Audiovisuals with SC - Example03b - louder is darker

//Example03b - louder is darker
//only one line differs from Example02a. the one in the main loop where we invert the mapping.
(
s.latency= 0.05;
s.waitForBoot{

//--window setup
var width= 640, height= 480;
var w= Window("Example03b - louder is darker", Rect(99, 99, width, height), false);
var u= UserView(w, Rect(0, 0, width, height));

//--variables
var pat= Pn(Pshuf(#[0, 0, 0, 0, 0.1, 0.25, 0.5, 0.75, 1, 1], 8), inf).asStream;
var syn= SynthDef(\av, {|amp= 0|
var z= LPF.ar(LFSaw.ar(#[300, 301, 80, 81], 0, amp).mean, 2000);
Out.ar(0, Pan2.ar(z));
}, #[0.05]).play(s); //short lag time to avoid clipping
var amp= 1;

//--interface
~radius= 100;
~fps= 10;

//--main loop
u.drawFunc= {
if(u.frame%(~fps/60).reciprocal==0, {
amp= pat.next; //get the next value from the stream
syn.set(\amp, amp); //send to the synth
amp= 1-amp; //here we invert the mapping
});
Pen.translate(width*0.5, height*0.5); //offset drawing to the centre
Pen.fillColor= Color.grey(amp); //fill with color corresponding to amp
Pen.fillOval(Rect.aboutPoint(Point(0, 0), ~radius, ~radius));
};

//--window management
u.clearOnRefresh= true;
u.background= Color.grey(0.5); //keep neutral background
w.onClose= {syn.free};
w.front;
u.animate= true;
CmdPeriod.doOnce({if(w.isClosed.not, {w.close})});
};
)

//change these while the program is running
~radius= 200;
~radius= 300;
~fps= 30;
~fps= 15;
~fps= 5;
~radius= 15;

//close the window to stop or press cmd+.