Xform -rotateAxis problem

[project_68]

Hi.
Im trying to use the xform command to rotate the cv's of 1 curve about the position (and relitive to the tangent) of a corrisponding cv of another curve, slightly offset from the first.
in effect, this should allow me to corkscrew one curve based on another.
Problem is the rotate command only offers world or object relitive rotations.
the xform command seems to provide enough control, but in practice it just rotates about the world X axis along the origin instead of taking into account the -rotatePivot, and the -rotateAxis flags.
here is some code:

//calculate a usefull Parametric range for use as sammple points.
        float $cCSpans=getAttr ($cCshapeName[0] + ".spans");
                      float $paramStart=(1/($cCSpans+3));
                               float $paramEnd=(((1/($cCSpans+3))-$paramStart));

        for($i=$offSet; $i<(($cCSpans+3)-($offSet)); $i++)
        {
            if($tan)
            {
                //$paramStart=;
            }

            if($rotNum==$samples)
            {
            $rotNum=0;
            }

            //get the pos of the ref parameter
                float $refPos[]=xform -q -ws -t ($controlWire + ".cv[" + $i + "]");

            //get the tangent of the point, this will be the rotation axis
                float $tanPoint[]=pointOnCurve -turnOnPercentage 1 -t -pr ($paramStart * $i) $controlWire;
                string $wireShape[]=listRelatives -f -s $wire;
           // perform the rotation
                xform -r -ws -ro ($rot*$rotNum) 0.0 0.0 -rp $refPos[0] $refPos[1] $refPos[2] -ra $tanPoint[0] $tanPoint[1] $tanPoint[2] ($wireShape[0] + ".cv[" + $i + "]");
                $rotNum++;
        }

thanks!

[joojaa]

I have an alternate method. Extrude a circle along the curve then draw a curve on the tubes 2d underworld (aka curve on surface), if you manually type coordinates for the points you can wrap this curve several times achieving same thing.

Unfortunately i can not show you how to do this since i blew my graphics card answering your post the first time. ;(

[project_68]

Thx Joojaa!
Sorry to hear about your card:(
I get what you are saying adout curve on surface, however, I am trying to script a cable generation tool, which Im happy to share w/ you privatly so you can see whaat Im getting at.
the long and short is: I need to figure out how to use info derived from curveInfo -tangent and -normal and format that info to use as inputs into the xform -rotateAxis in order to rotate something from a given 3dpoint, around a given axis/vector.
I suppose I could just use a comparative distance between cv's and do the math to translate the cv into its proper position, but this seems terribly unelegant to me.
pm me if you want that script to peek at.
Thx again.
Scott

[joojaa]

See the reason is advised a alternate approach is that I was hoping you'd take a hint. The alternate approach is simpler, less code and faster and gives you a construction history, because thats how you use MEL. Now i have to explain for the millionth of time how maya does NOT work the way you think it does. If you want to approach this problem with this approach use the maya API its there for this purpose.

You can not use xform -rotateAxis the way you think becasue maya nodes are auxiliaries to specific nodes. xform is the auxilliary to the transformation node  it does not have much of a purpose outside manipulation of transforms. Granted maya abstracts selections as temporary transforms  but these transforms don't have ALL properties to transforms.

The bottom line is your solution needs to end up with a node of somekind, the less you sue time to manually manipulate things the better your nodes behave. Besides you get graphical user interfaces, build tools and user configuration for free when you use nodes.

Heres a very quick and dirty example i could do it much cleaner and make all transforms disappear into history but i have other things to do. Likewise i could eliminate twist problems on 3d curves but frankly so should you, again recurse as many times as you like.

{
$selection=`ls -sl`;
for ($item in  $selection){
$rebuld = `rebuildCurve -ch 1 -rpo 0 -rt 0 -end 1 -kr 2 
             -kcp 0 -kep 1 -kt 0 -s 50 -d 3
             $item`;
hide;
$twistSurf=`circle -c 0 0 0 -nr 0 1 0 
                   -sw 360 -r 1 -d 3 
                   -ut 0 -s 8 -ch 1`; 
hide;
$ext= `extrude -ch true -rn false -po 0 -et 2 -ucp 1 -fpt 1 
        -upn 1 -rotation 0 -scale 1 -rsp 1 $twistSurf[0] $rebuld[0]`;
hide;
$shape=`listRelatives -shapes $ext[0]`;
$maxV = `getAttr ($shape[0]+".sv")`;
print $maxV;
curveOnSurface -d 1 -uv 0 0 
                    -uv (12*8) ($maxV) -k 0 -k 1 $ext[0];
duplicateCurve;
}
};

pm me if you want that script to peek at.

Not really. If you want community support then you do it in the open. That is the proce of asking on a forum.

[project_68]

found a solution which involved more code than I had originally anticipated, and the performance is not as fast as I would have liked, but I took Jooja's hint (finally), and solved the problem by:
1. attaching a cluster to each cv of the curve that generated the tube extrude, and got the distance betw each cv.
2.placing an empty group under a locator node.
3. used a proc that aligns the locator (using the transformation matrix) to the tangent, normal and binomial at a given interval along the parametric length of the curve.
4. used a point constraint from the group node (under the locator) to the cluster[$c] and apply the desired rotation the group, thereby rotating the target curve CV about the U axis of the source curve at each parametric point required.

This allowed me to create a curve spiral of one curve about the U direction of a second curve.

Thx

S