Kepler's Orrery

Kepler's Orrery is a gravity simulator that composes and plays
ambient music. In other words, it's a generative music system that uses gravity
equations as its driving force.

The physics: using basic Newtonian gravity equations and a 1st-order Euler
simulation, Kepler's Orrery solves n-body problems in a stepwise
fashion. Along the way it plays music while you fiddle with the
physics, build new worlds, and throw planets around to watch them bounce!

Each world, or planetary system, starts with its own initial
conditions, and then the planets and gravity wells attract each
other, swirl around, and collide according to the laws of
physics. The worlds are all different -- changing the initial
conditions a tiny bit makes the simulation come out differently.

Then there's the music: think of a system like a "song," which
changes with every different simulation. Whenever a body hits
something it plays the next note on its melody. Each system has a
different set of melodies that play on different instruments. Some
worlds make slow and ambient music; others are random, sharp, and
surprising.

You can play with the physics: change the gravitational constant; add
"antigravity" or friction; visualize the force fields and velocities.

Tilt the device, and the planets slide around in a virtual space
that's linked to our own "real" gravitational field.

You can also change the initial conditions of a world: with the world
editor, you can change the mass, positions and
velocities of the bodies and then restart the world to see how it
comes out different.

OSC: Kepler's Orrery sends its data about collisions and body
positions to other devices using the OSC (Open Sound Control)
protocol. And it's configurable.

更新履歴
Kepler's Orrery has a brand-new look! Now it's all planets and brushed
metal, and it works better -- lots of bugs have been fixed. Not to
mention all the new features: OSC, more interactivity, more worlds and
music.

OSC: Kepler's Orrery now sends its data out to other devices
using the Open Sound Control protocol, so you can control music,
lights, or whatever you want using a gravity simulation.

Interactivity: playing with gravity just got easier. You can see the
effects of planets you throw around; tilt gravity is now on by default
so you can play with the whole system by tilting your device to watch
the planets slide around in space.

More music: now with 30 worlds, Kepler's Orrery plays hours of ambient
generative music that comes out different each time. (Of course
there's yet another world named after one of the dogs, Kane). Switching worlds
and playing different songs is even easier, and you can control the
relative levels of background and collision music. There are new kinds
of music, e.g. planets that steal instruments, and now the volume of
notes depends on how fast the bodies collide.