How easy/hard would it be to use OpenGL for 2D graphics like you would use DirectX3D for 2D?

I'm considering making my feature 360<sup>o</sup> Space Shooter type game cross-platform compatable, with the option to use either OpenGL/AL or DirectX, but not sure if existing libraries will do that for me and how smooth a time durring development will I have.


Any ideas, hints or suggestions?