what am i missing ?

hello
this plays an animation when you sit on it
problem is the height detection, it works but only when you stand up and sit again
and not for the first time, i dont know what am i missing?
it says the correct vector everytime

default 
{
    state_entry() 
    {
        if (llStringLength(SIT_TEXT)>0)
            llSetSitText(SIT_TEXT);
            set_text();
    }

    
    changed(integer change) 
    { 
        if (change & CHANGED_LINK) 
        {
            
            if (llAvatarOnSitTarget() != NULL_KEY) 
            { 
                {
                avatar = llAvatarOnSitTarget();
                size   = llGetAgentSize( avatar ); 
                height = size.z - 1;
                } 
                llSay( 0, "vector " + (string)height);
                vector POSITION=<0.0, 0.15, height>;
                llSitTarget(POSITION, ZERO_ROTATION);
                llRequestPermissions(llAvatarOnSitTarget(), PERMISSION_TRIGGER_ANIMATION);
            }
            else
            {
                integer perm=llGetPermissions();
                if ((perm & PERMISSION_TRIGGER_ANIMATION) && llStringLength(animation)>0)       
                llStopAnimation(animation);
                llTargetOmega(<0.,0.,0.>,PI,1.0);
                set_text();
                animation="";
            }
        }
    }

run_time_permissions(integer perm)
    {
        if (perm & PERMISSION_TRIGGER_ANIMATION)
        {
                llStopAnimation("sit");
                animation=llGetInventoryName(INVENTORY_ANIMATION,0);
                llStartAnimation(animation);
                llTargetOmega(<0,0,0.3>,PI,1.0);
                llSetText("",<0,0,0>,0.0);
        }
    }
}

also the rotation will rotate the world rather then the table for the person who sits on it
how can i fix this?

thanks for your time

It is because you have already sat on the prim when you set the sit target, so its using the old value.

oh duh now i see it, thanks for the hint

i have moved the height detection ouf of the changed_link event
but now im missing a trigger i dont wont to have to touch it or have repeat sensors
how can i trigger something when someone sits on it but before he sits ?

thx

As far as I know you can't. The way a sit works prevents it. The sit target is set before the sit and the simulator makes the AV sit on the target when they select sit from the menu. I don't think you can get any info about the sit till it is over.

Bad is correct, its a chicken and egg situation.

One option is to move the sit ball after they sit.