Harmonic Shepard tone, y axis controls pitch.

lib/scale/scale.h

@@ -2,6 +2,28 @@
 #define YAW_SCALE_INCLUDED
 
 #include <vector>
+#include <string>
+
+struct Note
+{
+    std::string name;
+    double hz;
+    unsigned int number;
+};
+
+static std::vector<std::string> defaultNoteNames = {
+    "A",
+    "A#",
+    "B",
+    "C",
+    "C#",
+    "D",
+    "D#",
+    "E",
+    "F",
+    "F#",
+    "G",
+    "G#"};
 
 class Scale
 {
@@ -10,6 +32,7 @@ class Scale
     // freqs in hz, periods in samples
     std::vector<double> frequencies;
     std::vector<double> periods;
+    std::vector<std::string> names;
 
 public:
     void newSampleRate(double rate)
@@ -23,16 +46,18 @@ public:
     // Default ctor: 12TET @ 48kHz
     Scale(double hz = 440.0)
     {
-        hz /= 32.0;
+        hz /= 64.0;
 
         for (int i = 0; i < 12 * 8; ++i)
         {
             frequencies.push_back(hz);
             periods.push_back(sampleRate / hz);
+            names.push_back(defaultNoteNames[i % 12]);
             hz *= exp2(1.0 / 12.0);
         }
     }
 
+
     double getNearestPeriod(double period)
     {
         for (auto note : periods)
@@ -45,6 +70,26 @@ public:
         return 0;
     }
 
+    unsigned int getNearestNoteNumber(double hz)
+    {
+        for ( unsigned int i = 0; i < frequencies.size(); ++i )
+        {
+            if (hz < frequencies[i]) return i;
+        }
+
+        return 0;
+    }
+
+    double getNearestFrequency(double hz)
+    {
+        for (auto note : frequencies)
+        {
+            if (hz < note) return note;
+        }
+
+        return 0;
+    }
+
     // TODO: parse scala files. new ctor that parses arbitrary scales
 };
 

src/yaw-shepard/CMakeLists.txt

@@ -10,6 +10,7 @@ dpf_add_plugin(yaw-tab-shepard
 
 target_include_directories(yaw-tab-shepard PUBLIC
     "."
-    "../../lib/wintab")
+    "../../lib/wintab"
+    "../../lib/scale")
 
 target_compile_definitions(yaw-tab-shepard PUBLIC YAW_USE_WINTAB)

src/yaw-shepard/DistrhoPluginInfo.h

@@ -19,7 +19,8 @@ enum Parameters {
     kParameterButtonA,
     kParameterButtonB,
     kParameterTime,
-    kParameterCount
+    kFundamentalFrequency,
+    kParameterCount,
 };
 
 #endif // DISTRHO_PLUGIN_INFO_H_INCLUDED

src/yaw-shepard/dsp.cpp

@@ -18,7 +18,7 @@ protected:
 	const char* getLabel() const override { return "yaw-shepard"; }
 	const char* getDescription() const override { return "Generalized Shepard tone, tablet UI"; }
 	const char* getMaker() const override { return "yaw-audio"; }
-	const char* getHomePage() const override { return "https://yaw.man/plugins/yaw-tab"; }
+	const char* getHomePage() const override { return "https://yaw.man/plugins/yaw-shepard"; }
 	const char* getLicense() const override { return "Fuck You Pay Me"; }
 	uint32_t    getVersion() const override { return d_version(1, 0, 0); }
 	int64_t     getUniqueId() const override { return d_cconst('y', 's', 'p', 'd'); }
@@ -33,6 +33,13 @@ protected:
 
 		switch (index)
 		{
+		case kFundamentalFrequency:
+			parameter.name = "hz";
+			parameter.symbol = "hz";
+			parameter.hints = kParameterIsOutput;
+			parameter.ranges.def = 55.0f;
+			parameter.ranges.min = 55.0f;
+			parameter.ranges.max = 880.0f;
 		case ktpax:
 			parameter.name = "x";
 			parameter.symbol = "x";
@@ -105,6 +112,7 @@ protected:
 		synth.process(*outputs, frames);
 		parity = !parity;
 		fParameters[kParameterTime] += parity ? 1 : -1;
+		fParameters[kFundamentalFrequency] = synth.hzFund;
 	}
 
 private:

src/yaw-shepard/synth.cpp

@@ -57,7 +57,7 @@ void Synth::process(float* output, const uint32_t frames)
     for(uint32_t i = 0; i < frames; i++){
 
         //Set pitch.
-        hz = hzFund = spectrumPhase * fMin + fMin;
+        hz = hzFund = exp2(spectrumPhase) * fMin;
 
         bool isOddHarmonic = true;
         
@@ -80,7 +80,7 @@ void Synth::process(float* output, const uint32_t frames)
             isOddHarmonic = !isOddHarmonic;
         }
 
-        output[i] *= volume / static_cast<double>(NUM_VOICES);
+        output[i] *= 32 * volume / static_cast<double>(NUM_VOICES);
 
         //Wrapping.
         spectrumPhase += spectrumPhaseVelocity * sampleInterval;
@@ -102,8 +102,10 @@ void Synth::setPhaseVelocity(double in){
     spectrumPhaseVelocity = 2.0 * (in - 0.5);
 }
 
+//Vary pitch of fundamental in a non-wrapping kinda way.
+//Current range is six octaves, current bottom is 110.0 Hz (A3)
 void Synth::setTimbre(double in){
-    
+    fMin = exp2(in * 2.0) * 110.0;
 }
 
 void Synth::setVolume(double in){

src/yaw-shepard/synth.h

@@ -7,7 +7,7 @@ struct Voice
     double phase;
 };
 
-constexpr unsigned int NUM_VOICES = 256;
+constexpr unsigned int NUM_VOICES = 512;
 constexpr unsigned int VOICE_MASK = NUM_VOICES - 1;
 
 class Synth
@@ -22,6 +22,9 @@ public:
     void shiftUp();
     void shiftDown();
 
+    //Current fundamental frequency of blit.
+    double hzFund = fMin;
+
 private:
     //Phase must persist between run invocation.
     //Phase of each voice, considered a function on the unit circle.
@@ -32,9 +35,8 @@ private:
     //Revolutions per second of spectrum phase.
     double spectrumPhaseVelocity = 0.0;
     //Lowest fundamental frequency of blit.
-    static inline constexpr double fMin = 55.0;
-    //Current fundamental frequency of blit.
-    double hzFund = fMin;
+    double fMin = 55.0;
+
     double hzNyq = 24000.0;
     double sampleInterval = 1.0 / 48000.0;
 };

src/yaw-shepard/ui.cpp

@@ -1,6 +1,6 @@
 #include "ui.h"
-#ifdef DEBUG
 #include <format>
+#ifdef DEBUG
 #include <optional>
 #endif
 
@@ -113,6 +113,8 @@ void TabUI::parameterChanged(uint32_t index, float value)
 	{
 		switch (index)
 		{
+		case (kFundamentalFrequency):
+			hz = value;
 		case (ktpax):
 			pkt.x = value;
 		case (ktpay):
@@ -125,8 +127,6 @@ void TabUI::parameterChanged(uint32_t index, float value)
 		return;
 	}
 
-	getTabletData();
-	repaint();
 }
 
 void TabUI::uiIdle()
@@ -173,6 +173,16 @@ void TabUI::onNanoDisplay()
 	fontSize(15.0f);
 	textLineHeight(1.f);
 
+	// Numerical feedback.
+	beginPath();
+	fillColor(200, 200, 200);
+	textBox(0.f, 15.f, 250.f,
+			std::format("Frequency: {:.3f}\nNearest: {}\n",
+						hz, scale.getNearestNoteNumber(hz))
+				.c_str(),
+			nullptr);
+	closePath();
+
 // Report tablet errors.
 #ifdef DEBUG
 	if (!tab.initialized)

src/yaw-shepard/ui.h

@@ -1,5 +1,6 @@
 #include "DistrhoUI.hpp"
 #include "tablet.h"
+#include "scale.h"
 #ifdef DEBUG
 #include <format>
 #include <optional>
@@ -63,6 +64,10 @@ private:
     ButtonMappingWidget AButtonWidget;
     ButtonMappingWidget BButtonWidget;
 
+    // For displaying frequency.
+    float hz = 55.f;
+    Scale scale{440.0};
+
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(TabUI)
 };