The openGL code will most probably be written in C or C++, of which I have not heard anything about communicating with the serial port.
Both C and C++ support reading from and writing to the serial port. Not easily, but it can be done.
C# makes reading from, and writing to, the serial port trivial, AND can call openGL functions. I know, because I have a very fancy application that does just that, written in C#.