Look into :
C++:
www.fox-toolkit.org (specialized for opengl related apps)
C++:
www.trolltech.com (QT is only free for use if you gonna build open source applications)
A friend of mine uses the fox toolkit with great content. Docs are fairly good. Never got into Qt though, but if you wanna know how good Qt is, open up KDE and you are right in Qt's territory.
SDL is the open source alternative for directx , it uses opengl as graphical library.
Happy Coding
Greetz
Morrowyn