Practical Algorithms for 3D Computer Graphics, 2nd Edition

192 6. Computer animation

1. The path taken by the object has abrupt changes of direction at a keyframe.

In some situations this might be desirable behavior but for most of the

time we would expect a simulation of realistic behavior to make the object

follow a smooth curve which pas s es through the points associated with the

keyframes.

2. Unles s the ratio of distance between keyframes to time interval between

keys is approximately constant in adjacent sections of the path, the ob-

ject will appear to move erratically and make abrupt changes of speed at

keyframes. In the example depicted by figure 6.1 it takes approximately

four times as long to cover ...