47 lines
1.4 KiB
Text
47 lines
1.4 KiB
Text
// Phaser: six first-order allpass stages per side swept by a triangle LFO
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// on an exponential scale, feedback around the chain, the right side's
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// LFO a quarter cycle behind for width. Slow on pads is the 70s string
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// machine; fast with feedback is a swirl. `sync` > 0 locks the LFO to
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// that many beats.
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let N = 6
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let rate = param(0.25, 0.01, 8)
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let sync = param(0, 0, 16)
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let bpm = param(120, 20, 300)
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let depth = param(0.8, 0, 1)
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let center = param(900, 100, 4000)
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let feedback = param(0.5, 0, 0.95)
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let blend = param(0.5, 0, 1)
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var al = [Allpass1{}; N]
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var ar = [Allpass1{}; N]
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var lfo = 0.0
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var fbl = 0.0
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var fbr = 0.0
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fn coef(ph) {
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let tri = 2.0 * abs(2.0 * fract(ph) - 1.0) - 1.0
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let f = center * exp2(tri * depth * 2.0)
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let t = tan(PI * min(f, sample_rate * 0.45) / sample_rate)
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(t - 1.0) / (t + 1.0)
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}
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fn chain(a, x, c) {
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let y = x
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for i in 0..N {
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y = allpass1(a[i], y, c)
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}
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y
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}
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fn effect(l, r) {
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let hz = if sync > 0.0 { bpm / (60.0 * sync) } else { rate }
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lfo = advance(lfo, hz / sample_rate)
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let cl = coef(lfo)
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let cr = coef(lfo + 0.25)
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let yl = chain(al, l + fbl * feedback, cl)
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let yr = chain(ar, r + fbr * feedback, cr)
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fbl = yl
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fbr = yr
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// Equal parts dry and phased make the notches; `blend` fades them in.
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vec2(mix(l, (l + yl) * 0.5, blend * 2.0), mix(r, (r + yr) * 0.5, blend * 2.0))
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}
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