"Spawning" and "TSpawning"

In SC2, Spawn and TSpawn were two of the most powerful and commonly used UGens. In SC3 the idea of a top level Synth in which everything is spawned is no longer valid. Synthesis is always running (at least as long as a server is) and new Synths can be created on the fly. This arrangement results in even greater flexibility than in SC2, but requires a slightly different approach.

In SC3 one can create Synths at any time simply by executing blocks of code.

// do this

(

x = SynthDef("Help-SynthDef",

{ arg out=0;

Out.ar(out, PinkNoise.ar(0.1))

}).play; // SynthDef-play returns a Synth object.

)

// then do this

(

SynthDef("help-Rand", { arg out=0;

Out.ar(out,

FSinOsc.ar(

Rand(200.0, 400.0), // frequency between 200 and 400 Hz

0, Line.kr(0.2, 0, 1,

doneAction:2)) // frees itself

)

}).play(s);

)

x.free;

Clocks, such as SystemClock, provide a way to schedule things at arbitrary points in the future. This is similar to Synth.sched in SC2.

(

SystemClock.sched(2.0,{

"2.0 seconds later".postln; // this could be any code, including Synth creation

nil // this means don't repeat

});

)

In SC3 time-based sequences of events can be implemented using Routines. A Routine which yields a number can be scheduled using a clock:

(

var w, r;

w = GUI.window.new("trem", Rect(512, 256, 360, 130));

w.front;

r = Routine({ arg time;

60.do({ arg i;

0.05.yield; // wait for 0.05 seconds

{

w.bounds = w.bounds.moveBy(10.rand2, 10.rand2);

w.alpha = cos(i*0.1pi)*0.5+0.5;

}.defer;

});

1.yield; // wait for 1 second before closing w

w.close;

});

SystemClock.play(r);

)

Note that this implementation avoids one of the stranger aspects of the SC2 approach: The need to start a Synth to schedule time-based behavior, even if no audio is involved.

Both SystemClock and AppClock (a less accurate version which can call Cocoa primitives) have only class methods. Thus one does not create instances of them. If you need to have an individual clock to manipulate (for instance to manipulate the tempi of different sequences of events) you can use TempoClock.

A simple SC2 Spawn example is shown below, followed by its translation into SC3 style code.

// This will not execute in SC3

(

Synth.play({

Spawn.ar({

EnvGen.ar(Env.perc) * SinOsc.ar(440,0,0.1)

},

1, // one channels

1) // new event every second

}))

// The same example in SC3 (will execute)

s = Server.default;

s.boot;

(

SynthDef("help-EnvGen",{ arg out=0;

Out.ar(out,

EnvGen.kr(Env.perc,1.0,doneAction: 2)

* SinOsc.ar(440,0,0.1)

)

}).send(s);

)

(

r = Routine.new({ { Synth.new("help-EnvGen"); 1.yield; }.loop }); // loop every one second

SystemClock.play(r);

)

Note that the above example uses a precompiled SynthDef. This results in a lower CPU spike when Synths are created than SC2-style Spawning. It is possible to create SynthDefs on the fly, if this is necessary, but a great deal of variation can be achieved with arguments, or with ugens such as Rand and TRand. See the helpfile SynthDefsVsSynths for more detail.

// SynthDefs on the fly

s = Server.default;

s.boot;

(

t = TempoClock.new;

r = Routine.new({

10.do({

// could be done with an argument instead of a new def, but proves the point

SynthDef("help-EnvGen" ++ i,{ arg out=0;

Out.ar(out,

EnvGen.kr(Env.perc,1.0,doneAction: 2)

* SinOsc.ar(100 + (100 * t.elapsedBeats),0,0.1)

)

}).play(s);

1.yield;

});

}).play(t); // Note the alternative syntax: Routine.play(aClock)

)

Note the alternative syntax for playing a Routine. aClock.play(aRoutine) and aRoutine.play(aClock) are functionally equivalent. The two make different things more or less convienent, like sending messages to the Routine or Clock. (See the play helpfile for a more detailed discussion.) For instance:

(

// this, that and the other

r = Routine.new({var i = 0; { ("this: " ++ i).postln; i = i + 1; 1.yield; }.loop });

q = Routine.new({var i = 0; { ("that: " ++ i).postln; i = i + 1; 1.yield; }.loop });

t = Routine.new({var i = 0; { ("the other: " ++ i).postln; i = i + 1; 1.yield; }.loop });

)

SystemClock.play(r); // start this

SystemClock.play(q); // start that

SystemClock.play(t); // start the other

r.stop; // stop this but not that or the other

q.reset; // reset that while playing

c = TempoClock.new; // make a TempoClock

r.reset; // have to reset this because it's stopped

c.play(r); // play this in the new clock; starts from the beginning

c.tempo = 16; // increase the tempo of this

SystemClock.clear; // clear EVERYTHING scheduled in the SystemClock; so that and the other

// but not this

c.clear; // clear everything scheduled in c, i.e. this

c.play(r); // since it wasn't stopped, we don't have to reset this

// and it picks up where it left off

c.stop // stop c, destroy its scheduler, and release its OS thread

For convenience pauseable scheduling can be implemented with a Task. Task.new takes two arguments, a function and a clock, and creates it's own Routine. If you don't specify a clock, it will create a TempoClock for you. Since you don't have to explicitly create a Clock or Routine, use of Task can result in code that is a little more compact.

(

t = Task.new({

inf.do({ arg i;

i.postln;

0.5.wait

});

});

)

t.start; // Start it

t.stop; // Stop it

t.start; // Start again from the beginning

t.reset; // Reset on the fly

t.stop; // Stop again

t.resume; // Restart from where you left off

t.clock.tempo = 0.25; // Get the Task's clock and change the tempo. This works since the

// default is a TempoClock.

t.pause; // Same as t.stop

TSpawn's functionality can be replicated with SendTrig and OSCresponder or OSCresponderNode. See their individual helpfiles for details on their arguments and functionality.

s = Server.default;

s.boot;

(

// this Synth will send a trigger to the client app

SynthDef("help-SendTrig",{

SendTrig.kr(

Dust.kr(1.0), // trigger could be anything, e.g. Amplitude.kr(SoundIn.ar(0) > 0.5)

0,0.9

);

}).send(s);

)

(

// this recieves the trigger on the client side and 'Spawns' a new Synth on the server

OSCresponder(s.addr,'/tr',{

SynthDef("help-EnvGen",{ arg out=0;

Out.ar(out,

EnvGen.kr(Env.perc,1.0,doneAction: 2)

* SinOsc.ar(440,0,0.1)

)

}).play(s);

}).add;

// Start 'spawning'

Synth("help-SendTrig");

)