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Wrist Rig

Let's take a moment to consider what we're going to do with the wrist. You could place a gyro at the wrist, and use it to rotate the hand (palm bone) in any direction. It would also be handy to be able to move the wrist control and have it move the hand and bend the arm.

To make this happen, you can place the gyro at the wrist and link the IK chain to the gyro. So far, so good. But to make the palm rotate with the wrist control, you'd want to link the palm bone to the control object, too.

However, this would create a problem. The palm is part of the IK chain, so you can't link it to another object without breaking the chain. If you break the chain, the arm won't work any more.

To solve this problem, you'll use an orientation constraint to make the palm's rotation always match the wrist control. This is a type of controller that forces one object's rotation to always match another's. An orientation constraint is a useful alternative to linking, especially when linking isn't possible.

To make the wrist rotation work intuitively with the orientation constraint, you'll need to align the orientation of the control shape's pivot point with the palm bone's pivot point. There's no need to align the pivot point alone; you can simply align the entire object. This is because a gyro looks the same no matter which way it's oriented.

At this point, you've learned enough to complete the rest of the rig. I'll walk you through the process, but I won't give as much detail in the steps as I did before. Let's see if you can do it!

TUTORIAL R10: Rigging the Wrist

The rig for the hands requires a little more work, but uses principles you've learned already.

Prepare the Scene
1.
Load the file CharRig12.max that you created earlier, or from the Rigs folder on the CD.

2.
Unhide all the bones.

3.
Hide the spine controls. You won't need them for a while, and they'll only get in the way.

TIP

To quickly unhide all the bones, you can choose the Bones selection set that you created earlier. When asked if you want to unhide the objects, answer Yes.


Create the Wrist Control

You'll use an IK solver to rig the upper and lower arms.

1.
Select BoneUpperArmL, the left upper arm bone. Choose Animation > IK Solvers > HI Solver, and click the palm bone to create an HI Solver for the left arm.

2.
Name the new IK chain IKWristL.

If you like, you can move the IK chain around a little to ensure the palm is moving along with it. Undo any movements before continuing.

3.
Choose File > Merge, and open the file ControlShapes.max in the Rigs folder on the CD. Merge the object Gyro from the file.

This is the shape made from three circles.

4.
Name the gyro CtrlWristL.

5.
Align the position of CtrlWristL with IKWristL.

Assign the Orientation Constraint
1.
Align the orientation of CtrlWristL to BonePalmL.

This will rotate CtrlWristL so its pivot point has the same orientation as BonePalmL's pivot point.

2.
Select BonePalmL.

3.
Choose Animation > Constraints > Orientation Constraint, and click CtrlWristL.

4.
Test the constraint by rotating CtrlWristL. The palm should rotate in the same direction as the control shape.

Complete the Wrist Rig
1.
Link the IK chain IKWristL to CtrlWristL.

2.
Test the rig by moving CtrlWristL.

The arm and hand should move together, and the elbow should bend. Undo any movements before continuing.

3.
Save the scene as CharRig13.max.

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