Fix regression for monowave (#249)

* Fix regression for monowave

Conditionally drag the start position together with the loop window
Preserves old behavior for single cycle stuff
Regression caused pitch drift and microtonality
Add qualifier info in tips_and_tricks

Author: djdiskmachine

CHANGELOG

@@ -20,6 +20,8 @@ Various additions
     Fix audio dying on multithreaded systems (#236)
         * MIDI queue protected by mutex lock on X64
         * Fixes "audio suddenly dies" error
+    Fix regression caused in https://github.com/djdiskmachine/LittleGPTracker/pull/245
+        Fix introduced microtonality for single cycle osc, thank you @INFU-AV <3
 
 1.6.0-bacon11
     Slices decoupled from loop mode

docs/wiki/tips_and_tricks.md

@@ -128,11 +128,14 @@ loops — just chop anything away!
 You can use `LPOF` in a looping table to scroll a short loop window through a sample independently of playback pitch — a form of granular timestretching. Set a short loop on the instrument, then add a table that advances the loop position every tick:
 
 ```
-00 LPOF xxxx ---- ----
-01 HOP  0000 ---- ----
+00 LPOF xyzq 
+01 HOP  0000  
 ```
 
-Each tick, the loop window shifts forward by `xxxx` samples. The note's pitch is still determined by the loop length and oscillator tuning; the *content* of the loop changes as it travels through the sample. This lets you play a sample at a different speed than its pitch — stretching or compressing its duration without affecting the note you hear.
+Each tick, the loop window shifts forward by `xyzq` samples. The note's pitch is still determined by the loop length and note tuning tuning; the *content* of the loop changes as it travels through the sample. This lets you play a sample at a different speed than its pitch — stretching or compressing its duration without affecting the note you hear.
+This technique works in `LOOP`, `LOOP_PINGPONG`, `LOOPSYNC` and`ONESHOT` modes.
+In `OSCILLATOR` mode (wavetable) — `LPOF` only shifts the waveform
+window without advancing playback, preserving pitch stability for timbre scanning using monowave or single-cycle waveforms.
 
 **Sync to BPM (V_sync)**
 

sources/Application/Instruments/SampleInstrument.cpp

@@ -1087,31 +1087,63 @@ void SampleInstrument::ProcessCommand(int channel,FourCC cc,ushort value) {
 	if (!source_) return ;
 
 	switch(cc) {
-    case I_CMD_LPOF:
+    case I_CMD_LPOF: {
+        // LPOF (Loop Offset) shifts the loop window (rendLoopStart_,
+        // rendLoopEnd_) within the sample. Two coexisting use cases:
+        //
+        // 1) Wavetable / single-cycle synthesis (SILM_OSC):
+        //    The loop length defines the oscillator's pitch (freq * length /
+        //    driverRate). LPOF is used to scan across stored waveforms or
+        //    modulate timbre (e.g. PWM) WITHOUT changing pitch. We must NOT
+        //    move the playhead here — doing so makes pitch glide as the bounds
+        //    shift mid-cycle, producing unwanted microtonal artifacts.
+        //
+        // 2) Granular stretching (every other mode — loop, ping-pong, loopsync,
+        //    oneshot, sliced or not):
+        //    Advancing the playhead alongside the loop window drags playback
+        //    through the source faster than the note's natural rate, decoupling
+        //    stretch speed from pitch. With short loops + LPOF + HOP in a
+        //    table, this produces timestretch / breakbeat-style scrubbing.
+        //
+        //    In oneshot or slice modes the playhead may cross into territory
+        //    the user didn't anticipate (notes ending early, slices bleeding
+        //    into neighbors). That's intentional — these are useful artifacts,
+        //    not bugs.
+
+        SampleInstrumentLoopMode loopmode =
+            (SampleInstrumentLoopMode)loopMode_->GetInt();
+        bool dragPlayhead = (loopmode != SILM_OSC);
+
         if (value > 0x8000) {
+            // Backward shift (two's complement): 0xFFFF = -1, 0x8001 = -32767
             int shift = (int)(0x10000 - value);
-            if (shift >
-                rp->rendLoopStart_) { // Clamp so to not back out of sample
+            if (shift > rp->rendLoopStart_) { // Don't push start below sample 0
                 shift = rp->rendLoopStart_;
             }
             rp->rendLoopEnd_ -= shift;
             rp->rendLoopStart_ -= shift;
-            rp->position_ -= shift;
-        } else if (value > 0) { // LPOF 0000 is a no-op, this is not that
+            if (dragPlayhead) {
+                rp->position_ -= shift;
+            }
+        } else if (value > 0) { // LPOF 0000 is a no-op
             int sampleSize = source_->GetSize(rp->midiNote_);
             int shift = (int)value;
-            if (rp->rendLoopEnd_ + shift >=
-                sampleSize) { // Clamp so to not play outside sample
+            // Clamp so rendLoopEnd_ doesn't escape the sample. When the window
+            // hits the end, further forward LPOFs become no-ops — the loop is
+            // parked at the boundary until something resets it.
+            if (rp->rendLoopEnd_ + shift >= sampleSize) {
                 shift = sampleSize - rp->rendLoopEnd_;
             }
             if (shift > 0) {
                 rp->rendLoopEnd_ += shift;
                 rp->rendLoopStart_ += shift;
-                rp->position_ += shift;
+                if (dragPlayhead) {
+                    rp->position_ += shift;
+                }
             }
         }
         break;
-
+    }
     case I_CMD_PLOF: {
         if (!source_)
             return;

sources/Application/Model/Project.h

@@ -21,7 +21,7 @@
 
 #define PROJECT_NUMBER "1"
 #define PROJECT_RELEASE "6"
-#define BUILD_COUNT "0-bacon11"
+#define BUILD_COUNT "0-bacon12"
 
 #define MAX_TAP 3