Opengl Tutorials "3D Graphics Library"

OpenGL Programming Guide "RedBook" 
[PDF] http://madison-project.wikidot.com/local--files/tutorials/OpenGL_Programming_Guide.pdf 

OpenGL Reference Manual "BlueBook" 
[Pdf] http://madison-project.wikidot.com/local--files/tutorials/OpenGl_Reference_Manual.pdf 

GtkGLExt is an OpenGL extension to GTK+ 2.0 or later 
[HTML] http://www.k-3d.org/gtkglext/Main_Page <-- Download source for lots of C/Gtk+ example code. 

osgGtk is a library of C based Gtk+ and C++ based Gtk-- widgets to support OpenSceneGraph (OSG) applications. 
The library also includes several example applications such as osgviewerGtk and osgviewerGtkmm. 
[HTML] http://osggtk.wiki.sourceforge.net/main <--Download source for C/Gtk+ example code. 

source: http://www.gtkforums.com/about988.html