From 5f3058f662b7222ea47a49ea2a450aa0491b5496 Mon Sep 17 00:00:00 2001
From: grm <grm@eyesin.space>
Date: Thu, 27 Nov 2025 18:33:13 +0200
Subject: feat: add global lfo index and viz for cutoff lfo

---
 src/synth_engine.h    |  4 +++-
 src/synth_engine_v2.c | 33 ++++++++++++++++++++++++++-------
 src/synth_gui.c       |  9 +++++++++
 3 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/src/synth_engine.h b/src/synth_engine.h
index a29c389..254bf21 100644
--- a/src/synth_engine.h
+++ b/src/synth_engine.h
@@ -110,6 +110,8 @@ typedef struct {
   adsr_t adsr;
   adsr_t f_adsr;
 
+  int lfo_on_cutoff;
+  float lfo_index;
   lfo_t lfo;
 
   int octave;
@@ -119,7 +121,7 @@ typedef struct {
   int deli;
   cc_t cc_del_time;
   cc_t cc_del_feedback;
-  unsigned long long counter;
+  unsigned long long delay_counter;
 
   int f_adsr_enabled;
   int filter;
diff --git a/src/synth_engine_v2.c b/src/synth_engine_v2.c
index e15df85..41cbcf4 100644
--- a/src/synth_engine_v2.c
+++ b/src/synth_engine_v2.c
@@ -147,9 +147,16 @@ do_fliter(synth_t *synth, float *sample, unsigned int sample_rate, int frame)
                             note->noteOffSample);
       if (adsr  < 0.1) adsr = 0.1;
       cutoff = cutoff * adsr;
+      reso = reso * adsr;
     }
   }
 
+  if (synth->lfo_on_cutoff) {
+    cutoff = cutoff + 22000 * CC_GET(lfo_amp) * osc_sin(synth->lfo_index);
+    if (cutoff <= 0) cutoff = 0.001;
+    synth->lfo_index = osc_sin_next(CC_GET(lfo_freq), synth->lfo_index);
+  }
+
   if (synth->filter) {
     if (cutoff == 0) cutoff = 0.001;
     lpf_update(reso, cutoff, sample_rate);
@@ -251,6 +258,10 @@ make_sample(synth_t * synth, unsigned int sample_rate, int frame)
   synth->adsr.d = CC_GET(adsr_d);
   synth->adsr.s = CC_GET(adsr_s);
   synth->adsr.r = CC_GET(adsr_r);
+
+  // global lfo
+  /* float glfo_value = osc_sin(synth->lfo_index); */
+  /* synth->lfo_index = osc_sin_next(CC_GET(lfo_freq), synth->lfo_index); */
   
   for (int i = 0; i < synth->midi_active_n; i++) {
     note = synth->midi_active[i];
@@ -261,7 +272,9 @@ make_sample(synth_t * synth, unsigned int sample_rate, int frame)
                           note->noteOffSample);
 
     float targ_freq = note->freq * CC_GET(pitch);
-    targ_freq = targ_freq + targ_freq * CC_GET(lfo_amp) * osc_sin(note->lfo_index);
+    float lfo_value = osc_sin(note->lfo_index);
+
+    targ_freq = targ_freq + targ_freq * CC_GET(lfo_amp) * lfo_value; //can switch to glfo
 
     note->lfo_index = osc_sin_next(CC_GET(lfo_freq), note->lfo_index);
 
@@ -346,17 +359,18 @@ get_frame(void *outputBuffer, synth_t *synth, int frame)
   if (!notes_active(synth)) {
     synth->f_adsr.elapsed = 0;
     synth->active = 0;
+    synth->lfo_index = 0.0f;
     // auto gain test
     //synth->cc_gain.target = 1;
   }
 
   if (!synth->delay) {
-    synth->counter = 0;
+    synth->delay_counter = 0;
   }
 
   sample = make_sample(synth, SAMPLE_RATE, frame);
-  synth->counter++;
-  if (synth->counter >= (unsigned long long)(synth->cc_del_time.target * SAMPLE_RATE)) {
+  synth->delay_counter++;
+  if (synth->delay_counter >= (unsigned long long)(synth->cc_del_time.target * SAMPLE_RATE)) {
     int idx = (synth->deli - (int)(synth->cc_del_time.target * SAMPLE_RATE)) % (SAMPLE_RATE * 10);
     float tmp;
     if (idx >= 0) {
@@ -545,6 +559,9 @@ init_synth(void)
   synth->f_adsr.r = 0.4;
   synth->f_adsr.elapsed = 0;
 
+  synth->lfo_on_cutoff = 0;
+  synth->lfo_index = 0.0f;
+
   synth->lfo.freq = 1.0f;
   synth->lfo.amp = 0.0f;
   synth->lfo.elapsed = 0;
@@ -569,11 +586,11 @@ init_synth(void)
   synth->delay = 0;
   synth->del = (float *) calloc(sizeof(float), SAMPLE_RATE * 30);
   synth->deli = 0;
-  synth->counter = 0;
+  synth->delay_counter = 0;
     
   synth->f_adsr_enabled = 0;
-  synth->filter = 1;
-  synth->biquad = 0;
+  synth->filter = 0;
+  synth->biquad = 1;
   synth->biquad_type = 'l';
   synth->clamp = 1;
 
@@ -654,6 +671,8 @@ free_synth(synth_t * synth)
 
   free(synth->del);
 
+  lpf_close();
+
   if (synth->patch_name) free(synth->patch_name);
   free(synth);
 }
diff --git a/src/synth_gui.c b/src/synth_gui.c
index db37bf7..4cdf37d 100644
--- a/src/synth_gui.c
+++ b/src/synth_gui.c
@@ -1234,6 +1234,15 @@ draw_main(synth_t *synth)
   draw_cc_circle(&synth->cc_f_adsr_r, 30 + (30 + foffset) * fb++, 260, 30, 30);
 
   draw_cc_hbar(&synth->cc_cutoff, 30, 300, 256, 24);
+  synth->lfo_on_cutoff = GuiCheckBox((Rectangle){30 + 256 + 6, 300, 12, 24},
+                                     "lfo", synth->lfo_on_cutoff);
+  if (synth->lfo_on_cutoff) {
+    float cutoff = synth->cc_cutoff.target;
+    cutoff = cutoff + 22000 * synth->cc_lfo_amp.target * osc_sin(synth->lfo_index);
+    if (cutoff <= 0) cutoff = 0.001;
+
+    generic_hbar(cutoff, 50, synth->cc_cutoff.min, synth->cc_cutoff.max, 30, 300, 256, 24);
+  }
   draw_cc_vbar(&synth->cc_resonance, 330, 20, 24, 256);
   //draw_cc_vbar(&synth->cc_adsr_s, 30, 250, 30, 30);
 
-- 
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