Method EvaluateFunction

Common/DataModel/vtkImplicitSelectionLoop.cxx:92–132

------------------------------------------------------------------------------ Evaluate plane equations. Return smallest absolute value.

//------------------------------------------------------------------------------
// Evaluate plane equations. Return smallest absolute value.
double vtkImplicitSelectionLoop::EvaluateFunction(double x[3])
{
  int i, numPts;
  double xProj[3];
  double t, dist2, minDist2, closest[3];
  int inside = 0;

  if (this->InitializationTime < this->GetMTime())
  {
    this->Initialize();
  }
  // Initialize may change the number of points
  numPts = this->Polygon->Points->GetNumberOfPoints();

  // project point onto plane
  vtkPlane::ProjectPoint(x, this->Origin, this->Normal, xProj);

  // determine whether it's in the selection loop and then evaluate point
  // in polygon only if absolutely necessary.
  if (xProj[0] >= this->Bounds[0] && xProj[0] <= this->Bounds[1] && xProj[1] >= this->Bounds[2] &&
    xProj[1] <= this->Bounds[3] && xProj[2] >= this->Bounds[4] && xProj[2] <= this->Bounds[5] &&
    vtkPolygon::PointInPolygon(xProj, numPts,
      vtkArrayDownCast<vtkDoubleArray>(this->Polygon->Points->GetData())->GetPointer(0),
      this->Bounds, this->Normal) == 1)
  {
    inside = 1;
  }

  // determine distance to boundary
  for (minDist2 = VTK_DOUBLE_MAX, i = 0; i < numPts; i++)
  {
    double p1[3], p2[3];
    this->Polygon->Points->GetPoint(i, p1);
    this->Polygon->Points->GetPoint((i + 1) % numPts, p2);
    dist2 = vtkLine::DistanceToLine(xProj, p1, p2, t, closest);
    minDist2 = std::min(dist2, minDist2);
  }

  minDist2 = sqrt(minDist2);
  return (inside ? -minDist2 : minDist2);
}

//------------------------------------------------------------------------------
// Evaluate gradient of the implicit function. Use a numerical scheme: evaluate