Method GenerateHash

Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx:239–281

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//------------------------------------------------------------------------------
vtkPolyDataMapper::MapperHashType vtkOpenGLPolyDataMapper::GenerateHash(vtkPolyData* polydata)
{
  int cellFlag = 0;
  vtkAbstractArray* scalars = this->GetAbstractScalars(
    polydata, this->ScalarMode, this->ArrayAccessMode, this->ArrayId, this->ArrayName, cellFlag);
  bool hasScalars = this->ScalarVisibility && (scalars != nullptr);
  bool hasPointScalars = hasScalars && !cellFlag;
  // Field data scalar mode treats field data like cell data
  bool hasCellScalars = hasScalars && (cellFlag == 1 || cellFlag == 2);

  bool usesPointNormals = polydata->GetPointData()->GetNormals() != nullptr;
  bool usesPointTexCoords = polydata->GetPointData()->GetTCoords() != nullptr;
  bool usesPointColorsWithTextureMaps =
    this->CanUseTextureMapForColoring(polydata) && hasPointScalars;
  bool usesPointColors = !usesPointColorsWithTextureMaps && hasPointScalars;
  bool usesCellColorTexture = !usesPointColorsWithTextureMaps && !usesPointColors && hasCellScalars;
  bool usesCellNormalTexture =
    !usesPointNormals && (polydata->GetCellData()->GetNormals() != nullptr);

  // The hash is seeded from the address of the lookup table.
  // WARNING: Technically, hash will overflow when
  //  &(lut) >= max_n_bit_ptr_address - 126, where n == 32 or n == 64
  MapperHashType hash = 0;
  // Get the lookup table.
  vtkDataArray* dataArray = vtkArrayDownCast<vtkDataArray>(scalars);
  vtkScalarsToColors* lut = nullptr;
  if (dataArray && dataArray->GetLookupTable())
  {
    lut = vtkScalarsToColors::SafeDownCast(dataArray->GetLookupTable());
  }
  else
  {
    lut = this->LookupTable;
  }
  hash = std::hash<MapperHashType>{}(reinterpret_cast<std::uintptr_t>(lut));
  hash += (usesPointColors << 1);
  hash += (usesPointNormals << 2);
  hash += (usesPointTexCoords << 3);
  hash += (usesPointColorsWithTextureMaps << 4);
  hash += (usesCellColorTexture << 5);
  hash += (usesCellNormalTexture << 6);
  return hash;
}

//------------------------------------------------------------------------------
void vtkOpenGLPolyDataMapper::BuildShaders(