From 2ea0409fe7a9d2ded38dda6ae8a5f58b9dd78452 Mon Sep 17 00:00:00 2001
From: Gordon JC Pearce <gordonjcp@gmail.com>
Date: Tue, 19 Aug 2025 23:33:47 +0100
Subject: [PATCH] stereo chorus

---
 plugin/chorus.cpp      | 40 +++++++++++++++++-----------------------
 plugin/chorus.hpp      |  8 ++++----
 plugin/generator.cpp   |  2 --
 plugin/sonnenlicht.cpp |  6 +++---
 4 files changed, 24 insertions(+), 32 deletions(-)

diff --git a/plugin/chorus.cpp b/plugin/chorus.cpp
index 79685ca..a07edef 100644
--- a/plugin/chorus.cpp
+++ b/plugin/chorus.cpp
@@ -23,12 +23,11 @@
 
 #include <cstdio>
 
-Chorus::Chorus(uint32_t xbufferSize, double xsampleRate) {  // no parameters, programs, or states
+extern double sampleRate;
+extern uint32_t bufferSize;
 
-    bufferSize = xbufferSize;
-    sampleRate = xsampleRate;
+Chorus::Chorus() {  // no parameters, programs, or states
 
-    lpfIn = new float[bufferSize];
     lpfOut1 = new float[bufferSize];
     lpfOut2 = new float[bufferSize];
     ram = new float[DELAYSIZE];  // probably needs to be calculated based on sample rate
@@ -36,8 +35,10 @@ Chorus::Chorus(uint32_t xbufferSize, double xsampleRate) {  // no parameters, pr
     fastPhase = 0;
     slowPhase = 0;
 
-    postFilter1 = new SVF(8000, 1.3);
-    postFilter2 = new SVF(8000, 0.54);
+    postFilter1l = new SVF(POSTCUTOFF, .546);
+    postFilter2l = new SVF(POSTCUTOFF, 1.324);
+    postFilter1r = new SVF(POSTCUTOFF, .546);
+    postFilter2r = new SVF(POSTCUTOFF, 1.324);
 
     // lfo values taken from a rough simulation
     fastOmega = 6.283 * 5.7 / sampleRate;  // approximate, can be adjusted
@@ -45,18 +46,18 @@ Chorus::Chorus(uint32_t xbufferSize, double xsampleRate) {  // no parameters, pr
 
     // zero out the delay buffer
     memset(ram, 0, sizeof(float) * DELAYSIZE);
-    memset(lpfIn, 0, sizeof(float) * bufferSize);
     memset(lpfOut1, 0, sizeof(float) * bufferSize);
     memset(lpfOut2, 0, sizeof(float) * bufferSize);
 }
 
 Chorus::~Chorus() {
-    delete lpfIn;
     delete lpfOut1;
     delete lpfOut2;
     delete ram;
-    delete postFilter1;
-    delete postFilter2;
+    delete postFilter1l;
+    delete postFilter2l;
+    delete postFilter1r;
+    delete postFilter2r;
 }
 
 void Chorus::run(const float *input, float **outputs, uint32_t frames) {
@@ -76,15 +77,6 @@ void Chorus::run(const float *input, float **outputs, uint32_t frames) {
 
         ram[delayptr] = input[i];
 
-        // lowpass filter
-
-        // now we need to calculate the delay
-        // I don't know how long the Solina's delay lines are so I'm guessing 2-4ms for now
-        // normalised mod depths, from a quick simulation of the LFO block:
-        //   0deg 0.203 slow 0.635 fast
-        // 120deg 0.248 slow 0.745 fast
-        // 240deg 0.252 slow 0.609 fast
-
 #define BASE 0.05
 #define AMT 0.00175
 
@@ -121,13 +113,15 @@ void Chorus::run(const float *input, float **outputs, uint32_t frames) {
         s0 = ram[tap & 0x3ff];
         out240 = ((s1 - s0) * frac) + s0;
 
-        lpfOut1[i] = (out0 + out120 + out240) / 3;
+        lpfOut1[i] = (out0 + (out120 * 0.66) + (out240 * 0.33));
+        lpfOut2[i] = (out0 + (out120 * 0.33) + (out240 * 0.66));
 
         delayptr++;
         delayptr &= 0x3ff;
     }
 
-    postFilter1->runSVF(lpfOut1, lpfOut2, frames);
-    postFilter2->runSVF(lpfOut2, outputs[0], frames);
-    memcpy (outputs[1], outputs[0], frames * sizeof(float)); // only mono output for now
+    postFilter1l->runSVF(lpfOut1, lpfOut1, frames);
+    postFilter2l->runSVF(lpfOut1, outputs[0], frames);
+    postFilter1r->runSVF(lpfOut2, lpfOut2, frames);
+    postFilter2r->runSVF(lpfOut2, outputs[1], frames);
 }
diff --git a/plugin/chorus.hpp b/plugin/chorus.hpp
index ecb7b31..657de58 100644
--- a/plugin/chorus.hpp
+++ b/plugin/chorus.hpp
@@ -24,15 +24,15 @@
 // total size of delay line buffer
 #define DELAYSIZE 1028
 
+#define POSTCUTOFF 10000
+
 class Chorus {
    public:
-    Chorus(uint32_t xbufferSize, double xsampleRate);
+    Chorus();
     ~Chorus();
     void run(const float *input, float **outputs, uint32_t frames);
-    double sampleRate;
     
    private:
-    uint32_t bufferSize;
     double fastPhase, fastOmega;
     double slowPhase, slowOmega;
     double fastLfo, slowLfo;
@@ -43,6 +43,6 @@ class Chorus {
     float *lpfIn;
     float *lpfOut1, *lpfOut2;
 
-    SVF *preFilter, *postFilter1, *postFilter2;
+    SVF *postFilter1l, *postFilter2l, *postFilter1r, *postFilter2r;
 };
 #endif
diff --git a/plugin/generator.cpp b/plugin/generator.cpp
index 5924b8d..03f206f 100644
--- a/plugin/generator.cpp
+++ b/plugin/generator.cpp
@@ -31,9 +31,7 @@ extern uint32_t bufferSize;
 // unit-local global
 static float envTc[2];
 
-// Generator::Generator(uint32_t bufferSize, double xSampleRate) {
 Generator::Generator() {
-    // sampleRate = xSampleRate;
     output = new float[bufferSize];
     // create the phase increments for each semitone
     for (uint8_t i = 0; i < 12; i++) {
diff --git a/plugin/sonnenlicht.cpp b/plugin/sonnenlicht.cpp
index 483f881..3cabb5e 100644
--- a/plugin/sonnenlicht.cpp
+++ b/plugin/sonnenlicht.cpp
@@ -20,6 +20,7 @@
 
 double sampleRate;
 uint32_t bufferSize;
+
 START_NAMESPACE_DISTRHO
 
 Sonnenlicht::Sonnenlicht() : Plugin(kParameterCount, 0, 0) {
@@ -27,11 +28,10 @@ Sonnenlicht::Sonnenlicht() : Plugin(kParameterCount, 0, 0) {
 
     sampleRate = getSampleRate();
     bufferSize = getBufferSize();
+
     genny = new Generator();
-
     assigner = new Assigner(genny->voices);
-
-    chorus = new Chorus(getBufferSize(), sampleRate);
+    chorus = new Chorus();
 }
 
 Sonnenlicht::~Sonnenlicht() {