Physics
In the models that researchers have developed for simulation of articulated stick figures using such techniques as forward dynamics (Badler et al., 91), many realistic phenomena can be produced such as falling under gravity, bouncing collisions, and momentum and inertia effects. Many of these models are very robust, and sacrifice computational speed for simulation accuracy. The amount of detail in an implementation of a physics model should reflect the purpose of the research, or of the art, in some cases. I have constructed a qualitative physics model which works sufficiently for the general purposes of this research (dynamic design for visual communication and entertainment). It is simple yet it produces many of the salient features of interacting rigid bodies in the real world, such as gravitational effects, inertia, angular and translational momentum, friction, and dampening. Appendix B offers a more detailed description of the physics model developed for these figures.
This abbreviated physics model also does not place a burden on computation and thus is very fast for the purposes of real-time animation. As many as twelve of the Vertebrates can be animated at the same time on the screen at animation rates of more than ten frames per second. The ability to animate in real time or near real time is crucial for the interactive evolution aspect of this system to work - the user must experience true motion in each of the figures in order to do any comparative evaluation of subtle motion styles.
ARCHITECTURE
