Query last joint of ik chain?

[jessec]

Hey. I need to find out what the name of the last joint is that an ikHandle is controlling. Well, it's the joint where the end effector is placed at.

I know I can find the first joint that the chain is controlling like this:

In reply to:string $startJoint[] = listConnections -d off -s on ($ikName + ".startJoint");

...But I can't seem to find the endJoint this way. Nor by querying any of the ikHandle related commands either. Anyone have a clue how to find out the name of this last joint in the IK chain???

[failure]

ikHandle -q -jl ikHandle1;

[jessec]

Yeahhhhh...

That's one of the ones I tried but it wouldn't work.

For example, I'm working on my left leg IK setup... It starts at the hip, and goes down to the ankle. When I query the jointList, it only returns the "L_Hip" and "L_Knee" joints, as those are the only joints being solved for. I need to have "L_Ankle" returned to me some how as well.

[jessec]

Hmm, I can't query the effector command (for an endEffector) to find what joint it's applied to either.

The only way I can think of so far is to use the ikHandle query, select the second listed joint, and then pickwalk down one to the ankle joint.

I'd thought of this before, but I didn't want to take the chance of having something else parented beneath this knee joint possibly being selected instead though. It would be nice to have the actual certain name of this joint returned instead.

[failure]

The joint you want to get is not really a part of the ik chain. Anyway, query the joint list with ikHandle command and then get the child of last joint in the list with:

listRelatives -children -type joint lastJointName

[queequeg]

You can also use
ikHandle -q -endEffector
When Maya sets up the IK chain, the translate attribute of what you refer to as the last joint in the chain is connected to the effector's translate. So you can use listConnections on the effector's translate.

[failure]

Even better. Just have in mind that this connection happens by default but is not guaranteed to be there in every case. There are some rigging situations which have effector at different place, thus the translate connection is broken.

[jessec]

Ahhh yeah, like if you have forearm joints. Thanks for the tip!

I'm almosstttt done. One last problem, maybe other people have had the same one... But I have lined up my pole vector constraint object with the ikHandle's pole vector, so it shouldn't move the joint chain at all when I actually create the PV constraint...

However, whenever I go to create this constraint, the target object I'm constraining the pole vecotr to, MOVES, causing the entire joint chain to move and point in this new direction. Anyone know what

[jessec]

Ok, if anyone has the time, can you check out my script and see what's up with the very last step of applying the pole vector constraint???

In reply to:// The following procedure is still under construction, but it is designed to automatically
// create a leg IK knee direction control, with a controlling attribute added to a nurbs
// foot control.
proc createCircles(string $name)
{
// Create 3 circles, which each decreasing in size from the previous:
circle -c 0 0 0
-nr 1 0 0
-sw 360
-r 1
-d 3
-ut 0
-tol 0.01
-s 6
-ch 1
-name ($name + "_Constrain");
string $circle1 = $name + "_Constrain";
circle -c 0 0 0
-nr 1 0 0
-sw 360
-r .75
-d 3
-ut 0
-tol 0.01
-s 6
-ch 1
-name ($name + "_Rotate");
string $circle2 = $name + "_Rotate";
circle -c 0 0 0
-nr 1 0 0
-sw 360
-r .5
-d 3
-ut 0
-tol 0.01
-s 6
-ch 1
-name ($name + "_pVector");
string $circle3 = $name + "_pVector";
// Parent the circles:
parent $circle2 $circle1;
parent $circle3 $circle2;
}

// Procedure lineUpPoleVector will line up a pole vector control object with an ikRPsolver IK chain so that it does not
// offset or rotate your original joints at all.
// This procedure must start out with your pole vector object point constrained to the joint at the top of the
// IK hierarchy, with it's transformations froozen.
proc lineUpPoleVector(string $ikName, string $circle1, string $circle3)
{
// Find joint at top of IK chain:
string $sJoint[] = listConnections -d off -s on ($ikName + ".startJoint");
string $startJoint = $sJoint[0];
string $eJoint[] = ikHandle -q -jl $ikName;
select -r $eJoint[size $eJoint - 1];
string $EJoint[] = pickWalk -d down;
string $endJoint = $EJoint[0];
select -cl;
// Constrain control curve to top & bottom joints of the IK chain, orientConstraint it to the top joint:
pointConstraint -w .1 $startJoint $endJoint $circle1;
orientConstraint -skip y $startJoint $circle1;
// Constrain pVector circle to top ikJoint, delete constraint, and freeze transforms:
pointConstraint $startJoint $circle3;
pointConstraint -e -rm $startJoint $circle3;
makeIdentity -apply true -t 1 -r 0 -s 0 -n 0 $circle3;
// Get attributes to use from the IK handle's pole vector settings and multiply by 10 to give a useful offset:
float $Xval = (getAttr ($ikName + ".poleVectorX") * 10);
float $Yval = (getAttr ($ikName + ".poleVectorY") * 10);
float $Zval = (getAttr ($ikName + ".poleVectorZ") * 10);
// Move pVector circle into place to line up with the IK's Pole Vector:
xform -r -t $Xval $Yval $Zval $circle3;
}

global proc ikRotateSetup()
{
// Get selection and check for errors:
string $selection[] = ls -sl;
if (size $selection == 0)
error ("Please select a control curve and then an IK handle.");
if (nodeType $selection[0] != "transform")
error ("Please select your control shape first, then the IK handle.");
if (nodeType $selection[1] != "ikHandle")
error ("Please select an IK handle after your control shape.");
if (size $selection > 2)
error ("Please select a control shape and then an IK handle.");
if (size $selection == 0)
error ("Please select a control shape and then an IK handle.");
string $ikName = $selection[1];
string $circName = $ikName + "_circ";
// Create and name 3 circles, grouped under each other.
createCircles($circName);
string $circle1 = $circName + "_Constrain";
string $circle2 = $circName + "_Rotate";
string $circle3 = $circName + "_pVector";
select -r $circle1;
lineUpPoleVector($ikName, $circle1, $circle3);
}

You can copy this and paste it into your script editor, execute it, and then just simply select your hand/foot control first, and then the ikHandle for your leg/arm, then run "ikRotateSetup();" in the script editor, without the quotes. From here, you should just simply have select the smallest circle, and then the ik handle and do a pole vector constraint, but you should see what I talk about, as this is where the small circle changes it's position completely and causes the joint chain to move with it as well. :-S

[jessec]

Oh...

I can just connect the IK "twist" attribute and do the same thing. Oops.

Hmm, I knew about that attribute, but I just figured there had to be some kind of benefit to doing this the hardest way possible. Doh.