rsc3/doc-schelp/HelpSource/Classes/Gendy2.scrbl

#lang scribble/manual
@(require (for-label racket))

@title{Gendy2}
 Dynamic stochastic synthesis generator.@section{related}
  Classes/Gendy1, Classes/Gendy3
@section{categories}
   UGens>Generators>Stochastic


@section{description}


See  link::Classes/Gendy1::  help file for background. This variant of
GENDYN is closer to that presented in emphasis::Hoffmann, Peter. (2000) The New GENDYN Program. Computer Music Journal 24:2, pp 31-38::.

@section{note}
 
Random walk is of the amplitude and time delta, not the amp and time
directly. The amplitude step random walk uses a Lehmer style number
generator whose parameters are accessible.
::

SuperCollider implementation by Nick Collins

@section{classmethods}
 

@section{method}
 ar, kr


@section{argument}
 ampdist

Choice of probability distribution for the next perturbation of
the amplitude of a control point.

The distributions are (adapted from the GENDYN program in Formalized Music):
@section{table}
 
## 0: || LINEAR.
## 1: || CAUCHY.
## 2: || LOGIST.
## 3: || HYPERBCOS.
## 4: || ARCSINE.
## 5: || EXPON.
## 6: || SINUS.
::

Where the sinus (Xenakis' name) is in this implementation taken
as sampling from a third party oscillator. See example below.

@section{argument}
 durdist

Choice of distribution for the perturbation of the current inter
control point duration.

@section{argument}
 adparam

A parameter for the shape of the amplitude probability
distribution, requires values in the range 0.0001 to 1 (there are
safety checks in the code so don't worry too much if you want to
modulate!).

@section{argument}
 ddparam

A parameter for the shape of the duration probability
distribution, requires values in the range 0.0001 to 1.


@section{argument}
 minfreq

Minimum allowed frequency of oscillation for the Gendy1
oscillator, so gives the largest period the duration is allowed
to take on.


@section{argument}
 maxfreq

Maximum allowed frequency of oscillation for the Gendy1
oscillator, so gives the smallest period the duration is allowed
to take on.


@section{argument}
 ampscale

Normally 0.0 to 1.0, multiplier for the distribution's delta
value for amplitude. An ampscale of 1.0 allows the full range
of  -1 to 1 for a change of amplitude.


@section{argument}
 durscale

Normally 0.0 to 1.0, multiplier for the distribution's delta
value for duration. An ampscale of 1.0 allows the full range of
-1 to 1 for a change of duration.


@section{argument}
 initCPs

Initialise the number of control points in the memory.
Xenakis specifies 12. There would be this number of control
points per cycle of the oscillator, though the oscillator's
period will constantly change due to the duration distribution.


@section{argument}
 knum

Current number of utilised control points, allows modulation.


@section{argument}
 a

Parameter for Lehmer random number generator perturbed by
Xenakis as in


@racketblock[
((old*a)+c)%1.0
::

]
@section{argument}
 c

Parameter for Lehmer random number generator perturbed by
Xenakis.


@section{argument}
 mul
Output will be multiplied by this value.

@section{argument}
 add
This value will be added to the output.

@section{discussion}
 
All parameters can be modulated at control rate except for 
@racketblock[initCPs:: which is used only at initialisation.


]
@section{Examples}
 
@section{warning}
 
if you have lots of CPs and you have fast frequencies, the CPU cost goes up a lot because a new CP move happens every sample!
::


@racketblock[
//LOUD! defaults like a rougher Gendy1
{Pan2.ar(Gendy2.ar)}.play

//advantages of messing with the random number generation- causes periodicities
{Pan2.ar(Gendy2.ar(a:MouseX.kr(0.0,1.0),c:MouseY.kr(0.0,1.0)))}.play

(
{Pan2.ar(
Normalizer.ar(
RLPF.ar(
RLPF.ar(Gendy2.ar(a:SinOsc.kr(0.4,0,0.05,0.05),c:SinOsc.kr(0.3,0,0.1,0.5)),
MouseX.kr(10,10000,'exponential'),0.05),
MouseY.kr(10,10000,'exponential'),0.05)
,0.9)
,Lag.kr(LFNoise0.kr(1),0.5))}.play
)



{Pan2.ar(Gendy2.ar(3,5,1.0,1.0,50,1000,MouseX.kr(0.05,1),MouseY.kr(0.05,1),15, 0.05,0.51,mul:0.5))}.play


//play me
{Pan2.ar(RLPF.ar(Gendy2.ar(1,3,minfreq:20,maxfreq:MouseX.kr(100,1000),durscale:0.0,initCPs:4),500,0.3, 0.2),0.0)}.play


//1 CP = random noise effect
{Pan2.ar(Gendy2.ar(initCPs:1))}.play

//2 CPs = suddenly an oscillator (though a fast modulating one here)
{Pan2.ar(Gendy2.ar(initCPs:2))}.play


//used as an LFO
(
{Pan2.ar(SinOsc.ar(Gendy2.kr(2,1,SinOsc.kr(0.1,0,0.49,0.51),SinOsc.kr(0.13,0,0.49,0.51),
3.4,3.5, SinOsc.kr(0.17,0,0.49,0.51), SinOsc.kr(0.19,0,0.49,0.51),10,10,mul:50, add:350), 0, 0.3), 0.0)}.play
)

//very angry wasp
{Pan2.ar(Gendy2.ar(0, 0, SinOsc.kr(0.1, 0, 0.1, 0.9),1.0, 50,1000, 1,0.005, 12, 12, 0.2,0.2,0.2), 0.0)}.play


//modulate distributions
//change of pitch as distributions change the duration structure and spectrum
{Pan2.ar(Gendy2.ar(MouseX.kr(0,7),MouseY.kr(0,7),mul:0.2), 0.0)}.play


//modulate num of CPs
{Pan2.ar(Gendy2.ar(knum:MouseX.kr(1,13),mul:0.2), 0.0)}.play


(//Gendy1 into Gendy2...with cartoon side effects
{Pan2.ar(Gendy2.ar(maxfreq:Gendy1.kr(5,4,0.3, 0.7, 0.1, MouseY.kr(0.1,10),
    1.0, 1.0, 5,5, 500, 600), knum:MouseX.kr(1,13),mul:0.2), 0.0)}.play
)

//use SINUS to track any oscillator and take CP positions from it, use adparam and ddparam as the inputs to sample
{Pan2.ar(Gendy2.ar(6,6,LFPulse.kr(100, 0, 0.4, 1.0), SinOsc.kr(30, 0, 0.5),mul:0.2), 0.0)}.play


(//try out near the corners especially
{Pan2.ar(Gendy2.ar(6,6,LFPulse.kr(MouseX.kr(0,200), 0, 0.4, 1.0),
    SinOsc.kr(MouseY.kr(0,200), 0, 0.5),mul:0.2), 0.0)}.play
)

//texture- the howling wind?
(
{
    Mix.fill(10,{
    var freq;

    freq= rrand(130,160.3);
    Pan2.ar(SinOsc.ar(Gendy2.ar(6.rand,6.rand,SinOsc.kr(0.1,0,0.49,0.51),SinOsc.kr(0.13,0,0.49,0.51),
        freq ,freq, SinOsc.kr(0.17,0,0.49,0.51), SinOsc.kr(0.19,0,0.49,0.51),
        12, 12, 0.4.rand, 0.4.rand, 200, 400), 0, 0.1), 1.0.rand2)
    });
}.play
)

//CAREFUL! mouse to far right causes explosion of sound
(
{Pan2.ar(
CombN.ar(
Resonz.ar(
Gendy2.ar(2,3,minfreq:1, maxfreq:MouseX.kr(10,700), initCPs:100),
MouseY.kr(50,1000), 0.1)
,0.1,0.1,5, 0.16
)
, 0.0)}.play
)

//storm
(
{
    var n;
    n=15;

    0.5*Mix.fill(n,{
    var freq, numcps;

    freq= rrand(130,160.3);
    numcps= rrand(2,20);
    Pan2.ar(Gendy2.ar(6.rand,6.rand,10.0.rand,10.0.rand,freq,freq*exprand(1.0,2.0),
        10.0.rand, 10.0.rand, numcps, SinOsc.kr(exprand(0.02,0.2), 0, numcps/2, numcps/2),
        10.0.rand, 10.0.rand, 0.5/(n.sqrt)), 1.0.rand2)
    });
}.play
)

//another traffic moment
(
{
    var n;
    n=10;

    Resonz.ar(
    Mix.fill(n,{
    var freq, numcps;

    freq= rrand(50,560.3);
    numcps= rrand(2,20);
    Pan2.ar(Gendy2.ar(6.rand,6.rand,1.0.rand,1.0.rand,freq ,freq,
        1.0.rand, 1.0.rand, numcps, SinOsc.kr(exprand(0.02,0.2), 0,
        numcps/2, numcps/2), 0.5/(n.sqrt)), 1.0.rand2)
    })
    ,MouseX.kr(100,2000), MouseY.kr(0.01,1.0), 0.3)
    ;
    }.play
)
::

]