Method PixelizeImage

Filters/Hybrid/vtkImageToPolyDataFilter.cxx:193–257

}

void vtkImageToPolyDataFilter::PixelizeImage(vtkUnsignedCharArray* pixels, int dims[3],
  double origin[3], double spacing[3], vtkPolyData* output)
{
  int numPts, numCells, i, j, id;
  vtkIdType pts[4];
  vtkPoints* newPts;
  vtkCellArray* newPolys;
  double x[3];
  vtkUnsignedCharArray* polyColors;
  unsigned char *ptr, *colors = pixels->GetPointer(0);

  // create the points - see whether to create or append
  numPts = (dims[0] + 1) * (dims[1] + 1);
  newPts = vtkPoints::New();
  newPts->SetNumberOfPoints(numPts);

  x[2] = 0.0;
  for (id = 0, j = 0; j <= dims[1]; j++)
  {
    x[1] = origin[1] + j * spacing[1];
    for (i = 0; i <= dims[0]; i++)
    {
      x[0] = origin[0] + i * spacing[0];
      newPts->SetPoint(id, x);
      id++;
    }
  }
  output->SetPoints(newPts);
  newPts->Delete();

  // create the cells and cell colors
  //
  numCells = dims[0] * dims[1];
  newPolys = vtkCellArray::New();
  newPolys->AllocateEstimate(numCells, 4);

  polyColors = vtkUnsignedCharArray::New();
  polyColors->SetNumberOfValues(3 * numCells); // for rgb
  polyColors->SetNumberOfComponents(3);

  // loop over all pixels, creating a quad per pixel.
  // Note: copying point data (pixel values) to cell data (quad colors).
  for (id = 0, j = 0; j < dims[1]; j++)
  {
    for (i = 0; i < dims[0]; i++)
    {
      pts[0] = i + j * (dims[0] + 1);
      pts[1] = pts[0] + 1;
      pts[2] = pts[1] + dims[0] + 1;
      pts[3] = pts[2] - 1;
      newPolys->InsertNextCell(4, pts);
      ptr = colors + 3 * id;
      polyColors->SetValue(3 * id, ptr[0]);
      polyColors->SetValue(3 * id + 1, ptr[1]);
      polyColors->SetValue(3 * id + 2, ptr[2]);
      id++;
    }
  }