Bob Your Head to the Beat

At the IDC, the beat of the music drove a lot of the animation, supplementing the controls of the players. Bobbing heads and throbbing cameras were timed to the beat.

The beat came into Houdini's CHOPs through MIDI events from the master computer that timed the musical events. The most useful form of the musical beat was a ramp that rose from 0 at the start of a bar (4 beats) to 1 at the end of the bar.

From this ramp, many movements can be easily timed. And from this ramp, it is easy to get other ramps: every half beat, every 2 beats, every 8 beats, and so on. By making all these ramps available to the animator, they could easily choose and switch which ramp they wanted their animation to coordinate with.

Once a ramp is chosen, a lookup CHOP is often used to speed or slow a pre-keyframed move so it matches the beat. This is an important, simple control in synchronizing music and live 3D visuals.