Limbs

You can use a limb as an arm, leg, wing, and so on. Arms and legs are mostly similar in that they use the same IK system and have identical user interfaces.

• Select or add a hub object > Modify panel > Hub Setup rollout > Add Leg/Arm

There are two differences between legs and arms in CAT:

• Legs are assigned FootPlatforms, which include CAT's foot pivot system.
• Arms and legs are treated differently by CATMotion.

A limb can contain up to 20 bones, each of which can comprise up to 20 segments. Any limb can have a collarbone or palm, as appropriate.

You can set up limb bones in any configuration. IK setup involves simply rotating the bones in Setup mode.

Bone segments rotate only around the center of their bone. They allow for features such as twisting forearms. You control their relative rotations with the Bone Twist Weight graph (see Editing Limb Bones).

The Palm, which by default is automatically placed at the end of the arm, holds the arm controls for blending the arm between IK and FK. It also allows for the creation of an IK target for the arm, keying of all the rotations on a limb, and holds the main controls for the digits (fingers).

CAT supports seamless blending between IK and FK.

Each palm can have up to 100 digits and each digit up to 20 bones. Digits are set up with FK controls only. Digit controls include a weightable Digit Pose Manager and Digit modifiers for manipulating groups of digits.

The front leg of the Panther rig

Procedure

To add a limb:

1. Select a hub to which to attach the limb.
2. Do one of the following, depending on the type of limb to add:
   • To add an arm, do either of the following:
     • On the Modify panel Hub Setup rollout, click Add Arm.
     • In the viewport, right-click the hub and from the Tools 2 quadrant, choose Add Arm.
   • To add a leg, do either of the following:
     • On the Modify panel Hub Setup rollout, click Add Leg.
     • In the viewport, right-click the hub and from the Tools 2 quadrant, choose Add Leg.