the grid
  double normal[] = { 0., 0., 0., 1. };
  unsigned int orientation = grid->GetOrientation();
  if (p1[orientation] - p2[orientation] > 0)
  {
    normal[orientation] = 1.;
    normal[3] = 1.;
  }
  else
  {
    normal[orientation] = -1.;
    normal[3] = -1.;
  }
  normal[3] += vtkMath::Dot(origin, normal);
  double norm = vtkMath::Norm(normal);
  normal[orientation] /= norm;
  normal[3] /= norm;

  // Determine grid principal axes
  unsigned axis1, axis2;
  if (orientation == 2)
  {
    axis1 = 0;
    axis2 = 1;
  }
  else if (orientation == 1)
  {
    axis1 = 0;
    axis2 = 2;
  }
  else