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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2017 - ROLI Ltd.
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 5 End-User License
Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
27th April 2017).
End User License Agreement: www.juce.com/juce-5-licence
Privacy Policy: www.juce.com/juce-5-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
namespace dsp
{
//==============================================================================
/**
Utility class for logarithmically smoothed linear values.
Logarithmically smoothed values can be more relevant than linear ones for
specific cases such as algorithm change smoothing, using two of them in
opposite directions.
The gradient of the logarithmic/exponential slope can be configured by
calling LogRampedValue::setLogParameters.
@see SmoothedValue
@tags{DSP}
*/
template <typename FloatType>
class LogRampedValue : public SmoothedValueBase <LogRampedValue <FloatType>>
{
public:
//==============================================================================
/** Constructor. */
LogRampedValue() = default;
/** Constructor. */
LogRampedValue (FloatType initialValue) noexcept
{
// Visual Studio can't handle base class initialisation with CRTP
this->currentValue = initialValue;
this->target = initialValue;
}
//==============================================================================
/** Sets the behaviour of the log ramp.
@param midPointAmplitudedB Sets the amplitude of the mid point in
decibels, with the target value at 0 dB
and the initial value at -inf dB
@param rateOfChangeShouldIncrease If true then the ramp starts shallow
and gets progressively steeper, if false
then the ramp is initially steep and
flattens out as you approach the target
value
*/
void setLogParameters (FloatType midPointAmplitudedB, bool rateOfChangeShouldIncrease) noexcept
{
jassert (midPointAmplitudedB < (FloatType) 0.0);
B = Decibels::decibelsToGain (midPointAmplitudedB);
increasingRateOfChange = rateOfChangeShouldIncrease;
}
//==============================================================================
/** Reset to a new sample rate and ramp length.
@param sampleRate The sample rate
@param rampLengthInSeconds The duration of the ramp in seconds
*/
void reset (double sampleRate, double rampLengthInSeconds) noexcept
{
jassert (sampleRate > 0 && rampLengthInSeconds >= 0);
reset ((int) std::floor (rampLengthInSeconds * sampleRate));
}
/** Set a new ramp length directly in samples.
@param numSteps The number of samples over which the ramp should be active
*/
void reset (int numSteps) noexcept
{
stepsToTarget = numSteps;
this->setCurrentAndTargetValue (this->target);
updateRampParameters();
}
//==============================================================================
/** Set a new target value.
@param newValue The new target value
*/
void setTargetValue (FloatType newValue) noexcept
{
if (newValue == this->target)
return;
if (stepsToTarget <= 0)
{
this->setCurrentAndTargetValue (newValue);
return;
}
this->target = newValue;
this->countdown = stepsToTarget;
source = this->currentValue;
updateRampParameters();
}
//==============================================================================
/** Compute the next value.
@returns Smoothed value
*/
FloatType getNextValue() noexcept
{
if (! this->isSmoothing())
return this->target;
--(this->countdown);
temp *= r; temp += d;
this->currentValue = jmap (temp, source, this->target);
return this->currentValue;
}
//==============================================================================
/** Skip the next numSamples samples.
This is identical to calling getNextValue numSamples times.
@see getNextValue
*/
FloatType skip (int numSamples) noexcept
{
if (numSamples >= this->countdown)
{
this->setCurrentAndTargetValue (this->target);
return this->target;
}
this->countdown -= numSamples;
auto rN = (FloatType) std::pow (r, numSamples);
temp *= rN;
temp += d * (rN - (FloatType) 1) / (r - (FloatType) 1);
this->currentValue = jmap (temp, source, this->target);
return this->currentValue;
}
private:
//==============================================================================
void updateRampParameters()
{
auto D = increasingRateOfChange ? B : (FloatType) 1 - B;
auto base = ((FloatType) 1 / D) - (FloatType) 1;
r = std::pow (base, (FloatType) 2 / (FloatType) stepsToTarget);
auto rN = std::pow (r, (FloatType) stepsToTarget);
d = (r - (FloatType) 1) / (rN - (FloatType) 1);
temp = 0;
}
//==============================================================================
bool increasingRateOfChange = true;
FloatType B = Decibels::decibelsToGain ((FloatType) -40);
int stepsToTarget = 0;
FloatType temp = 0, source = 0, r = 0, d = 1;
};
} // namespace dsp
} // namespace juce
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