Method EvaluateFunction

Common/DataModel/vtkPolyPlane.cxx:133–271

------------------------------------------------------------------------------ Evaluate the distance to the poly plane for point x[3].

//------------------------------------------------------------------------------
// Evaluate the distance to the poly plane for point x[3].
double vtkPolyPlane::EvaluateFunction(double x[3])
{
  // Sanity check
  if (!this->PolyLine || !this->PolyLine->GetPoints())
  {
    return 0;
  }

  double xFlat[3] = { x[0], x[1], 0.0 };

  // No error checking, for speed... We will assume that we have a polyline
  // and that it has at least 2 points.
  // traverse the list of points in the polyline.
  vtkPoints* points = this->PolyLine->GetPoints();

  const vtkIdType nPoints = points->GetNumberOfPoints();
  const vtkIdType nLines = nPoints - 1;

  // At least 2 points needed to define a polyplane.
  if (nLines < 1)
  {
    return 0;
  }

  // compute normals
  this->ComputeNormals();

  double p1[3], p2[3], t, closest[3];
  double minDistance2 = VTK_DOUBLE_MAX, distance2, signedDistance = VTK_DOUBLE_MAX, sign = 1;

  // Iterate through all the lines.

  for (int pIdx = 0; pIdx < nLines; ++pIdx)
  {

    // Get the end points of this line segment in the polyline
    points->GetPoint(pIdx, p1);
    points->GetPoint(pIdx + 1, p2);

    // Flatten it.
    p1[2] = 0;
    p2[2] = 0;

    // Compute distance-squared to finite line. Store the closest point.
    distance2 = vtkLine::DistanceToLine(xFlat, p1, p2, t, closest);

    // if the closest point on the line is on the segment
    if (t >= 0 && t <= 1)
    {
      // if this is the minimum distance found, use that distance
      // and record whether it was right of or left of the line
      if (distance2 < minDistance2)
      {
        minDistance2 = distance2;
        sign = leftOf(p1, p2, xFlat) ? 1 : -1;
      }
    }
    // if the closest point on the line is before the segment starts