74 lines
1.7 KiB
Text
74 lines
1.7 KiB
Text
class:: Pwalk
|
|
summary:: A one-dimensional random walk over a list of values that are embedded
|
|
related:: Classes/Pbrown
|
|
categories:: Streams-Patterns-Events>Patterns>List
|
|
|
|
ClassMethods::
|
|
|
|
method::new
|
|
|
|
argument::list
|
|
The items to be walked over.
|
|
|
|
argument::stepPattern
|
|
Returns integers that will be used to increment the index into list.
|
|
|
|
argument::directionPattern
|
|
Used to determine the behavior at boundaries. When the index crosses a boundary, the next direction is drawn from this stream: 1 means use stepPattern as is, -1 means go in the reverse direction. Common patterns:
|
|
definitionList::
|
|
## 1 || always wrap around to the other boundary.
|
|
## Pseq([1, -1], inf) || go forward first, then backward, then forward again.
|
|
::
|
|
|
|
argument::startPos
|
|
Where to start in the list.
|
|
|
|
Examples::
|
|
|
|
code::
|
|
(
|
|
a = Pwalk(
|
|
Array.series(20, 0, 1), // integers, 0-19
|
|
// steps up to 2 in either direction, weighted toward positive
|
|
Pwrand([-2, -1, 0, 1, 2], [0.05, 0.1, 0.15, 1, 0.1].normalizeSum, inf),
|
|
// reverse direction at boundaries
|
|
Pseq([1, -1], inf),
|
|
10); // start in the middle
|
|
x = a.asStream;
|
|
)
|
|
|
|
200.do({ x.next.post; ", ".post });
|
|
|
|
b = a.copy.directionPattern_(1); // this one will always wrap around
|
|
x = b.asStream;
|
|
|
|
200.do({ x.next.post; ", ".post });
|
|
|
|
|
|
|
|
// non-random walk: easy way to do up-and-down arpeggiation
|
|
s.boot;
|
|
(
|
|
a = Pwalk(
|
|
[60, 64, 67, 72, 76, 79, 84].midicps, // C major
|
|
Pseq([1], inf),
|
|
Pseq([1, -1], inf), // turn around at either end
|
|
0);
|
|
x = a.asStream;
|
|
|
|
SynthDef(\help_walk, { arg freq;
|
|
Out.ar(0, Saw.ar([freq, freq+1], 0.5) * EnvGen.kr(Env.perc(0.01, 0.1), doneAction: Done.freeSelf))
|
|
}).add;
|
|
)
|
|
|
|
(
|
|
r = Task({
|
|
{
|
|
Synth.new(\help_walk, [\freq, x.next]);
|
|
0.1.wait;
|
|
}.loop;
|
|
}).play(SystemClock);
|
|
)
|
|
|
|
r.stop;
|
|
::
|