Use controller-driven joints with pose space deformations

When you're working with character rigs, it's common for the joints to be driven by IK controllers or other rig controls to which they're constrained. Because you work directly with joints when you create pose interpolations, the Pose Editor won't recognize the joint as the driver of the poses if it's being controlled by another object. However, if you define the driving attributes of the controllers in the Pose Editor before you create poses, you can use pose interpolators with the controlled joints. This basically creates a connection mapping of which pose is driven by which attributes of which controller. The Pose Editor uses that mapping to make the proper connections and set the proper poses when double-clicking a pose or right-clicking it and choosing Go to Pose.

To define a controller's driving attributes for the joint

1. Select the character's controller-driven joint for which you want to create pose-interpolated shapes.
2. Open the Pose Editor and click the Create Pose Interpolator button.
3. A warning message appears telling you that the joint is being controlled by other attributes so you can't return to neutral poses if you create them at this stage: click No to not add neutral poses to the pose interpolator you're creating.

   The pose interpolator is created. Now you need to let the Pose Editor know which attributes of the controller are driving the joint's movement.

   Note: If you're working with a pose interpolator that already has neutral poses defined, delete them and continue with the following steps.
4. Right-click the pose interpolator and choose Show Driver Settings to display these settings below.
5. Add the controller's driving attributes to the driving joint's Controllers column in either of these ways:
   • In the Outliner, enable Display > Attributes (Channels) and expand the tree to show the controller's attributes. Then middle-drag the controller's driving attributes (such as Rotate X, Rotate Y, Rotate Z) one at a time to the Controllers column in the Driver Settings of the Pose Editor.
   • In the Controllers column in the Pose Editor, click Add. Middle-drag the controller's driving attributes (such as Rotate X, Rotate Y, Rotate Z) one at a time from the Outliner into the Driver Controllers window.

   An Edit button appears in the Controllers column. Click it to open the Driver Controllers window where you can add or remove driving attributes for the controller.

6. With the controller's attributes defined, you can now add the neutral poses to the pose interpolator: choose PosesAdd Neutral Poses or right-click in an empty area of the Pose panel (on the right) and choose Add Neutral Poses. This adds all three neutral poses: Swing & Twist, Swing, and Twist.
7. Start adding poses for the joint as you would normally. See Create pose space deformations for general workflow information.