Method IntersectImageWithLine

Rendering/Core/vtkCellPicker.cxx:1268–1376

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
double vtkCellPicker::IntersectImageWithLine(const double p1[3], const double p2[3], double t1,
  double t2, vtkProp3D* prop, vtkImageMapper3D* imageMapper)
{
  // Get the image information
  vtkImageData* data = imageMapper->GetInput();
  int extent[6];
  data->GetExtent(extent);

  // Get the plane equation for the slice
  double normal[4];
  imageMapper->GetSlicePlaneInDataCoords(prop->GetMatrix(), normal);

  // Point the normal towards camera
  if (normal[0] * (p1[0] - p2[0]) + normal[1] * (p1[1] - p2[1]) + normal[2] * (p1[2] - p2[2]) < 0)
  {
    normal[0] = -normal[0];
    normal[1] = -normal[1];
    normal[2] = -normal[2];
    normal[3] = -normal[3];
  }

  // And convert plane eqn to structured coords
  double xnormal[4];
  data->TransformPhysicalPlaneToContinuousIndex(normal, xnormal);

  // Also convert ray to structured coords
  double x1[3], x2[3];
  data->TransformPhysicalPointToContinuousIndex(p1, x1);
  data->TransformPhysicalPointToContinuousIndex(p2, x2);

  // Get the bounds to discover any cropping that has been applied
  double bounds[6];
  imageMapper->GetIndexBounds(bounds);

  // Clip the ray with the extent
  int planeId, plane2Id;
  double tMin, tMax;
  if (!vtkBox::IntersectWithLine(bounds, x1, x2, tMin, tMax, nullptr, nullptr, planeId, plane2Id))
  {
    return VTK_DOUBLE_MAX;
  }

  if (tMin != tMax)
  {
    // Intersect the ray with the slice plane
    double w1 = vtkMath::Dot(x1, xnormal) + xnormal[3];
    double w2 = vtkMath::Dot(x2, xnormal) + xnormal[3];
    if (w1 * w2 > VTKCELLPICKER_VOXEL_TOL)
    {
      return VTK_DOUBLE_MAX;
    }
    if (w1 * w2 < 0)
    {
      tMin = w1 / (w1 - w2);
    }
  }

  // Make sure that intersection is within clipping planes