Prototype

Source/dsp/StepSequencer.h

@@ -17,6 +17,7 @@ struct Step
     int  semitone = 0;    // -12 .. +12
     float cents  = 0.0f;  // -50 .. +50
     bool slide   = false;
+    bool accent  = false;
 };
 
 class StepSequencer
@@ -31,6 +32,20 @@ public:
             s = Step{};
     }
 
+    void shift (int dir)
+    {
+        if (dir == 0)
+            return;
+
+        std::array<Step, numSteps> rotated = steps;
+
+        for (int i = 0; i < numSteps; ++i)
+        {
+            const int from = (i - dir + numSteps) % numSteps;
+            steps[i] = rotated[from];
+        }
+    }
+
     int stepsPerBeatFromRate (int rateIndex) const
     {
         // 0: 1/4, 1: 1/8, 2: 1/8T, 3: 1/16, 4: 1/32

Source/dsp/SynthVoice.h

@@ -13,8 +13,12 @@ public:
     {
         Waveform waveA = Waveform::saw;
         Waveform waveB = Waveform::square;
-        float detuneRatio = 1.0f;
-        float mix = 0.5f;
+        float osc1Coarse = 0.0f;
+        float osc2Coarse = 0.0f;
+        float osc1Fine = 0.0f;
+        float osc2Fine = 0.0f;
+        float osc1Phase = 0.0f;
+        float osc2Phase = 0.0f;
         float cutoff = 7000.0f;
         float resonance = 0.15f;
         float attack = 0.005f;
@@ -23,11 +27,22 @@ public:
         float release = 0.4f;
         float glide = 0.12f;
         float master = 0.9f;
+        float drive = 0.0f;
+        float ringMod = 0.0f;
+        float detuneRatio = 1.0f;
+        float mix = 0.5f;
     };
 
+    void addPhase (float phaseOffset)
+    {
+        phaseA = frac (phaseA + phaseOffset);
+        phaseB = frac (phaseB + phaseOffset);
+    }
+
     void prepare (double sr)
     {
         sampleRate = (float) sr;
+        accentSmoothCoef = 1.0f - std::exp (-1.0f / (0.003f * sampleRate));
         reset();
     }
 
@@ -40,12 +55,16 @@ public:
         env = 0.0f;
         envStage = Stage::idle;
         gate = false;
+        accentLevel = 1.0f;
+        accentSmooth = 1.0f;
     }
 
     void setParams (const Params& p) { params = p; }
 
     bool isActive() const { return gate; }
 
+    void setAccentLevel (float level) { accentLevel = level; }
+
     void noteOn (float freqHz, bool legato)
     {
         targetFreq = freqHz;
@@ -153,6 +172,9 @@ private:
         updateEnvelope();
         updateGlide();
 
+        // Smooth the accent gain so it ramps in/out instead of clicking.
+        accentSmooth += (accentLevel - accentSmooth) * accentSmoothCoef;
+
         const float incA = currentFreq / sampleRate;
         const float incB = (currentFreq * params.detuneRatio) / sampleRate;
 
@@ -164,9 +186,24 @@ private:
 
         float out = (1.0f - params.mix) * a + params.mix * b;
 
+        if (params.ringMod > 0.0f)
+            out = (1.0f - params.ringMod) * out + params.ringMod * (a * b);
+
+        const float preFilter = out;
         out = processFilter (out);
 
-        return out * env * params.master;
+        // Accented steps also get a touch of the unfiltered signal so they cut
+        // through the mix (presence), not just a volume bump.
+        if (accentSmooth > 1.0f)
+            out += (accentSmooth - 1.0f) * 0.2f * preFilter;
+
+        if (params.drive > 0.0f)
+        {
+            const float wet = std::tanh (out * (1.0f + params.drive * 9.0f));
+            out = (1.0f - params.drive) * out + params.drive * wet;
+        }
+
+        return out * env * params.master * accentSmooth;
     }
 
     float sampleRate = 44100.0f;
@@ -184,6 +221,9 @@ private:
     float env = 0.0f;
     Stage envStage = Stage::idle;
     bool gate = false;
+    float accentLevel = 1.0f;
+    float accentSmooth = 1.0f;
+    float accentSmoothCoef = 0.01f;
 };
 
 } // namespace monostep

Source/dsp/WaveTables.h

@@ -2,6 +2,7 @@
 
 #include <cmath>
 #include <algorithm>
+#include <random>
 
 namespace monostep
 {
@@ -11,7 +12,11 @@ enum class Waveform : int
     sine = 0,
     triangle = 1,
     saw = 2,
-    square = 3
+    square = 3,
+    pulse = 4,
+    noise = 5,
+    sub = 6,
+    pluck = 7
 };
 
 inline float frac (float x)
@@ -63,6 +68,31 @@ inline float renderWave (Waveform w, float phase, float inc)
             v -= polyBlep (frac (f + 0.5f), inc);
             return v;
         }
+
+        case Waveform::pulse:
+        {
+            const float f = frac (phase);
+            return (f < 0.3f) ? 1.0f : -1.0f;
+        }
+
+        case Waveform::sub:
+        {
+            const float f = frac (phase * 0.25f);
+            return 4.0f * std::min (f, 1.0f - f) - 1.0f;
+        }
+
+        case Waveform::noise:
+        {
+            thread_local static std::mt19937 rng { std::random_device {}() };
+            thread_local static std::uniform_real_distribution<float> dist (-1.0f, 1.0f);
+            return dist (rng);
+        }
+
+        case Waveform::pluck:
+        {
+            const float f = frac (phase);
+            return 2.0f * std::sin (f * 6.283185307179586f * 2.0f) * std::exp (-10.0f * f);
+        }
     }
 
     return 0.0f;