
202 6. Computer animation
pointing interactively. In this case the keyframe could record an orientation as
a matrix or possib ly even as a quaternion directly; there is no need to use Euler
angles. The visual feedback from a refreshed display of the object is usually
sufficient for the animator to decide that the orientation they require has been
adopted.
6.2.4 Hierarchical animation
Hierarchical animation occurs when the action of one element is specified rela-
tive to the action of another element. The simplest example of an hierarchical
animation is for one model to follow another . Using recursive calls, very little
programming effort is required to