fix(polysynth): change mapping of resonance into biquad

Author: SolarLiner

Cargo.lock

@@ -13,9 +13,11 @@ keywords.workspace = true
 crate-type = ["lib", "cdylib"]
 
 [dependencies]
-fastrand = { version = "2.1.1", default-features = false }
-fastrand-contrib = { version = "0.1.0", default-features = false }
-valib = { path = "../..", features = ["filters", "oversample", "oscillators", "voice", "voice-upsampled", "nih-plug"]}
 nih_plug = { workspace = true, features = ["standalone"] }
 nih_plug_vizia.workspace = true
-num-traits.workspace = true
+num-traits.workspace = true
+numeric_literals.workspace = true
+valib = { path = "../..", features = ["filters", "oversample", "oscillators", "voice", "voice-upsampled", "nih-plug"]}
+
+fastrand = { version = "2.1.1", default-features = false }
+fastrand-contrib = { version = "0.1.0", default-features = false }

examples/polysynth/Cargo.toml

@@ -5,6 +5,7 @@ use fastrand_contrib::RngExt;
 use nih_plug::nih_log;
 use nih_plug::util::{db_to_gain, db_to_gain_fast};
 use num_traits::{ConstOne, ConstZero};
+use numeric_literals::replace_float_literals;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Arc;
 use valib::dsp::{BlockAdapter, DSPMeta, DSPProcess, SampleAdapter};
@@ -431,15 +432,16 @@ impl<T: Scalar> FilterImpl<T> {
         }
     }
 
+    #[replace_float_literals(T::from_f64(literal))]
     fn set_params(&mut self, samplerate: T, cutoff: T, resonance: T) {
         match self {
             Self::Transistor(p) => {
                 p.set_cutoff(cutoff);
-                p.set_resonance(T::from_f64(4.) * resonance);
+                p.set_resonance(4. * resonance);
             }
             Self::Ota(p) => {
                 p.set_cutoff(cutoff);
-                p.set_resonance(T::from_f64(4.) * resonance);
+                p.set_resonance(4. * resonance);
             }
             Self::Svf(_, p) => {
                 p.set_cutoff(cutoff);
@@ -448,7 +450,7 @@ impl<T: Scalar> FilterImpl<T> {
             Self::Biquad(p) => {
                 p.update_coefficients(&Biquad::lowpass(
                     cutoff / samplerate,
-                    T::from_f64(4.7) * (T::from_f64(2.) * resonance - T::one()).simd_exp(),
+                    0.1 + 4.7 * (2. * resonance - 1.).simd_exp() * resonance,
                 ));
             }
         }
@@ -552,8 +554,8 @@ impl<T: Scalar> Filter<T> {
                 Svf::new(self.samplerate, cutoff, T::one() - resonance).with_saturator(Sinh),
             ),
             FilterType::Digital if !matches!(self.fimpl, FilterImpl::Biquad(..)) => {
-                let resonance =
-                    T::from_f64(4.7) * (T::from_f64(2.) * resonance - T::one()).simd_exp();
+                let resonance = T::from_f64(0.1)
+                    + T::from_f64(4.7) * (T::from_f64(2.) * resonance - T::one()).simd_exp();
                 FilterImpl::Biquad(
                     Biquad::lowpass(cutoff / self.samplerate, resonance)
                         .with_saturators(Default::default(), Default::default()),