Method SetBrushLine

Views/Infovis/vtkParallelCoordinatesView.cxx:426–536

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int vtkParallelCoordinatesView::SetBrushLine(int line, double* p1, double* p2)
{
  double p1x = p1[0], p1y = p1[1];
  double p2x = p2[0], p2y = p2[1];
  vtkParallelCoordinatesRepresentation* rep =
    vtkParallelCoordinatesRepresentation::SafeDownCast(this->GetRepresentation());
  int numAxes = rep->GetNumberOfAxes();
  double* xs = new double[numAxes];
  rep->GetXCoordinatesOfPositions(xs);

  if (p1x == p2x)
  {
    delete[] xs;
    return 0;
  }

  // swap, if necessary...I don't think the splines like being out of order
  if (p1x > p2x)
  {
    double tmp;
    tmp = p1x;
    p1x = p2x;
    p2x = tmp;
    tmp = p1y;
    p1y = p2y;
    p2y = tmp;
  }

  // find the axis to the left of p1
  int left = numAxes - 1;
  for (int i = 0; i < numAxes; i++)
  {
    if (p1x > xs[i])
    {
      left = i;
    }
    else
    {
      break;
    }
  }

  int right = left + 1;

  // sanity check
  if (right >= numAxes || left < 0)
  {
    delete[] xs;
    return 0;
  }

  // find the points that line (p1-p2) intersects on the left/right axes
  double m = (p2y - p1y) / (p2x - p1x);
  double lefty = p1y - m * (p1x - xs[left]);
  double righty = p1y - m * (p1x - xs[right]);

  p1x = xs[left];
  p2x = xs[right];