DirectX is not for graphics.
Direct3D is the
DirectX component for graphics. You can use
DirectX and
OpenGL together by using
DirectX for everything non-graphical and
OpenGL for the graphics.
People are often curious about whether Direct3D or OpenGL is better. They're both similarly functional and similarly fast, similarly easy, so really there's
no great difference between them.
However,Direct3D will only be available on
Windows platforms (Win2K, WinXP, XBox, etc.). And, OpenGL is avaliable
EVERYWHERE (all Windows platforms, Mac, Linux, Playstation, Wii, etc.).
So if you're only writing for Windows platforms, doesn't really matter which. Otherwise, go
OpenGL. Moreover,
OpenGL is easier for beginners and more portable.
For more information,visit
Comparison of OpenGL and Direct3D[
^]