I wrote about this last December: http://blog.richardkiss.com/?p=398 http://blog.richardkiss.com/?p=398 The matrix math is easier, and the Python code is abou

I wrote about this last December: http://blog.richardkiss.com/?p=398 http://blog.richardkiss.com/?p=398 The matrix math is easier, and the Python code is about a dozen lines.