envelope.cpp

#include "envelope.h"

Envelope::Envelope(double attack, double decay, double sustain,
                   double release) {
  this->attack = attack;
  this->decay = decay;
  this->sustain = sustain;
  this->release = release;
}

double Envelope::adsFactor(int samplesElapsed) {
  if (samplesElapsed < (attack * SAMPLE_RATE))
    return ((double)samplesElapsed) / (attack * SAMPLE_RATE);
  if (samplesElapsed < ((decay + attack) * SAMPLE_RATE)) {
    return sustain +
           (1 - sustain) *
               (pow(1 - ((double)(samplesElapsed - (attack * SAMPLE_RATE)) /
                         (decay * SAMPLE_RATE)),
                    2));
  }
  return sustain;
}

double Envelope::getFactor(int samplesElapsed) {
  double factor;
  factor = adsFactor(samplesElapsed);
  return factor;
}

double Envelope::getFactor(int samplesElapsed, int releaseSample) {
  double factor, releaseLevel;
  if ((samplesElapsed - releaseSample) >= (release * SAMPLE_RATE))
    return 0;
  releaseLevel = adsFactor(samplesElapsed);
  factor = releaseLevel *
           (1 - (samplesElapsed - releaseSample) / (release * SAMPLE_RATE));
  if (factor < 0)
    factor = 0;
  if (factor > 1)
    factor = 1;
  return factor;
}

void Envelope::setAttack(double value) { attack = value; }

void Envelope::setDecay(double value) { decay = value; }

void Envelope::setSustain(double value) { sustain = value; }

void Envelope::setRelease(double value) { release = value; }

bool Envelope::isDead(int samplesElapsed, int releaseSample) {
  return ((samplesElapsed - releaseSample) > (release * SAMPLE_RATE));
}