Sfml Websites
OpenGL - Introduction
- open.gl
An extensive, yet beginner friendly guide to using modern OpenGL for game development on all major platforms.
Education For All
- sonarlearning.co.uk
Thousands of free video tutorials. Courses provided for programming, Maths, Science, History plus much more.
TGUI: Texus' Graphical User Interface
- tgui.eu
TGUI is an easy to use cross-platform c++ GUI library for SFML. The GUI library is available for Windows, Linux, Mac OS X, FreeBSD and experimentally supports Android, iOS and the Raspberry Pi.