[ODE] quat to eulerXYZ

[Patrick Enoch]

Hello all,


I am having problems with angular velocities. currently i am  
interfacing ODE to another program which uses eulerZXY.
so if i have a body with eulerZXY angular velocity, I need to convert  
it to ODEs eulerXYZ.
i am using quaternions as the interface, which looks like this:

prog eulerZXY at time A and B -> quats at time A and B -> ODE  
eulerXYZ at time A and B
(angular velocity is difference between eulers divided by (B-A))

BUT:
when converting quats -> eulerZXY there are jumps in the conversion.  
for example:

euler ZXY (0,89,0) -> eulerXYZ (89,0,0)  (works fine)
euler ZXY (0,91,0) -> eulerXYZ (180,-91,180) (pretty far away from  
the above)
(values as far as i remember. but i think the prob is clear. the  
difference should be small, but the resulting
angular velocity is very big. conversion depends on into which  
quadrant the rotation points, its an
unsteady function. )

anyone knows a quat -> euler converter, which i can tell to give me  
values "near" to another triple?


Patrick