Using TouchOSC to control Sonic Pi, with Processing as a bridge.

spi_osc_bridge.pde

// Passing on OSC data to Sonic Pi
import oscP5.*;
import netP5.*;

OscP5 oscP5;
NetAddress myBroadcastLocation; 

void setup() {
  background(0);
  frameRate(60);
  size (1,1); // We don’t need to see anything.
  oscP5 = new OscP5(this,12000); // The port to which TouchOSC or other OSC programs sends messages. 
  myBroadcastLocation = new NetAddress("127.0.0.1",4559); // The port on which Sonic Pi listens to incoming messages. 
}

void draw() {
}

void oscEvent(OscMessage theOscMessage) { // When you receive a message…
    oscP5.send(theOscMessage, myBroadcastLocation); // …just send it to Sonic Pi.
}

spi_touchosc.rb

set_sched_ahead_time! 0 # Setting that one to a negative value makes Sonic Pi complain, it sounds like.

with_fx :bpf do |s| # Setting up the fx to be controlled internally
  synth :blade, note: 32,release: 400 # Long release as the control will affect a single note
  live_loop :ctl do # The loop is inside the fx as this is where the action will be.
    ctl=sync "/accxyz" # The OSC message which Processing relays from TouchOSC's three-axes accelerometer. Sent from -1 to 1, so we need to get absolute values.
    rz=ctl[:args][0] # Assigning the x axis to resonance.
    ct=ctl[:args][1] # Assigning the y axis to centre frequency.
    mp=ctl[:args][2] # Assigning the z axis to amplitude.
    control s, res: (rz/2).abs, centre: (ct*100).abs, amp: mp.abs # The actual control of the fx.
    set_sched_ahead_time! -2
  end
end