Method EvaluatePosition

Common/DataModel/vtkPolygon.cxx:383–461

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int vtkPolygon::EvaluatePosition(const double x[3], double closestPoint[3], int& subId,
  double pcoords[3], double& minDist2, double weights[])
{
  int i;
  double p0[3], p10[3], l10, p20[3], l20, n[3], cp[3];
  double ray[3], bounds[6];

  subId = 0;
  this->ParameterizePolygon(p0, p10, l10, p20, l20, n);
  this->InterpolateFunctions(x, weights);
  vtkPlane::ProjectPoint(x, p0, n, cp);

  for (i = 0; i < 3; i++)
  {
    ray[i] = cp[i] - p0[i];
  }
  pcoords[0] = vtkMath::Dot(ray, p10) / (l10 * l10);
  pcoords[1] = vtkMath::Dot(ray, p20) / (l20 * l20);
  pcoords[2] = 0.0;

  // Make sure that the bounding box has non-zero volume, so that all
  // bounding box sides have non-zero thickness. This prevents tolerancing
  // issues when the polygon lies exactly on a coordinate plane.
  vtkBoundingBox bbox(this->GetBounds());
  bbox.InflateSlice(VTK_POLYGON_TOL);
  bbox.GetBounds(bounds);

  if (pcoords[0] >= 0.0 && pcoords[0] <= 1.0 && pcoords[1] >= 0.0 && pcoords[1] <= 1.0 &&
    (vtkPolygon::PointInPolygon(cp, this->Points->GetNumberOfPoints(),
       static_cast<vtkDoubleArray*>(this->Points->GetData())->GetPointer(0), bounds,
       n) == VTK_POLYGON_INSIDE))
  {
    if (closestPoint)
    {
      closestPoint[0] = cp[0];
      closestPoint[1] = cp[1];
      closestPoint[2] = cp[2];
      minDist2 = vtkMath::Distance2BetweenPoints(x, closestPoint);
    }
    return 1;
  }

  // If here, point is outside of polygon, so need to find distance to boundary
  //
  else
  {
    double t, dist2;
    int numPts;
    double closest[3];
    const double *pt1, *pt2;

    if (closestPoint)
    {
      numPts = this->Points->GetNumberOfPoints();
      // Efficient point access
      const auto pointsArray = vtkDoubleArray::FastDownCast(this->Points->GetData());
      if (!pointsArray)
      {