rotating a chair

so ive been trying to set a multiprim objects x and y rotations to 0, while leaving z alone
been unsuccessful so far, ive been in SL for 3 days, and have my vehicles half working...

ive tried all of these

//rotation rot = llGetRot();
//rot.x = 0;
//llSetRot(rot);
//llSetLocalRot(rot);

//list rot = llGetPrimitiveParams([PRIM_ROTATION]);
rotation rot = llGetRot();
//rotation rot = llGetLocalRot();
rot.x = 0;
rot.y = 0;
llSetPrimitiveParams([PRIM_ROTATION, rot]);
llSay(0,"rotation set";

i get the set msg, but rotation remains unchanged

does it not work because im sitting on it?
or what

update:

vector asd = <0,90,0>;
vector zxc = asd * DEG_TO_RAD;
qwe = llEuler2Rot(zxc);
}
touch_start(integer total_number)
{
llSetRot(llGetRot()*qwe);
//llSay(0,(string)llGetRot());
llWhisper(0,"touch rotation set";
}

doesnt work either,
get the msg, no rotation

Try this:

(Compiled and tested to some degree in-world.)

rotation levelRotation(rotation oldRot)
{
    vector xOld = llRot2Fwd(oldRot);
    vector yOld = llRot2Left(oldRot);
    
    vector xNew;
    vector yNew;
    if (1.0-llFabs(xOld.z) < 0.01)
    {
        xNew = llVecNorm(<yOld.y, -yOld.x, 0.0>);  // yOld % z
        yNew = <-xNew.y, xNew.x, 0.0>;  // z % xNew
    } else
    {
        yNew = llVecNorm(<-xOld.y, xOld.x, 0.0>);  // z % xOld
        xNew = <yNew.y, -yNew.x, 0.0>;  // yNew % z
    }
    
    return llAxes2Rot(xNew, yNew, <0.0, 0.0, 1.0>);
}

default
{
    touch_start(integer total_number)
    {
        llSetRot(levelRotation(llGetRot()));
    }
}

and also, how do radian degrees work?
why is there -4- variables?

not that im ever going to use it >_>


and also, my chair controls stop working once it leaves the ground, even if it lands again

Rotations in SL and many other computer 3d environments are calculated off of Quaternions which, while nifty are baffling to most without a degree in calculus.
http://en.wikipedia.org/wiki/Quaternion

A simple code snip shows how to do absolute rotations, handy for making objects face east, north, up, etc.

vector eul = <0,0,45>; //45 degrees around the z-axis, in Euler form
eul *= DEG_TO_RAD; //convert to radians
rotation quat = llEuler2Rot(eul); //convert to quaternion
llSetRot(quat); //rotate the object


Not sure what's wrong with your vehicle stopping to function after leaving the ground, I haven't done much (read: anything) with the actual vehicle code in SL, generally just rockets based on llApplyImpulse.

The radian is a unit of plane angle, equal to 180/pi degrees, or about 57.2958 degrees. Wikipedia has interesting articles about both Quaternion and Radian mathematics.

In particular, the following section is quite relevant and understandable in my opinion, and pertains directly to SL.

http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Parametrizing_the_space_of_rotations_with_quaternions

The only other thing you really have to understand is that multiplying a vector by a quaternion in LSL is the equivalent of the whole expression q*v*(q^-1); it performs the whole transformation, so you don't have to worry about all the mechanics underneath (all that extra stuff the article talks about after giving you the important formula involving sin(alpha/2) and cos(alpha/2) ).

In other words, the MOST you might want to know about quaternions to use them for rotation in SL is that:

rotation rot = llAxisAngle2Rot(axis, alpha);

// is equivalent to:

rot.x = axis.x*llSin(alpha/2);
rot.y = axis.y*llSin(alpha/2);
rot.z = axis.z*llSin(alpha/2);
rot.s = llCos(alpha/2);