InstaGrain/Source/GrainVoice.cpp

#include "GrainVoice.h"

GrainVoice::GrainVoice() {}

void GrainVoice::prepare (double sampleRate)
{
    currentSampleRate = sampleRate;
    cloud.prepare (sampleRate);
    adsr.setSampleRate (sampleRate);
}

void GrainVoice::noteOn (int midiNote, float velocity)
{
    currentNote = midiNote;
    velocityGain = velocity;
    voiceActive = true;

    // Pitch offset relative to sample's root note
    cloud.midiPitchOffset = (float) (midiNote - rootNote.load());

    // Update ADSR
    adsrParams.attack  = attackTime.load();
    adsrParams.decay   = decayTime.load();
    adsrParams.sustain = sustainLevel.load();
    adsrParams.release = releaseTime.load();
    adsr.setParameters (adsrParams);
    adsr.noteOn();

    cloud.reset();
}

void GrainVoice::noteOff()
{
    adsr.noteOff();
}

void GrainVoice::forceStop()
{
    adsr.reset();
    voiceActive = false;
    currentNote = -1;
    cloud.reset();
}

void GrainVoice::processBlock (juce::AudioBuffer<float>& output, int numSamples,
                                const juce::AudioBuffer<float>& sourceBuffer)
{
    if (! voiceActive) return;

    // Render cloud into temp buffer
    juce::AudioBuffer<float> voiceBuffer (output.getNumChannels(), numSamples);
    voiceBuffer.clear();

    cloud.processBlock (voiceBuffer, numSamples, sourceBuffer);

    // Compute ADSR envelope once per sample (not per channel!)
    std::vector<float> envBuffer ((size_t) numSamples);
    for (int i = 0; i < numSamples; ++i)
        envBuffer[(size_t) i] = adsr.getNextSample() * velocityGain;

    // Apply envelope and mix into output
    for (int ch = 0; ch < output.getNumChannels(); ++ch)
    {
        const float* voiceData = voiceBuffer.getReadPointer (ch);
        float* outData = output.getWritePointer (ch);

        for (int i = 0; i < numSamples; ++i)
            outData[i] += voiceData[i] * envBuffer[(size_t) i];
    }

    // Check if ADSR has finished
    if (! adsr.isActive())
    {
        voiceActive = false;
        currentNote = -1;
        cloud.reset();
    }
}