Discussion: Alternative to llLookAt using llSetRot

For some applications llLookAt doesn't function like it should, for example a HUD attachment that's supposed to point at a specific spot, or if for some strange reason you wanted your prim to look along a unit vector. What I have done here is reconstructed the llLookAt function using llSetRot. I used global coordinates so that if it's a fixed point, it will work across sim borders. the vector lookat is where the object will point to (in global coordinates). the prim points along it's Z axis, but you could easily change it so that it pointed along it's x or y axis by changing the <0,0,1> vector in the llGetRotBetween command to the appropriate unit vector.

*how it works*
very simple really, it takes your position (or the prims) and the coordinates of where it's supposed to be looking at and creates a vector between them. then it uses the llGetRotBetween to get a rotatation between the z axis and where you want to look at and then applies that rotation to the llSetRot command.

Of note is the llSetRot command itself; there is a divisor in there. this is because I'm assuming it's an attachment and it corrects for the avatar's orientation. if this is going to be put in a object that's not attached to an avatar, then the line should be :

llSetRot(rotvec);

if you leave it "as is" in an unattached prim your pointer will dance

vector lookat = <0,0,0>; //this is where the item will look at. remember to add +llGetRegionCorner() to the coordinates if they're taken from a sensor.

default {
    
    state_entry() {

                        llSetTimerEvent(.01);//because llSetRot is not "autoupdating" like llLookAt(), we need to constantly update where it's looking to.

    
            }

    timer()
    {
vector gposition = ( llGetRegionCorner()+llGetPos() ); //global position of the prim.
vector target = (lookat - gposition); // A vector to rotate along. "lookat" is where it's going to look at in global coordinates.
rotation rotvec = llRotBetween(<0,0,1>,llVecNorm(target)); //the rotation quaternion to rotate our object from pointing "up" towards the vector pointing at the waypoint
                                llSetRot(rotvec/llGetRot());

}
}