Wrist bone twisting

A very common problem you might have with the rig is the exceptionally poor deformation of the wrist. While this can be fixed with shape keys, you may find that you are not able to use shape keys due to other limitations (pipeline, game engine, render engine, export/import restrictions, and so on). Figure 8.1 shows before and after adding a wrist twist:

Figure 8.1 – Wrist twist

In Figure 8.1, you can see that the top hand has terrible deformation at the wrist, while the bottom hand spreads the twist out along the forearm, just as our arms do.

The next screenshot shows how the bones are set up and the constraints used:

Figure 8.2 – Wrist twist setup

Let’s look at this in more detail.

The yellow bone is the IK target. The green bone is a new bone used for the wrist twist setup.

The green bone is parented to the forearm, with a Copy Rotation constraint targeting the hand at a...