tracktion_Envelope.cpp

Go to the documentation of this file.

 /*
    ,--.                     ,--.     ,--.  ,--.
  ,-'  '-.,--.--.,--,--.,---.|  |,-.,-'  '-.`--' ,---. ,--,--,      Copyright 2018
  '-.  .-'|  .--' ,-.  | .--'|     /'-.  .-',--.| .-. ||      \   Tracktion Software
    |  |  |  |  \ '-'  \ `--.|  \  \  |  |  |  |' '-' '|  ||  |       Corporation
    `---' `--'   `--`--'`---'`--'`--' `---' `--' `---' `--''--'    www.tracktion.com
*/
 
 
namespace tracktion { inline namespace engine
{
 
//==============================================================================
ExpEnvelope::ExpEnvelope()
{
    calculateAttackTime();
    calculateDecayTime();
    calculateReleaseTime();
}
 
void ExpEnvelope::calculateAttackTime()
{
    float samples = float (sampleRate * attackTime);
 
    attackCoeff = std::exp (-std::log ((1.0f + attackTCO) / attackTCO) / float (samples));
    attackOffset = (1.0f + attackTCO) * (1.0f - attackCoeff);
}
 
void ExpEnvelope::calculateDecayTime()
{
    float samples = float (sampleRate * decayTime);
 
    decayCoeff = std::exp (-std::log ((1.0f + decayTCO) / decayTCO) / samples);
    decayOffset = (sustainLevel - decayTCO) * (1.0f - decayCoeff);
}
 
void ExpEnvelope::calculateReleaseTime()
{
    float samples = float (sampleRate * releaseTime);
 
    releaseCoeff = std::exp (-std::log ((1.0f + releaseTCO) / releaseTCO) / samples);
    releaseOffset = -releaseTCO * (1.0f - releaseCoeff);
}
 
}} // namespace tracktion { inline namespace engine