Method IntersectVolumeWithLine

Rendering/Core/vtkCellPicker.cxx:981–1265

#define VTKCELLPICKER_VOXEL_TOL 1e-6

double vtkCellPicker::IntersectVolumeWithLine(const double p1[3], const double p2[3], double t1,
  double t2, vtkProp3D* prop, vtkAbstractVolumeMapper* mapper)
{
  vtkImageData* data = vtkImageData::SafeDownCast(mapper->GetDataSetInput());

  if (data == nullptr)
  {
    // This picker only works with image inputs
    return VTK_DOUBLE_MAX;
  }

  // Convert ray to structured coordinates
  double spacing[3], origin[3];
  int extent[6];
  data->GetSpacing(spacing);
  data->GetOrigin(origin);
  data->GetExtent(extent);

  double x1[3], x2[3];
  for (int i = 0; i < 3; i++)
  {
    x1[i] = (p1[i] - origin[i]) / spacing[i];
    x2[i] = (p2[i] - origin[i]) / spacing[i];
  }

  // Clip the ray with the extent, results go in s1 and s2
  int planeId;
  double s1, s2;
  if (!vtkCellPicker::ClipLineWithExtent(extent, x1, x2, s1, s2, planeId))
  {
    return VTK_DOUBLE_MAX;
  }
  t1 = std::max(s1, t1);
  t2 = std::min(s2, t2);

  // Sanity check
  if (t2 < t1)
  {
    return VTK_DOUBLE_MAX;
  }

  // Get the property from the volume or the LOD
  vtkVolumeProperty* property = nullptr;
  vtkVolume* volume = nullptr;
  vtkLODProp3D* lodVolume = nullptr;
  if ((volume = vtkVolume::SafeDownCast(prop)))
  {
    property = volume->GetProperty();
  }
  else if ((lodVolume = vtkLODProp3D::SafeDownCast(prop)))
  {
    int lodId = lodVolume->GetPickLODID();
    lodVolume->GetLODProperty(lodId, &property);
  }

  // Get the threshold for the opacity
  double opacityThreshold = this->VolumeOpacityIsovalue;