132 lines
2.3 KiB
Text
132 lines
2.3 KiB
Text
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#lang scribble/manual
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@(require (for-label racket))
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@title{Rotate2}
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Rotate a sound field.@section{related}
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Classes/BiPanB2, Classes/DecodeB2, Classes/PanB, Classes/PanB2
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@section{categories}
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UGens>Multichannel>Ambisonics, UGens>Multichannel>Panners
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@section{description}
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Rotate2 can be used for rotating an ambisonic B-format sound field around
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an axis. Rotate2 does an equal power rotation so it also works well on
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stereo sounds. It takes two audio inputs (x, y) and an angle control
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(pos). It outputs two channels (x, y). It computes this:
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@racketblock[
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xout = cos(angle) * xin + sin(angle) * yin;
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::
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]
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@racketblock[
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yout = cos(angle) * yin - sin(angle) * xin;
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::
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where angle = pos * pi, so that -1 becomes -pi and +1 becomes +pi. This
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allows you to use an LFSaw to do continuous rotation around a circle.
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]
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@section{classmethods}
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@section{method}
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ar, kr
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@section{argument}
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x
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Input signal X.
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@section{argument}
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y
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Input signal Y.
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@section{argument}
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pos
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angle to rotate around the circle from -1 to +1. -1 is 180
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degrees, -0.5 is left, 0 is forward, +0.5 is right, +1 is behind.
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@section{Examples}
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@racketblock[
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(
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{
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var w, x, y, p, q, a, b, c, d;
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p = WhiteNoise.ar(0.05); // source
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q = LFSaw.ar(200,0,0.03)+LFSaw.ar(200.37,0,0.03)+LFSaw.ar(201,0,0.03);
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// B-format encode 2 signals at opposite sides of the circle
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#w, x, y = PanB2.ar(p, -0.5) + PanB2.ar(q, 0.5);
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#x, y = Rotate2.ar(x, y, MouseX.kr(-1,1));
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// B-format decode to quad
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#a, b, c, d = DecodeB2.ar(4, w, x, y);
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[a, b, d, c] // reorder to my speaker arrangement: Lf Rf Lr Rr
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}.play;
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)
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// Rotation of stereo sound:
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(
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{
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// rotation via lfo
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var x, y;
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x = PinkNoise.ar(0.4);
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y = LFTri.ar(800) * LFPulse.kr(3,0,0.3,0.2);
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#x, y = Rotate2.ar(x, y, LFSaw.kr(0.1));
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[x,y]
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}.play;
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)
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{
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// rotation via mouse
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var x, y;
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x = Mix.fill(4, { LFSaw.ar(200 + 2.0.rand2, 0, 0.1) });
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y = SinOsc.ar(900) * LFPulse.kr(3,0,0.3,0.2);
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#x, y = Rotate2.ar(x, y, MouseX.kr(0,2));
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[x,y]
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}.play;
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// Rotate B-format about Z axis:
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wout = win;
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zout = zin;
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#xout, yout = Rotate2.ar(xin, yin, pos);
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// Rotate B-format about Y axis:
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wout = win;
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yout = yin;
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#xout, zout = Rotate2.ar(xin, zin, pos);
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// Rotate B-format about X axis:
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wout = win;
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xout = xin;
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#yout, zout = Rotate2.ar(yin, zin, pos);
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::
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]
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