rotate to line up with arbitrary vector.

[khonsuu]

I have an arbitrary unit vector and an object with zero rotation.  I want to rotate this object so that its negative X axis (X-)  lines up with the unit vector.  What is the script  to perform this?

 

I have an object which is currently at rotation =<0,0,0>  in its edit tabs.  Inside of the object's script is an arbitrary unit vector called Nface.  I would like to perform llSetRot() or similar in a script to make it line up with Nface.  That is , I want the object's  negative X-axis  to line up with Nface via a rotation.  What would be the code for this?

For ease of coding, it is possible to instead reverse Nface and then make the positve X-axis  (X+)  line up with it.  This might make the code significantly easier. (just a thought).

[Xiija]

       vector pos = llGetPos();
       vector Target = Nface;
       llRotLookAt( llRotBetween( <-1.0, 0.0, 0.0>, llVecNorm( <Target.x, Target.y, pos.z> - pos ) )  , 1.0, 0.5 );

// choose which face to use with <-1.0, 0.0, 0.0> (this is negative x)

//                                                           <0.0, 1.0, 0.0> (this is positive y)

[khonsuu]

Dear Xiija,

Thanks for the reply. You helped to point me in the right direction. (insert dry pun)

It seems the command I needed was something more like ths.

llRotLookAt(    llRotBetween(<-1.0, 0.0, 0.0>,  Nface),    1.0,      0.4);

[Rolig Loon]

Yes, that will work.  Typically, though, it's wise to look at the angle between <-1.0,0.0,0.0> and llVecNorm(Nface), because llVecNorm normalizes the target vector, thus scaling it to the same magnitude as your start vector.  It makes for neater math.