Function vtkColorTransferFunctionMapData

Rendering/Core/vtkColorTransferFunction.cxx:1485–1524

// and unsigned short.
template <class T>
void vtkColorTransferFunctionMapData(vtkColorTransferFunction* self, T* input,
  unsigned char* output, int length, int inIncr, int outFormat, long)
{
  double x;
  int i = length;
  double rgb[3];
  unsigned char* optr = output;
  T* iptr = input;
  unsigned char alpha = static_cast<unsigned char>(self->GetAlpha() * 255.0);

  if (self->GetSize() == 0)
  {
    vtkGenericWarningMacro("Transfer Function Has No Points!");
    return;
  }

  while (--i >= 0)
  {
    x = static_cast<double>(*iptr);
    self->GetColor(x, rgb);

    if (outFormat == VTK_RGB || outFormat == VTK_RGBA)
    {
      *(optr++) = static_cast<unsigned char>(rgb[0] * 255.0 + 0.5);
      *(optr++) = static_cast<unsigned char>(rgb[1] * 255.0 + 0.5);
      *(optr++) = static_cast<unsigned char>(rgb[2] * 255.0 + 0.5);
    }
    else // LUMINANCE  use coeffs of (0.30  0.59  0.11)*255.0
    {
      *(optr++) =
        static_cast<unsigned char>(rgb[0] * 76.5 + rgb[1] * 150.45 + rgb[2] * 28.05 + 0.5);
    }

    if (outFormat == VTK_RGBA || outFormat == VTK_LUMINANCE_ALPHA)
    {
      *(optr++) = alpha;
    }
    iptr += inIncr;
  }
}

//------------------------------------------------------------------------------
// Special implementation for unsigned char input.