81 lines
2.3 KiB
C++
81 lines
2.3 KiB
C++
#pragma once
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#include <JuceHeader.h>
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enum class BlepWave : int { Sine = 0, Saw, Square, Triangle };
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class BlepOsc
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{
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public:
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void prepare (double sampleRate) { sr = sampleRate; resetPhase(); }
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void setWave (BlepWave w) { wave = w; }
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void setFrequency (float f) { freq = juce::jmax (0.0f, f); inc = freq / (float) sr; }
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void resetPhase (float p = 0.0f) { phase = juce::jlimit (0.0f, 1.0f, p); }
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inline float process()
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{
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// phase in [0..1)
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float out = 0.0f;
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float t = phase;
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phase += inc;
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if (phase >= 1.0f) phase -= 1.0f;
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switch (wave)
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{
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case BlepWave::Sine: out = std::sin (2.0f * juce::MathConstants<float>::pi * t); break;
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case BlepWave::Saw:
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{
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// naive saw in [-1..1]
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float s = 2.0f * t - 1.0f;
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// apply BLEP at the discontinuity crossing t=0
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s -= polyBlep (t, inc);
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out = s;
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} break;
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case BlepWave::Square:
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{
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float s = (t < 0.5f ? 1.0f : -1.0f);
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// rising edge at 0.0, falling at 0.5
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s += polyBlep (t, inc) - polyBlep (std::fmod (t + 0.5f, 1.0f), inc);
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out = s;
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} break;
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case BlepWave::Triangle:
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{
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// integrate the BLEP square for band-limited tri
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float sq = (t < 0.5f ? 1.0f : -1.0f);
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sq += polyBlep (t, inc) - polyBlep (std::fmod (t + 0.5f, 1.0f), inc);
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// leaky integrator to keep DC under control
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z1 = z1 + (sq - z1) * inc;
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out = 2.0f * z1; // scale
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} break;
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}
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return out;
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}
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private:
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// PolyBLEP as in Valimäki/Huovilainen
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static inline float polyBlep (float t, float dt)
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{
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// t in [0..1)
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if (t < dt)
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{
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t /= dt;
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return t + t - t * t - 1.0f;
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}
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else if (t > 1.0f - dt)
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{
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t = (t - 1.0f) / dt;
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return t * t + t + t + 1.0f;
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}
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return 0.0f;
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}
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double sr = 44100.0;
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float freq = 440.0f, inc = 440.0f / 44100.0f;
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float phase = 0.0f;
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float z1 = 0.0f;
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BlepWave wave = BlepWave::Sine;
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};
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