in a modelling program i use for architecture, there is this thing that has been buggin around my backhead for some time...

having an object and wanting to rotate it 2pi around z axis and pi around axis orthogonal to z, one stumbles upon a problem of Gimbal lock. that means that the software is counting it in such a way that for certain values the inerpolation collapses, because the interpolated values can cancel out at certain points. (there is quite a lot of info on GimblaLock through google so i don't explain it here)

to avoid this GimbalLock that results from expressing rotations in Euler algorithm, this software, as well many other graphic engines, allows the use of quaternions for rotations.

each quaternion is considered as an axis (of rotation) plus value of rotation. (3 imaginaries give axis, 1 scalar the value,amount of rotation)

multiplying by a quaternion rotates.

this software wants quaternions in normalized form - unit quats.

unfortunatelly, there is no good(readable) help coming with the script.

my question is this:

does anyone here use quaternions to note rotations, and if so, how would one note the above mentioned 1/2 spin ? (360around z & 180 around x, or y) ?