Seth Shafer’s Law of Fives (2015), for viola, bass clarinet, marimba, and computer, uses real-time notation and requires the performers to sight-read music as it is algorithmically generated during the performance. The piece is “cartographically” composed in the sense that the large-scale structure is mapped by the composer but the surface details are left to the computer and performers to determine. All material is based on a quintal (in contrast to duple or triple) rhythmic system: larger values are only divisible by five, which in turn are further divisible by five. Pitch material is based on an attractor system where two centricities trace independent arcing paths throughout the piece. The work exhibits five primary states of being that determine its overall form.
Microphones on the performers influence the system that generates the musical content displayed. The bach externals for Max handle the real-time notation display in the piece. Two bach.score objects occupy the performer interface. One bach.score shows the current notation being performed while the other shows what the performer will play next. In this way, the performer is always able to read ahead.
More about this project here.