8.2. Working with PyDrivers

Blender users who do character animation or other work that requires sophisticated, complex movements to be controlled in simple ways should already be aware of the power of Ipo drivers in general. If you have not worked with Ipo drivers, I recommend that you first read the chapter of my book Introducing Character Animation with Blender (Sybex, 2007) that deals with using Ipo drivers to set up poseable rigs. Even if you do not need this specifically for character work, you will find that any nontrivial rigging task will benefit from a knowledge of how to use Ipo drivers.

The way Ipo drivers work is to create a mapping from one value to another. For example, a bone's position within a given range might be used to control the influence of a shape key on the mesh, or its rotation might be used to drive a preanimated action. However, as powerful as Ipo drivers are, they are limited by this direct mapping between two values. If the relationship between the driver and the driven value cannot be represented by a single Ipo curve, it can't be encoded as an Ipo driver.