9.5.2

1050 • CHAPTER 21
ATTRIBUTE MANAGER • 1051
 In the Object manager, click the sphere’s name to select it and display its settings
in the Attribute manager.
 In the Attribute manager, right-click (Windows) or Command-click (Mac OS)
the P.Y box to access its context menu. From this menu, choose Animation >
Set Driver. (The P.Y box controls the sphere’s height, i.e. its Y position.)
 In the Object manager, click the cube’s name to select it and display its settings
in the Attribute manager.
 In the Attribute manager, right-click (Windows) or Command-click (Mac OS)
the P.Y box to access its context menu. From this menu, choose Animation >
Set Driven (Absolute).
 Move the sphere in the viewport.
The cube automatically moves to the height of the sphere. If you open the XPresso editor by double-
clicking the cube’s XPresso tag, you’ll see that three nodes have been created: Sphere, Range Mapper
and Cube. The Sphere node passes the sphere’s Y position to the Range Mapper, which, in this case,
simply passes the value straight on to the cube’s Y position. As a result, the cube continually inherits
the sphere’s height.
For this simple example, the Range Mapper has no signicance. However, the Range Mapper is useful
in cases where the relationship between the driver and driven parameter is not 1:1. For example, using
a Range Mapper, you can remap brightness values within the range 0-100% to position Y values within
the range 0-10,000 m. When the light’s Brightness is 80%, the Y position of the driven object will be
8,000 m (80% of 10,000 m). For more details on the Range Mapper node, look up ‘Range Mapper
node’ in the index.
Set driven keys also enable you to drive object parameters using your own sliders. To learn how to
create your own sliders, look up ‘User Data’ in the index.
Set Driven (Absolute), Set Driven (Relative)
With Absolute, the driven parameter uses exactly the same value as the driver. For example, if one
object drives the height of another, the driven object will move to exactly the same height as the
driver.
Relative, on the other hand, only passes on relative changes from the driver to the driven parameter.
For example, if the driver object is moved up 10 units in relative mode, the driven object also moves up
10 units from wherever it happens to be in the scene. Suppose the driver object has an initial height
of Y=1,000 and the driven object an initial height of Y=0. If you move the driver object to a height of
1,050 (a change of 50 units), the driven object also moves up 50 units, to Y=50.