I\'m starting a hobby game project on Windows that will make heavy use of 3D graphics effects. It will most likely be written in C++.
Should I use OpenGL or Direct3D for
If you're willing to consider C#, take a good look at XNA. For hobby projects, assuming what you want is to actually get a game up and running instead of tinkering with complex API code, I cannot recommend it highly enough. It is increasingly mature, well-documented, and, compared to D3D/OpenGL, very quick and easy to use. As a bonus, with a $100/year Creators Club membership, you can even use it to develop games for the Xbox 360.