Calculating local offset

morning,

I'm having trouble with rotations.

What I want to do is find the ground level at a point in the sim, relative to an object. That is:

vector A = llGetPos();
// the object has an random rotation
vector B = target_position;
integer C = llGround(vector D);

vector D is vector B in terms of A's position and rotation. How do I calculate vector D?

I know I have to perform the position transformation

vector E = B - A

I then have to take into account the rotation of the object

rotation AA = llGetRot()

At first, I thought I could do this

vector D = E * (-1 * AA)

But thats not right. I think I've missed a step out, but I cant figure out what.

Anyone help?
Thanks in advance.

llGround doesn't take into account rotations.

So this code should get you where you want to go:

groundAtPos(vector position) {
    return llGround(position - llGetPos();
}

The reason why it works, is that llGround takes an offset from your current position. This means the vector it works with internally already has llGetPos() added to it. To get a ground height at a specific position, you would subtract llGetPos from your position, because llGetPos is added later on.

(Sorry if this seems a bit off, 4 AM... can't tear myself away from SL )
==Chris

Thanks Chris,

Looks like I was trying to make it more complicated than needed to.

I shall l give your code a go.