Procedural animation is a form of art more than it is a form of technology. You assemble some powerful tools, but the way you use those tools is more like playing an instrument than it is like assembling a machine. The entire purpose of the tools is to provide lots of little knobs and buttons so that you can use your own aesthetic judgement, and understanding of human behavior/perception, to create a compelling illusion.
In the case of an “Eyeball with personality”, our goal will be to create the convincing illusion that there is a mind controlling the movement of the eyeball. Two things make this task easier than it might otherwise be: (1) We only need to move the eyeball along two axes (rotate in longitude, and rotate in latitude), and (2) We don’t need people to know what the eyeball is thinking — we need only convince them that it is thinking.
This last point is crucial, and it’s one of the things that makes procedural animation work. If you create a convincing illusion that there is a personality at work, people want to believe, and so they will suspend their disbelief. It’s the same thing that makes us care about Elizabeth Bennet and Mr. Darcy, even know we know full well that they exist only as words on paper.
In particular, we never quite know what Elizabeth Bennet will do next — Jane Austin builds a nice sense of unpredictability to this headstrong character. But it’s a controlled predictability — the character’s actions may be unexpected, but they take place within a set of constraints.
Going from Austin to Eyeball, tomorrow we will start with controlled randomness.