Improve Hades distortion

gritwave · Feb 12, 2024 · a41f432 · a41f432
1 parent 0a365e6
commit a41f432
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Showing 3 changed files with 51 additions and 20 deletions.
diff --git a/lib/grit/eurorack/hades.cpp b/lib/grit/eurorack/hades.cpp
@@ -74,6 +74,27 @@ auto Hades::process(Buffer const& buffer, ControlInput const& inputs) -> Control
     };
 }
 
+auto Hades::Distortion::next() -> void
+{
+    _index = Index{int(_index) + 1};
+    if (_index == MaxIndex) {
+        _index = Index{0};
+    }
+}
+
+auto Hades::Distortion::operator()(float sample) -> float
+{
+    switch (_index) {
+        case TanhIndex: return _tanh(sample);
+        case HardIndex: return _hard(sample);
+        case FullWaveIndex: return _fullWave(sample);
+        case HalfWaveIndex: return _halfWave(sample);
+        case DiodeIndex: return _diode(sample);
+        default: break;
+    }
+    return sample;
+}
+
 auto Hades::Channel::setParameter(Parameter const& parameter) -> void
 {
     _parameter = parameter;
@@ -97,17 +118,7 @@ auto Hades::Channel::setParameter(Parameter const& parameter) -> void
     });
 }
 
-auto Hades::Channel::nextDistortionAlgorithm() -> void
-{
-    switch (_distortion.index()) {
-        case 0: _distortion = Distortion{HardClipperADAA1<float>{}}; break;
-        case 1: _distortion = Distortion{FullWaveRectifierADAA1<float>{}}; break;
-        case 2: _distortion = Distortion{HalfWaveRectifierADAA1<float>{}}; break;
-        case 3: _distortion = Distortion{DiodeRectifierADAA1<float>{}}; break;
-        case 4: _distortion = Distortion{TanhClipperADAA1<float>{}}; break;
-        default: break;
-    }
-}
+auto Hades::Channel::nextDistortionAlgorithm() -> void { _distortion.next(); }
 
 auto Hades::Channel::prepare(float sampleRate) -> void
 {
@@ -126,7 +137,7 @@ auto Hades::Channel::operator()(float sample) -> etl::pair<float, float>
     auto const mixed = (noise * mix) + (vinyl * (1.0F - mix));
 
     auto const drive   = remap(_parameter.amp, 1.0F, 4.0F);  // +12dB
-    auto const distOut = etl::visit([x = mixed * drive](auto& func) { return func(x); }, _distortion);
+    auto const distOut = _distortion(mixed * drive);
     return {_compressor(distOut, distOut), env};
 }
 

diff --git a/lib/grit/eurorack/hades.hpp b/lib/grit/eurorack/hades.hpp
@@ -62,6 +62,32 @@ struct Hades
     [[nodiscard]] auto process(Buffer const& buffer, ControlInput const& inputs) -> ControlOutput;
 
 private:
+    struct Distortion
+    {
+        Distortion() = default;
+
+        auto next() -> void;
+        [[nodiscard]] auto operator()(float sample) -> float;
+
+    private:
+        enum Index : int
+        {
+            TanhIndex = 0,
+            HardIndex,
+            FullWaveIndex,
+            HalfWaveIndex,
+            DiodeIndex,
+            MaxIndex,
+        };
+
+        Index _index{TanhIndex};
+        TanhClipperADAA1<float> _tanh{};
+        HardClipperADAA1<float> _hard{};
+        FullWaveRectifierADAA1<float> _fullWave{};
+        HalfWaveRectifierADAA1<float> _halfWave{};
+        DiodeRectifierADAA1<float> _diode{};
+    };
+
     struct Channel
     {
         struct Parameter
@@ -84,19 +110,12 @@ struct Hades
         [[nodiscard]] auto operator()(float sample) -> etl::pair<float, float>;
 
     private:
-        using Distortion = etl::variant<
-            TanhClipperADAA1<float>,
-            HardClipperADAA1<float>,
-            FullWaveRectifierADAA1<float>,
-            HalfWaveRectifierADAA1<float>,
-            DiodeRectifierADAA1<float>>;
-
         Parameter _parameter{};
 
         EnvelopeFollower<float> _envelope{};
         WhiteNoise<float> _whiteNoise{};
         AirWindowsVinylDither<float> _vinyl{};
-        Distortion _distortion{TanhClipperADAA1<float>{}};
+        Distortion _distortion{};
         Compressor<float> _compressor{};
     };
 

diff --git a/lib/grit/eurorack/hades_test.cpp b/lib/grit/eurorack/hades_test.cpp
@@ -56,6 +56,7 @@ TEST_CASE("grit/audio/eurorack: Hades")
             .gate2          = false,
         };
 
+        hades.nextDistortionAlgorithm();
         auto const cv = hades.process(buffer, controls);
         REQUIRE(cv.gate1 == true);
         REQUIRE(cv.gate2 == false);