[Flere-Imsaho]

OpenGL (the main competition to DirectX) really wasn't that bad in the fixed-function days. Everything fell apart when nVidia / AMD came up with their own standards for GPU programming.

DirectX was nice in that the documentation, and example/sample code was excellent.

[sorenjan]

The fixed function version of OpenGL was non thread safe with global state, it made for some super fun bugs when different libraries set different flags and then assumed they knew which state the OpenGL runtime was in the next time they tried to render something.