This is basically related to my last topic, but I've narrowed down what exactly I don't know how to do.

Basically, I've figured out how rotation in Torque works now (more or less) but the vector math is still giving me loads of stuff. I can rotate vectors around axes of my choice, but I need to know those axes. Specifically, I need a way to get vectors that are perpendicular to the muzzlevector; the horizontal perpendicular should run parallel to the ground plane, while the vertical perpendicular should be perpendicular to both the muzzlevector and the horizontal perpendicular.

I have no clue how to do this. Can anyone help?