Method ComputeBounds

Common/DataModel/vtkImageData.cxx:444–521

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

//------------------------------------------------------------------------------
void vtkImageData::ComputeBounds()
{
  if (this->GetMTime() <= this->ComputeTime)
  {
    return;
  }
  const int* extent = this->GetExtent();

  if (extent[0] > extent[1] || extent[2] > extent[3] || extent[4] > extent[5])
  {
    vtkMath::UninitializeBounds(this->Bounds);
  }
  else
  {
    if (this->DirectionMatrixIsIdentity)
    {
      // Direction is identity: bounds are easy to compute
      // with only origin and spacing
      const double* origin = this->Origin;
      const double* spacing = this->Spacing;
      int swapXBounds = (spacing[0] < 0); // 1 if true, 0 if false
      int swapYBounds = (spacing[1] < 0); // 1 if true, 0 if false
      int swapZBounds = (spacing[2] < 0); // 1 if true, 0 if false

      this->Bounds[0] = origin[0] + (extent[0 + swapXBounds] * spacing[0]);
      this->Bounds[2] = origin[1] + (extent[2 + swapYBounds] * spacing[1]);
      this->Bounds[4] = origin[2] + (extent[4 + swapZBounds] * spacing[2]);

      this->Bounds[1] = origin[0] + (extent[1 - swapXBounds] * spacing[0]);
      this->Bounds[3] = origin[1] + (extent[3 - swapYBounds] * spacing[1]);
      this->Bounds[5] = origin[2] + (extent[5 - swapZBounds] * spacing[2]);
    }
    else
    {
      // Direction isn't identity: use IndexToPhysical matrix
      // to determine the position of the dataset corners
      int iMin, iMax, jMin, jMax, kMin, kMax;
      iMin = extent[0];
      iMax = extent[1];
      jMin = extent[2];
      jMax = extent[3];
      kMin = extent[4];
      kMax = extent[5];
      int ijkCorners[8][3] = {
        { iMin, jMin, kMin },
        { iMax, jMin, kMin },
        { iMin, jMax, kMin },
        { iMax, jMax, kMin },
        { iMin, jMin, kMax },
        { iMax, jMin, kMax },
        { iMin, jMax, kMax },
        { iMax, jMax, kMax },
      };

      double xyz[3];
      double xMin, xMax, yMin, yMax, zMin, zMax;
      xMin = yMin = zMin = VTK_DOUBLE_MAX;
      xMax = yMax = zMax = VTK_DOUBLE_MIN;