Method Crop

Common/DataModel/vtkStructuredGrid.cxx:511–614

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkStructuredGrid::Crop(const int* updateExtent)
{
  // Do nothing for empty datasets:
  for (int dim = 0; dim < 3; ++dim)
  {
    if (this->Extent[2 * dim] > this->Extent[2 * dim + 1])
    {
      vtkDebugMacro(<< "Refusing to crop empty dataset.");
      return;
    }
  }

  int i, j, k;
  int uExt[6];
  const int* extent = this->Extent;

  // If the update extent is larger than the extent,
  // we cannot do anything about it here.
  for (i = 0; i < 3; ++i)
  {
    uExt[i * 2] = updateExtent[i * 2];
    uExt[i * 2] = std::max(uExt[i * 2], extent[i * 2]);
    uExt[i * 2 + 1] = updateExtent[i * 2 + 1];
    uExt[i * 2 + 1] = std::min(uExt[i * 2 + 1], extent[i * 2 + 1]);
  }

  // If extents already match, then we need to do nothing.
  if (extent[0] == uExt[0] && extent[1] == uExt[1] && extent[2] == uExt[2] &&
    extent[3] == uExt[3] && extent[4] == uExt[4] && extent[5] == uExt[5])
  {
    return;
  }
  else
  {
    // Get the points.  Protect against empty data objects.
    vtkPoints* inPts = this->GetPoints();
    if (inPts == nullptr)
    {
      return;
    }

    vtkDebugMacro(<< "Cropping Grid");

    vtkStructuredGrid* newGrid = vtkStructuredGrid::New();
    vtkPointData* inPD = this->GetPointData();
    vtkCellData* inCD = this->GetCellData();
    vtkPointData* outPD = newGrid->GetPointData();
    vtkCellData* outCD = newGrid->GetCellData();

    // Allocate necessary objects
    //
    newGrid->SetExtent(uExt);
    int outSize = (uExt[1] - uExt[0] + 1) * (uExt[3] - uExt[2] + 1) * (uExt[5] - uExt[4] + 1);
    vtkPoints* newPts = inPts->NewInstance();
    newPts->SetDataType(inPts->GetDataType());
    newPts->SetNumberOfPoints(outSize);
    outPD->CopyAllocate(inPD, outSize, outSize);
    outCD->CopyAllocate(inCD, outSize, outSize);