9.5.2

1006 • CHAPTER 19
TIMELINE • 1007
Figure 1: The thin line indicates left inuence.
So why would you want to switch off the spheres of inuence? By switching them off (i.e. by disabling
Left Inuence and Right Inuence), you can allow a track (or even an expression tag) of a lower priority
to take control over the parameter.
For example, suppose you want the robot to look at a space ship before and after the rotation
sequence. In other words, from frames 0 to 29, the robot will look at the space ship. From frames 30
to 60, the robot rotates its head as dened by the rotation sequence. Then from frame 61 onwards,
the robot once more looks at the space ship.
You can achieve this as follows. First you create a Target tag that points the robot’s head at the space
ship. You lower the priority of the Target tag (i.e. place it under the rotation track in the Timeline)
so that the rotation keys have priority (otherwise the tag’s expression would override the rotation
sequence and the robot would always look at the space ship).
This is where the spheres of inuence come into play. If Left Inuence and Right Inuence are enabled
for the rotation sequence, its inuence is extended to cover the entire animation and the Target tag
is not allowed to control the head during the empty regions. To allow the Target tag to control the
head’s rotation during the empty regions, Left Inuence and Right Inuence must be disabled.
To summarize, disable Left Inuence and Right Inuence if you want a track or tag expression of lower
priority to control the parameter during the empty regions.