Combining 2 GOOD rotations makes a wrong one

Hello,

I am trying to make an eye-like object. It works very well on a single axis.

I made it work around the Z axis, it's great!
I made it work around the Y axis, it's great too!

but now, i wanted to combine these two rotations: my eye seems sick, it points to nowhere interesting, but it moves...

have a look at the script:

    vector eulbeta;
    vector eulgamma;
    
    // Here i compute BETA and gamma
    //...
 
    eulbeta= <0,beta,0>;
    eulgamma= <0,0,gamma>;

    quatbeta = llEuler2Rot(eulbeta); 
    quatgamma = llEuler2Rot(eulgamma); 
    
    quat =  quatbeta*quatgamma;  // This line does not work 
    // if i replace it by :  quat = quatbeta;   it works for one axis
    // if i replace it by :  quat = quatgamma;   it works for one axis
    
    llSetRot(quat); //rotate the object

Can you help me?

Thank you

how about q = llEuler2Rot( < 0, beta, gamma > );

I could have sworn that you divided rotations to combine them in SL (which is the opposite way the math is supposed to work). Since you're not working entirely within quaternion values, why not combine your rotations while they're assigned an euler value (Gamma+beta) and then apply the rotation.

To combine rotations you can multiply or divide. Multiply adds the rotations in the order of operations, dividing also adds them, but the divisors are done by rotating in the opposite direction.

That is, if you have a 1 R rotation and a .5 R rotation, 1*.5 rotates plus 1 radian, than plus .5 radians. 1/.5 first rotates plus 1 radian then minus .5 radians. (For clarity I'm only doing one axis)