//SLUGens released under the GNU GPL as extensions for SuperCollider 3, by Nick Collins, http://composerprogrammer.com/index.html
Fixed masses apply Newtonian gravitational force dynamics to a central moving mass which cannot escape the [-1, 1] grid in x or y. The position of the moving mass is sonified as an oscillator by its distance from the centre.
This is a relatively expensive oscillator to run.
Restart the moving mass at a random position within the square (k-rate input)
amount of position update per sample (k-rate)
kr input to be sampled for new x positions for the moving mass on reset
kr input to be sampled for new y positions for the moving mass on reset
Bufnum for a buffer containing weights and positions for the fixed influencing masses. In the format entry  is the number of masses, then 3 components (x, y, mass multiplier) for each mass in turn (see below). You can dynamically change this buffer as long as the data contents stay consistent- i.e. if you change suddenly to having twice as many masses, make sure you've provided x,y and weight values for them!