llDetectedGrab() Example

I am trying to make a control panel for a device. One of the things I would like to make is a slider for a value to go between 1000 & 4000 very quickly. I assume llDetectedGrab() is the function to make this happen. But, I can't seem to grasp this one. Anyone have a little snippet showing how/when/what this function returns?

I would be interested in a good example of llDetectedGrab for something like this as well.

I got this to work on a single cylinder as a dial. But the only way I could get llDetectedGrab to work like this on an object was to turn physics on.

Then I can no longer make the "dial" turn independently if I try to link or joint it to a panel. With a link, it starts rotating the whole panel, not just the dial. And I could never get the joint to allow the dial to turn independently on its local z-axis.

And of course, even if I could get the dial to rotate on a joint hinge, I could not use that object as an attached HUD (can't use joints on an attatchement I guess).

So Question one:

Do I really need physics turned on in the object that is to be the dial (ie something that can be "turned" by llDetectedGrab)?

Is there a way to put a bunch of these dials onto a linked object so it can become a HUD attachement?

I also would appreciate any feedback on the code as to how I could do something better or if I am doing something silly. Its my first LSL program!

Here's the code I tried:

default
{
    state_entry()
    {
        // Could not get it to work at all without Physics on
        llSetStatus(STATUS_PHYSICS, TRUE);
        llWhisper(0, "Knob Activated");

        // Get and display the current z rotation as an integer
        // Get the current rotation of the Knob and convert to vector
        vector curEul = llRot2Euler(llGetLocalRot()) * RAD_TO_DEG;

        // Only care about the Z axis
        integer curVal = llRound(curEul.z);
        // For some reason the result of hte llGetLocalRot and the conversion
        // End up with a range of 0 to 180 then -180 to -1
        // So have to convert to 0 - 360 range
        if (curVal < 0)
        {
            curVal += 360;
        }
        // Display the current z value as hover text
        llSetText((string)curVal,<0,1,0>,1);        
    }

    touch(integer total_number)
    {
        // Get the value of the detected grab when touched
        // Probably should filter touches just for grabs
        vector grabVec = llDetectedGrab(0);
        // The value of the llDetected grab is usually less than 1
        // and I just need something to act as an increment / decrement value
        integer incVal = llRound(grabVec.x * 10); 

        // Get the current rotation
        vector curEul = llRot2Euler(llGetLocalRot()) * RAD_TO_DEG;
        // Convert to range of 0 - 360
        if (curEul.z < 0)
        {
            curEul.z += 360;
        }

        // Increment or dectrement the z axis value
        vector newEul = curEul + <0, 0, incVal>;
        // Convert it to an integer for display/use
        integer curVal = llRound(newEul.z);
        if (curVal < 0)
        {
            curVal = 0;
            newEul.z = 0;
        }
        if (curVal >= 360)
        {
            curVal = 360;
            newEul.z = 359.9;
        }
        // Set the new position
        llSetLocalRot(llEuler2Rot(newEul * DEG_TO_RAD));
        // Update the hover text
        llSetText((string)curVal,<0,1,0>,1);        
    }
}

I can't get in world atm, but from what I remember I think its relative to the local axis of the object not sure though.

A quick sample to debug would go something like this...

default
{
    touch(integer total_number)
    {
        if(llDetectedGrab(0) != ZERO_VECTOR)
        {
            llSay(0, (string)llDetectedGrab(0));
        }
    }
}