Method LassoSelectInternal

Views/Infovis/vtkParallelCoordinatesRepresentation.cxx:1439–1492

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//------------------------------------------------------------------------------
void vtkParallelCoordinatesRepresentation::LassoSelectInternal(
  vtkPoints* brushPoints, vtkIdTypeArray* outIds)
{
  if (brushPoints->GetNumberOfPoints() <= 0)
    return;

  double* p = brushPoints->GetPoint(0);
  int position = this->ComputePointPosition(p);

  if (position < 0 || position >= this->NumberOfAxes)
    return;

  double leftAxisRange[2], rightAxisRange[2];
  leftAxisRange[0] = leftAxisRange[1] = rightAxisRange[0] = rightAxisRange[1] = 0;
  this->GetRangeAtPosition(position, leftAxisRange);
  this->GetRangeAtPosition(position + 1, rightAxisRange);

  double dLeft = leftAxisRange[1] - leftAxisRange[0];
  double dRight = rightAxisRange[1] - rightAxisRange[0];
  double dy = this->YMax - this->YMin;

  this->LinearThreshold->Initialize();
  this->LinearThreshold->SetLinearThresholdTypeToBetween();
  this->LinearThreshold->SetDistanceThreshold(this->AngleBrushThreshold);
  this->LinearThreshold->UseNormalizedDistanceOn();
  this->LinearThreshold->SetColumnRanges(dLeft, dRight);
  this->LinearThreshold->AddColumnToThreshold(position, 0);
  this->LinearThreshold->AddColumnToThreshold(position + 1, 0);

  // add a line equation for each brush point
  for (int i = 0; i < brushPoints->GetNumberOfPoints(); i++)
  {
    p = brushPoints->GetPoint(i);

    // normalize p into [0,1]x[0,1]
    double pn[2] = { (p[0] - this->Xs[position]) / (this->Xs[position + 1] - this->Xs[position]),
      (p[1] - this->YMin) / dy };

    // now compute actual data values for two PC lines passing through pn,
    // starting from the endpoints of the left axis
    double q[2] = { leftAxisRange[0], rightAxisRange[0] + pn[1] / pn[0] * dRight };

    double r[2] = { leftAxisRange[1], rightAxisRange[0] + (1.0 + (pn[1] - 1.0) / pn[0]) * dRight };

    this->LinearThreshold->AddLineEquation(q, r);
  }

  this->LinearThreshold->Update();
  vtkIdTypeArray* ids = this->LinearThreshold->GetSelectedRowIds();
  for (int i = 0; i < ids->GetNumberOfTuples(); i++)
  {
    outIds->InsertNextTuple(i, ids);
  }
}
//------------------------------------------------------------------------------
// All lines that have the same slope in PC space represent a set of points
// that define a line in XY space.  PC lines that have similar slope are all