I think I posted this to the wrong place earlier... this seems more relevant here.

I'm having a really painful time here... I'm making a 6 degrees of freedom shooter a la
Descent, and working out where to look at and in what direction to move depending on rotational orientation is just killing me. I'm not even sure anymore how rotational
orientation is to be stored... so far I'm just storing three angles (rotation around X, Y and Z) but I'm starting to wonder whether that's all that's needed. Assuming it is... I've managed to figure out that if it was a plain 3 DOF movement like in Doom, the four
directions of movement are simple sines or cosines of the angle of rotation. How do I
extend this to work with 6 degrees of freedom?? I'm stuck!!