I was in same boat as you many years ago, now I work in game industry. Because 3D graphics have advanced so much in the last decade, the old route of just learning basic OpenGL or DirectX is going to be very difficult. I would recommend first leaning how the artists create the 3D then move into OpenGL and DirectX. Best way to do this right now and get most bang for your buck is to download the free Unreal Dev Kit, and get a decent book on Amazon for it. Try to make a 3D scene with some models and animation and really learn how that works, then move onto the deep down stuff in OpenGL.