feat: add initial implementation of squidgeTemplate plugin with basic gain parameter

Makefile

@@ -3,7 +3,7 @@
 # ------------------------------ #
 
 # Define your plugins here as space-separated names
-PLUGINS = SquidgeDistortion
+PLUGINS = SquidgeDistortion SquidgeFilter
 
 # --------------------------------------------------------------
 

core/Filter.cpp

@@ -1,71 +1,129 @@
 #include "Filter.hpp"
 #include <cmath>
 
-Filter::Filter(float initCutOff, float initSampleRate)
+#ifndef M_PI
-    : cutOff_(initCutOff), feedback_(0.0f), resonance_(0.1f), a1_(0.0f),
+#define M_PI 3.14159265358979323846
-      a2_(0.0f), a3_(0.0f), g_(0.0f), k_(2.0f), sampleRate_(initSampleRate),
+#endif
-      s1L_(0.0f), s2L_(0.0f), s1R_(0.0f), s2R_(0.0f), outZL_(0.0f),
-      outZR_(0.0f) {
-  recompute();
-};
 
-void Filter::process(const float *in, float *out, uint32_t frames) {
+Filter::Filter(float initCutOff, float initQ, float initSampleRate)
-  filter(in, out, frames, &s1L_, &s2L_, &outZL_);
+    : modulation_(0.0f), cutOff_(initCutOff), q_(initQ),
-};
+      sampleRate_(initSampleRate), type_(kLowPass), g_(0.0f), lpL_(0.0f),
-void Filter::processStereo(const float *inLeft, const float *inRight,
+      bpL_(0.0f), lpR_(0.0f), bpR_(0.0f) {
-                           float *outLeft, float *outRight, uint32_t frames) {
+  updateCoeffs();
-  filter(inLeft, outLeft, frames, &s1L_, &s2L_, &outZL_);
+}
-  filter(inRight, outRight, frames, &s1R_, &s2R_, &outZR_);
-};
 
-void Filter::filter(const float *in, float *out, uint32_t frames, float *s1,
+Filter::FilterType Filter::getType() const { return type_; }
-                    float *s2, float *outZ) {
+
-  for (uint32_t i = 0; i < frames; ++i) {
+float Filter::clampFreq(float freq) {
-    float x = in[i] + (feedback_ * (*outZ));
+  return std::fmin(std::fmax(freq, kFilterMin), kFilterMax);
-    float v3 = x - *s2;
+}
-    if (resonance_ > 0.995f && std::fabs(v3) < 1.0e-9f) {
+
-      v3 = 1.0e-6f;
+void Filter::updateCoeffs() {
-    }
+  float totalFreq = clampFreq(cutOff_ + modulation_);
-    float v1 = (a1_ * (*s1)) + (a2_ * v3);
+
-    float v2 = (*s2) + (a2_ * (*s1)) + (a3_ * v3);
+  float f = totalFreq / std::fmax(sampleRate_, 1.0f);
-    *s1 = (2.0f * v1) - *s1;
+
-    *s2 = (2.0f * v2) - *s2;
+  if (f > kMaxNormalizedFrequency)
-    out[i] = v2;
+    f = kMaxNormalizedFrequency;
-    *outZ = v2;
+  if (f < 0.0001f)
+    f = 0.0001f;
+
+  g_ = 2.0f * std::sin(M_PI * f);
+}
+
+float Filter::processFrame(float input, float &lp, float &bp) const {
+  float hp = input - (bp / q_) - lp;
+
+  bp = bp + g_ * hp;
+  lp = lp + g_ * bp;
+
+  switch (type_) {
+  case kHighPass:
+    return hp;
+  case kBandPass:
+    return bp;
+  case kNotch:
+    return input - lp;
+  case kLowPass:
+  default:
+    return lp;
   }
 }
 
-void Filter::recompute() {
+void Filter::process(const float *in, float *out, uint32_t frames,
-  float sr = std::fmax(sampleRate_, 1.0f);
+                     const float *modulation) {
-  float fc = std::fmin(std::fmax(cutOff_, 1.0f), 0.45f * sr);
+  float lp = lpL_;
-  g_ = std::tan(static_cast<float>(M_PI) * (fc / sr));
+  float bp = bpL_;
-  k_ = 2.0f * (1.0f - std::fmin(std::fmax(resonance_, 0.0f), 1.0f));
 
-  float denom = 1.0f + (g_ * (g_ + k_));
+  for (uint32_t i = 0; i < frames; ++i) {
-  a1_ = 1.0f / denom;
+    if (modulation != nullptr) {
-  a2_ = g_ * a1_;
+      if (std::abs(modulation[i] - modulation_) > 0.001f) {
-  a3_ = g_ * a2_;
+        setModulation(modulation[i]);
-};
+      }
+    }
+    out[i] = processFrame(in[i], lp, bp);
+  }
 
-void Filter::setCutOff(float newCutOff) {
+  lpL_ = lp;
-  cutOff_ = newCutOff;
+  bpL_ = bp;
-  recompute();
 }
+
+void Filter::processStereo(const float *inL, const float *inR, float *outL,
+                           float *outR, uint32_t frames,
+                           const float *modulation) {
+  float lpL = lpL_, bpL = bpL_;
+  float lpR = lpR_, bpR = bpR_;
+
+  for (uint32_t i = 0; i < frames; ++i) {
+    if (modulation != nullptr) {
+      if (std::abs(modulation[i] - modulation_) > 0.001f) {
+        setModulation(modulation[i]);
+      }
+    }
+
+    float inValL = (inL != nullptr) ? inL[i] : 0.0f;
+    float inValR = (inR != nullptr) ? inR[i] : 0.0f;
+
+    outL[i] = processFrame(inValL, lpL, bpL);
+    outR[i] = processFrame(inValR, lpR, bpR);
+  }
+
+  lpL_ = lpL;
+  bpL_ = bpL;
+  lpR_ = lpR;
+  bpR_ = bpR;
+}
+
 float Filter::getCutOff() const { return cutOff_; }
 
-void Filter::setFeedback(float newFeedback) {
+void Filter::setCutOff(float freq) {
-  feedback_ = std::fmin(std::fmax(newFeedback, 0.0f), 0.95f);
+  cutOff_ = clampFreq(freq);
+  updateCoeffs();
 }
-float Filter::getFeedback() const { return feedback_; }
 
-void Filter::setResonance(float newResonance) {
+float Filter::getQ() const { return q_; }
-  resonance_ = std::fmin(std::fmax(newResonance, 0.0f), 1.0f);
-  recompute();
-}
-float Filter::getResonance() const { return resonance_; }
 
-void Filter::setSampleRate(float newSampleRate) {
+void Filter::setQ(float q) {
-  sampleRate_ = newSampleRate;
+  q_ = std::fmin(std::fmax(q, kQMin), kQMax);
-  recompute();
+  updateCoeffs();
 }
+
+void Filter::setType(FilterType type) { type_ = type; }
+
 float Filter::getSampleRate() const { return sampleRate_; }
+
+void Filter::setSampleRate(float sr) {
+  if (sr > 0.0f) {
+    sampleRate_ = sr;
+    updateCoeffs();
+  }
+}
+
+float Filter::getModulation() const { return modulation_; }
+
+void Filter::setModulation(float mod) {
+  if (std::abs(modulation_ - mod) > 0.0001f) {
+    modulation_ = mod;
+    updateCoeffs();
+  }
+}

core/Filter.hpp

@@ -1,45 +1,55 @@
 #ifndef FILTER_HPP_INCLUDED
 #define FILTER_HPP_INCLUDED
-#ifndef M_PI
+
-#define M_PI 3.14159265358979323846
-#endif
 #include <cstdint>
 
+constexpr float kMaxNormalizedFrequency = 0.16667f;
+constexpr float kFilterMin = 20.0f;
+constexpr float kFilterMax = 10000.0f;
+constexpr float kQMin = 0.1f;
+constexpr float kQMax = 20.0f;
+
 class Filter {
 public:
-  Filter(float initCutOff = 1.0f, float initSampleRate = 48000.0f);
+  Filter(float initCutOff = 1000.0f, float initQ = 0.707f,
-  void process(const float *in, float *out, uint32_t frames);
+         float initSampleRate = 48000.0f);
-  void processStereo(const float *inLeft, const float *inRight, float *outLeft,
-                     float *outRight, uint32_t frames);
 
-  void recompute();
+  enum FilterType { kLowPass, kHighPass, kBandPass, kNotch, kFilterTypeCount };
-  void setCutOff(float newCutOff);
+
+  void setCutOff(float freq);
   float getCutOff() const;
-  void setFeedback(float newFeedback);
+
-  float getFeedback() const;
+  void setQ(float q);
-  void setResonance(float newResonance);
+  float getQ() const;
-  float getResonance() const;
+  void setSampleRate(float sr);
-  void setSampleRate(float newSampleRate);
   float getSampleRate() const;
+  void setType(FilterType type);
+  FilterType getType() const;
+  void setModulation(float mod);
+  float getModulation() const;
+
+  void process(const float *in, float *out, uint32_t frames,
+               const float *modulation = nullptr);
+  void processStereo(const float *inL, const float *inR, float *outL,
+                     float *outR, uint32_t frames,
+                     const float *modulation = nullptr);
 
 private:
-  void filter(const float *in, float *out, uint32_t frames, float *s1,
+  void updateCoeffs();
-              float *s2, float *outZ);
+  float modulation_;
+
+  float clampFreq(float freq);
+  float processFrame(float input, float &lp, float &bp) const;
+
   float cutOff_;
-  float feedback_;
+  float q_;
-  float resonance_;
-  float a1_;
-  float a2_;
-  float a3_;
-  float g_;
-  float k_;
   float sampleRate_;
-  float s1L_;
+  FilterType type_;
-  float s2L_;
+
-  float s1R_;
+  float g_;
-  float s2R_;
+
-  float outZL_;
+  float lpL_, bpL_;
-  float outZR_;
+  float lpR_, bpR_;
 };
 
-#endif // FILTER_HPP_INCLUDED
+#endif

core/Oscillator.cpp

@@ -0,0 +1,54 @@
+#include "Oscillator.hpp"
+
+#include <cmath>
+
+Oscillator::Oscillator(float initFreq)
+    : freq_(initFreq), gain_(100.0f), waveShape_(kWaveShapeSine),
+      sampleRate_(48000.f), phase_(0.0f), inc_(0.0f)
+{
+  recalc_();
+};
+
+void Oscillator::process(float *out, uint32_t frames)
+{
+  for (uint32_t i = 0; i < frames; ++i)
+  {
+    switch (waveShape_)
+    {
+    default:
+    case kWaveShapeSine:
+      out[i] = std::sinf(phase_ * 2.0f * M_PI) * gain_;
+      break;
+    }
+    phase_ += inc_;
+    if (phase_ >= 1.0f)
+      phase_ -= 1.0f;
+  }
+}
+
+void Oscillator::reset() { phase_ = 0; }
+
+void Oscillator::recalc_() { inc_ = freq_ / sampleRate_; }
+
+void Oscillator::setFrequency(float newFreq)
+{
+  freq_ = std::fmax(newFreq, 0.0f);
+  recalc_();
+}
+float Oscillator::getFrequency() const { return freq_; };
+
+void Oscillator::setGain(float newGain)
+{
+  gain_ = newGain > 0 ? newGain : 1.0f;
+}
+float Oscillator::getGain() const { return gain_; };
+
+void Oscillator::setSampleRate(float newSampleRate)
+{
+  sampleRate_ = newSampleRate > 0 ? newSampleRate : 48000.0f;
+  recalc_();
+}
+float Oscillator::getSampleRate() const { return sampleRate_; }
+
+void Oscillator::setWaveShape(WaveShape shape) { waveShape_ = shape; }
+Oscillator::WaveShape Oscillator::getWaveShape() const { return waveShape_; }

core/Oscillator.hpp

@@ -0,0 +1,41 @@
+#ifndef OSCILLATOR_HPP_INCLUDED
+#define OSCILLATOR_HPP_INCLUDED
+
+#include <cstdint>
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+class Oscillator {
+  enum WaveShape { kWaveShapeSine, kWaveShapeTriangle, kWaveShapeSquare };
+
+public:
+  Oscillator(float initFreq);
+  void process(float *out, uint32_t frames);
+
+  void setFrequency(float newFreq);
+  float getFrequency() const;
+
+  void setGain(float newGain);
+  float getGain() const;
+
+  void setSampleRate(float newSampleRate);
+  float getSampleRate() const;
+
+  void setWaveShape(WaveShape shape);
+  WaveShape getWaveShape() const;
+
+  void reset();
+
+private:
+  float freq_;
+  float gain_;
+  WaveShape waveShape_;
+  float sampleRate_;
+  float phase_;
+  float inc_;
+  void recalc_();
+};
+
+#endif // OSCILLATOR_HPP_INCLUDED

plugins/SquidgeDistortion/DistrhoPluginInfo.h

@@ -9,7 +9,7 @@
 #define DISTRHO_PLUGIN_NUM_INPUTS 2
 #define DISTRHO_PLUGIN_NUM_OUTPUTS 2
 
-#define DISTRHO_PLUGIN_NUM_PARAMETERS 6
+#define DISTRHO_PLUGIN_NUM_PARAMETERS 5
 
 #define DISTRHO_PLUGIN_WANT_PROGRAMS 0
 #define DISTRHO_PLUGIN_WANT_STATE 0

plugins/SquidgeDistortion/Makefile

@@ -1,7 +1,7 @@
 #!/usr/bin/make -f
 NAME = SquidgeDistortion
 
-FILES_DSP = SquidgeDistortion.cpp ../../core/Gain.cpp ../../core/Clipper.cpp ../../core/Mixer.cpp ../../core/Filter.cpp
+FILES_DSP = SquidgeDistortion.cpp ../../core/Gain.cpp ../../core/Clipper.cpp ../../core/Mixer.cpp
 
 TARGETS = vst3 clap
 

plugins/SquidgeDistortion/SquidgeDistortion.cpp

@@ -5,7 +5,6 @@
 #include <cmath>
 
 #include "../../core/Clipper.hpp"
-#include "../../core/Filter.hpp"
 #include "../../core/Gain.hpp"
 #include "../../core/Mixer.hpp"
 
@@ -27,14 +26,11 @@ public:
   enum Parameters {
     kParamGain,
     kParamClipMode,
-    kParamFilter,
-    kParamFilterFeedback,
     kParamMixVolume,
-    kParamResonance,
     kParameterCount // must be last
   };
   SquidgeDistortion()
-      : Plugin(kParameterCount, 0, 0), gain_(2.0f), mixer_(1.0f), filter_(440) {
+      : Plugin(kParameterCount, 0, 0), gain_(2.0f), mixer_(1.0f) {
     mixer_.setInputGain(kChannelDry, 0.0f);
     mixer_.setInputGain(kChannelWet, 1.0f);
   }
@@ -75,22 +71,6 @@ protected:
       parameter.enumValues.values =
           const_cast<ParameterEnumerationValue *>(sClipModes);
       break;
-    case kParamFilter:
-      parameter.name = "Filter";
-      parameter.symbol = "filter";
-      parameter.ranges.min = 20.0f;
-      parameter.ranges.def = 1000.0f;
-      parameter.ranges.max = 10000.0f;
-      parameter.hints = kParameterIsAutomatable;
-      break;
-    case kParamFilterFeedback:
-      parameter.name = "Feedback";
-      parameter.symbol = "filterfeedback";
-      parameter.ranges.min = 0.0f;
-      parameter.ranges.def = 0.0f;
-      parameter.ranges.max = 0.95f;
-      parameter.hints = kParameterIsAutomatable;
-      break;
     case kParamMixVolume:
       parameter.name = "Dry/Wet";
       parameter.symbol = "drywetvolume";
@@ -99,14 +79,6 @@ protected:
       parameter.ranges.max = 1.0f;
       parameter.hints = kParameterIsAutomatable;
       break;
-    case kParamResonance:
-      parameter.name = "Resonance";
-      parameter.symbol = "resonance";
-      parameter.ranges.min = 0.0f;
-      parameter.ranges.def = 0.1f;
-      parameter.ranges.max = 1.0f;
-      parameter.hints = kParameterIsAutomatable;
-      break;
     }
   }
 
@@ -116,14 +88,8 @@ protected:
       return gain_.getGain();
     case kParamClipMode:
       return (float)clipper_.getMode();
-    case kParamFilter:
-      return (float)filter_.getCutOff();
-    case kParamFilterFeedback:
-      return (float)filter_.getFeedback();
     case kParamMixVolume:
       return mixer_.getInputGain(kChannelWet);
-    case kParamResonance:
-      return (float)filter_.getResonance();
     }
     return 0.0f;
   }
@@ -138,19 +104,10 @@ protected:
                         static_cast<float>(Clipper::kClipperModeCount - 1));
       clipper_.setMode(static_cast<Clipper::ClipperMode>(std::lround(value)));
       break;
-    case kParamFilter:
-      filter_.setCutOff(value);
-      break;
-    case kParamFilterFeedback:
-      filter_.setFeedback(value);
-      break;
     case kParamMixVolume:
       mixer_.setInputGain(kChannelWet, value);
       mixer_.setInputGain(kChannelDry, 1.0f - value);
       break;
-    case kParamResonance:
-      filter_.setResonance(value);
-      break;
     }
   }
 
@@ -166,24 +123,17 @@ protected:
                         buffers_.clippedR, frames);
     clipper_.processStereo(buffers_.clippedL, buffers_.clippedR,
                            buffers_.clippedL, buffers_.clippedR, frames);
-    filter_.processStereo(buffers_.clippedL, buffers_.clippedR, buffers_.lpL,
-                          buffers_.lpR, frames);
 
-    const float *inputsL[2] = {inputs[0], buffers_.lpL};
+    const float *inputsL[2] = {inputs[0], buffers_.clippedL};
-    const float *inputsR[2] = {inputs[1], buffers_.lpR};
+    const float *inputsR[2] = {inputs[1], buffers_.clippedR};
 
     mixer_.processStereo(inputsL, inputsR, outputs[0], outputs[1], frames);
   }
 
-  void sampleRateChanged(double newSr) override {
-    filter_.setSampleRate(static_cast<float>(newSr));
-  }
-
 private:
   Gain gain_;
   Clipper clipper_;
   Mixer<2> mixer_;
-  Filter filter_;
   AudioBuffers buffers_;
 
   DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(SquidgeDistortion);

plugins/SquidgeFilter/DistrhoPluginInfo.h

@@ -0,0 +1,28 @@
+#ifndef DISTRHO_PLUGIN_INFO_H_INCLUDED
+#define DISTRHO_PLUGIN_INFO_H_INCLUDED
+
+#define DISTRHO_PLUGIN_NAME "SquidgeFilter"
+#define DISTRHO_PLUGIN_AUTHOR "SquidgeSoft"
+#define DISTRHO_PLUGIN_URI "moe.liam.squidgesoft.SquidgeFilter"
+#define DISTRHO_PLUGIN_CATEGORY "fx"
+
+#define DISTRHO_PLUGIN_NUM_INPUTS 2
+#define DISTRHO_PLUGIN_NUM_OUTPUTS 2
+
+#define DISTRHO_PLUGIN_NUM_PARAMETERS 3
+
+#define DISTRHO_PLUGIN_WANT_TIMEPOS 1
+
+#define DISTRHO_PLUGIN_WANT_PROGRAMS 0
+#define DISTRHO_PLUGIN_WANT_STATE 0
+#define DISTRHO_PLUGIN_WANT_TIMEPOS 1
+
+#define DISTRHO_PLUGIN_HAS_UI 0
+#define DISTRHO_PLUGIN_IS_SYNTH 0
+
+#define DISTRHO_PLUGIN_PRIV_ID "moe.liam.squidgesoft.SquidgeFilter"
+#define DISTRHO_PLUGIN_BRAND "SquidgeSoft"
+
+#define DISTRHO_PLUGIN_CLAP_ID "moe.liam.squidgesoft.SquidgeFilter"
+
+#endif

plugins/SquidgeFilter/Makefile

@@ -0,0 +1,11 @@
+#!/usr/bin/make -f
+NAME = SquidgeFilter
+
+FILES_DSP = SquidgeFilter.cpp ../../core/Filter.cpp ../../core/Oscillator.cpp
+
+TARGETS = vst3 clap
+
+include ../../dpf/Makefile.plugins.mk
+
+all: $(TARGETS)
+

plugins/SquidgeFilter/SquidgeFilter.cpp

@@ -0,0 +1,198 @@
+#include "DistrhoDetails.hpp"
+#include "DistrhoPlugin.hpp"
+#include "DistrhoPluginInfo.h"
+
+#include "../../core/Filter.hpp"
+#include "../../core/Oscillator.hpp"
+
+START_NAMESPACE_DISTRHO
+
+const int BUFFER_SIZE = 16384;
+
+class SquidgeFilter : public Plugin {
+
+public:
+  enum Parameters {
+    kParamFreq,
+    kParamResonance,
+    kParamType,
+    kParamLFOSyncMode,
+    kParamLFOAmount,
+    kParameterCount // must be last
+  };
+
+  SquidgeFilter()
+      : Plugin(kParameterCount, 0, 0), filter_(440.0f, 2.0f, 48000.0f),
+        lfo_(20.0f), lfoSync_(0.0f) {
+    filter_.setType(Filter::kLowPass);
+  }
+
+protected:
+  const char *getLabel() const override { return "SquidgeFilter"; }
+  const char *getDescription() const override {
+    return "Simple State Variable Filter.";
+  }
+  const char *getMaker() const override { return "SquidgeSoft"; }
+  const char *getLicense() const override { return "GPL3"; }
+  uint32_t getVersion() const override { return d_version(0, 1, 0); }
+  int64_t getUniqueId() const override { return d_cconst('S', 'Q', 'F', 'T'); }
+
+  void initParameter(uint32_t index, Parameter &parameter) override {
+    switch (index) {
+    case kParamFreq:
+      parameter.name = "Frequency";
+      parameter.symbol = "frequency";
+      parameter.ranges.min = 20.0f;
+      parameter.ranges.def = 440.0f;
+      parameter.ranges.max = 10000.0f;
+      parameter.hints = kParameterIsAutomatable | kParameterIsLogarithmic;
+      break;
+
+    case kParamResonance:
+      parameter.name = "Resonance";
+      parameter.symbol = "resonance";
+      parameter.ranges.min = 0.9f;
+      parameter.ranges.def = 2.0f;
+      parameter.ranges.max = 20.0f;
+      parameter.hints = kParameterIsAutomatable;
+      break;
+
+    case kParamType:
+      parameter.name = "Filter Type";
+      parameter.symbol = "type";
+      parameter.ranges.min = 0.0f;
+      parameter.ranges.def = 0.0f;
+      parameter.ranges.max = Filter::kFilterTypeCount - 1;
+      parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
+      parameter.enumValues.count = Filter::kFilterTypeCount;
+      parameter.enumValues.restrictedMode = true;
+
+      static const ParameterEnumerationValue sTypes[Filter::kFilterTypeCount] =
+          {{0.0f, "Low Pass"},
+           {1.0f, "High Pass"},
+           {2.0f, "Band Pass"},
+           {3.0f, "Notch"}};
+      parameter.enumValues.values =
+          const_cast<ParameterEnumerationValue *>(sTypes);
+      break;
+    case kParamLFOAmount:
+      parameter.name = "LFO Amount";
+      parameter.symbol = "lfoamount";
+      parameter.ranges.min = 0.0f;
+      parameter.ranges.def = 0.0f;
+      parameter.ranges.max = 1000.0f;
+
+      parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
+      break;
+    case kParamLFOSyncMode:
+      parameter.name = "LFO Sync";
+      parameter.symbol = "lfosync";
+      parameter.ranges.min = 0.0f;
+      parameter.ranges.def = 3.0f;
+      parameter.ranges.max = 6.0f;
+
+      parameter.hints = kParameterIsAutomatable | kParameterIsInteger;
+
+      static const ParameterEnumerationValue sModes[] = {
+          {0.0f, "1/1 Bar"}, {1.0f, "1/2 Bar"},  {2.0f, "1/4 Bar"},
+          {3.0f, "1/8 Bar"}, {4.0f, "1/16 Bar"}, {5.0f, "1/32 Bar"},
+          {6.0f, "1/64 Bar"}};
+
+      parameter.enumValues.count = 7;
+      parameter.enumValues.restrictedMode = true;
+      parameter.enumValues.values =
+          const_cast<ParameterEnumerationValue *>(sModes);
+      break;
+    }
+  }
+
+  float getParameterValue(uint32_t index) const override {
+    switch (index) {
+    case kParamFreq:
+      return filter_.getCutOff();
+    case kParamResonance:
+      return filter_.getQ();
+    case kParamType:
+      return static_cast<float>(filter_.getType());
+    case kParamLFOAmount:
+      return lfo_.getGain();
+      break;
+    case kParamLFOSyncMode:
+      return lfoSync_;
+    };
+    return 0.0f;
+  }
+
+  void setParameterValue(uint32_t index, float value) override {
+    switch (index) {
+    case kParamFreq:
+      filter_.setCutOff(value);
+      break;
+    case kParamResonance:
+      filter_.setQ(value);
+      break;
+    case kParamLFOAmount:
+      lfo_.setGain(value);
+      break;
+    case kParamLFOSyncMode:
+      lfoSync_ = value;
+      break;
+    case kParamType:
+      int typeIdx = static_cast<int>(std::fmin(std::fmax(value, 0.0f), 3.0f));
+      filter_.setType(static_cast<Filter::FilterType>(typeIdx));
+      break;
+    }
+  }
+
+  void run(const float **inputs, float **outputs, uint32_t frames) override {
+
+    const TimePosition &timePos = getTimePosition();
+
+    float targetFreq = 4.0f;
+
+    if (timePos.bbt.valid && timePos.playing &&
+        timePos.bbt.beatsPerMinute > 0.0) {
+      float bpb = static_cast<float>(timePos.bbt.beatsPerBar);
+      float bpm = static_cast<float>(timePos.bbt.beatsPerMinute);
+      float bar = static_cast<float>(timePos.bbt.bar);
+
+      if (bar != currentBar_) {
+        lfo_.reset();
+        currentBar_ = bar;
+      }
+
+      float baseFreq = (bpm / 60.0f) / bpb;
+
+      static const float multipliers[] = {1.0f,  2.0f,  4.0f, 8.0f,
+                                          16.0f, 32.0f, 64.0f};
+
+      targetFreq = baseFreq * multipliers[static_cast<int>(lfoSync_)];
+    } else {
+      targetFreq = 1.0f;
+    }
+
+    lfo_.setFrequency(targetFreq);
+    lfo_.process(lfoBuffer_, frames);
+
+    filter_.processStereo(inputs[0], inputs[1], outputs[0], outputs[1], frames,
+                          lfoBuffer_);
+  }
+
+  void sampleRateChanged(double newSr) override {
+    filter_.setSampleRate(static_cast<float>(newSr));
+    lfo_.setSampleRate(newSr);
+  }
+
+private:
+  Filter filter_;
+  Oscillator lfo_;
+  float lfoSync_;
+  uint32_t currentBar_ = 0;
+  float lfoBuffer_[BUFFER_SIZE];
+
+  DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(SquidgeFilter);
+};
+
+Plugin *createPlugin() { return new SquidgeFilter(); }
+
+END_NAMESPACE_DISTRHO

plugins/SquidgeTemplate/DistrhoPluginInfo.h

@@ -0,0 +1,26 @@
+#ifndef DISTRHO_PLUGIN_INFO_H_INCLUDED
+#define DISTRHO_PLUGIN_INFO_H_INCLUDED
+
+#define DISTRHO_PLUGIN_NAME "SquidgeTemplate"
+#define DISTRHO_PLUGIN_AUTHOR "SquidgeSoft"
+#define DISTRHO_PLUGIN_URI "moe.liam.squidgesoft.SquidgeTemplate"
+#define DISTRHO_PLUGIN_CATEGORY "fx"
+
+#define DISTRHO_PLUGIN_NUM_INPUTS 2
+#define DISTRHO_PLUGIN_NUM_OUTPUTS 2
+
+#define DISTRHO_PLUGIN_NUM_PARAMETERS 1
+
+#define DISTRHO_PLUGIN_WANT_TIMEPOS 0
+
+#define DISTRHO_PLUGIN_WANT_PROGRAMS 0
+#define DISTRHO_PLUGIN_WANT_STATE 0
+#define DISTRHO_PLUGIN_HAS_UI 0
+#define DISTRHO_PLUGIN_IS_SYNTH 0
+
+#define DISTRHO_PLUGIN_PRIV_ID "moe.liam.squidgesoft.SquidgeTemplate"
+#define DISTRHO_PLUGIN_BRAND "SquidgeSoft"
+
+#define DISTRHO_PLUGIN_CLAP_ID "moe.liam.squidgesoft.SquidgeTemplate"
+
+#endif

plugins/SquidgeTemplate/Makefile

@@ -0,0 +1,10 @@
+#!/usr/bin/make -f
+NAME = squidgeTemplate
+
+FILES_DSP = squidgeTemplate.cpp ../../core/Gain.cpp
+
+TARGETS = vst3 clap
+
+include ../../dpf/Makefile.plugins.mk
+
+all: $(TARGETS)

plugins/SquidgeTemplate/SquidgeTemplate.cpp

@@ -0,0 +1,79 @@
+#include "DistrhoDetails.hpp"
+#include "DistrhoPlugin.hpp"
+#include "DistrhoPluginInfo.h"
+
+#include "../../core/Gain.hpp"
+
+START_NAMESPACE_DISTRHO
+
+class squidgeTemplate : public Plugin
+{
+public:
+    enum Parameters
+    {
+        kParamGain,
+        kParameterCount
+    };
+
+    squidgeTemplate()
+        : Plugin(kParameterCount, 0, 0), gain_(1.0f)
+    {
+    }
+
+protected:
+    const char *getLabel() const override { return "squidgeTemplate"; }
+    const char *getDescription() const override { return "Generic squidge plugin template."; }
+    const char *getMaker() const override { return "SquidgeSoft"; }
+    const char *getLicense() const override { return "GPL3"; }
+    uint32_t getVersion() const override { return d_version(0, 1, 0); }
+    int64_t getUniqueId() const override { return d_cconst('S', 'Q', 'T', 'P'); }
+
+    void initParameter(uint32_t index, Parameter &parameter) override
+    {
+        switch (index)
+        {
+        case kParamGain:
+            parameter.name = "Gain";
+            parameter.symbol = "gain";
+            parameter.ranges.min = 0.0f;
+            parameter.ranges.def = 1.0f;
+            parameter.ranges.max = 2.0f;
+            parameter.hints = kParameterIsAutomatable;
+            break;
+        }
+    }
+
+    float getParameterValue(uint32_t index) const override
+    {
+        if (index == kParamGain)
+            return gain_.getGain();
+        return 0.0f;
+    }
+
+    void setParameterValue(uint32_t index, float value) override
+    {
+        if (index == kParamGain)
+            gain_.setGain(value);
+    }
+
+    void run(const float **inputs, float **outputs, uint32_t frames) override
+    {
+        gain_.processStereo(inputs[0], inputs[1], outputs[0], outputs[1], frames);
+    }
+
+    void sampleRateChanged(double /*newSr*/) override
+    {
+    }
+
+private:
+    Gain gain_;
+
+    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(squidgeTemplate)
+};
+
+Plugin *createPlugin()
+{
+    return new squidgeTemplate();
+}
+
+END_NAMESPACE_DISTRHO