juce_Panner.cpp

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   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 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-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::dsp
{
 
//==============================================================================
template <typename SampleType>
Panner<SampleType>::Panner()
{
    update();
    reset();
}
 
//==============================================================================
template <typename SampleType>
void Panner<SampleType>::setRule (Rule newRule)
{
    currentRule = newRule;
    update();
}
 
template <typename SampleType>
void Panner<SampleType>::setPan (SampleType newPan)
{
    jassert (newPan >= -1.0 && newPan <= 1.0);
 
    pan = jlimit (static_cast<SampleType> (-1.0), static_cast<SampleType> (1.0), newPan);
    update();
}
 
//==============================================================================
template <typename SampleType>
void Panner<SampleType>::prepare (const ProcessSpec& spec)
{
    jassert (spec.sampleRate > 0);
    jassert (spec.numChannels > 0);
 
    sampleRate = spec.sampleRate;
 
    reset();
}
 
template <typename SampleType>
void Panner<SampleType>::reset()
{
    leftVolume .reset (sampleRate, 0.05);
    rightVolume.reset (sampleRate, 0.05);
}
 
//==============================================================================
template <typename SampleType>
void Panner<SampleType>::update()
{
    SampleType leftValue, rightValue, boostValue;
 
    auto normalisedPan = static_cast<SampleType> (0.5) * (pan + static_cast<SampleType> (1.0));
 
    switch (currentRule)
    {
        case Rule::balanced:
            leftValue  = jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - normalisedPan);
            rightValue = jmin (static_cast<SampleType> (0.5), normalisedPan);
            boostValue = static_cast<SampleType> (2.0);
            break;
 
        case Rule::linear:
            leftValue  = static_cast<SampleType> (1.0) - normalisedPan;
            rightValue = normalisedPan;
            boostValue = static_cast<SampleType> (2.0);
            break;
 
        case Rule::sin3dB:
            leftValue  = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * (1.0 - normalisedPan)));
            rightValue = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * normalisedPan));
            boostValue = std::sqrt (static_cast<SampleType> (2.0));
            break;
 
        case Rule::sin4p5dB:
            leftValue  = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - normalisedPan)), 1.5));
            rightValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * normalisedPan), 1.5));
            boostValue = static_cast<SampleType> (std::pow (2.0, 3.0 / 4.0));
            break;
 
        case Rule::sin6dB:
            leftValue  = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - normalisedPan)), 2.0));
            rightValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * normalisedPan), 2.0));
            boostValue = static_cast<SampleType> (2.0);
            break;
 
        case Rule::squareRoot3dB:
            leftValue  = std::sqrt (static_cast<SampleType> (1.0) - normalisedPan);
            rightValue = std::sqrt (normalisedPan);
            boostValue = std::sqrt (static_cast<SampleType> (2.0));
            break;
 
        case Rule::squareRoot4p5dB:
            leftValue  = static_cast<SampleType> (std::pow (std::sqrt (1.0 - normalisedPan), 1.5));
            rightValue = static_cast<SampleType> (std::pow (std::sqrt (normalisedPan), 1.5));
            boostValue = static_cast<SampleType> (std::pow (2.0, 3.0 / 4.0));
            break;
 
        default:
            leftValue  = jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - normalisedPan);
            rightValue = jmin (static_cast<SampleType> (0.5), normalisedPan);
            boostValue = static_cast<SampleType> (2.0);
            break;
    }
 
    leftVolume .setTargetValue (leftValue  * boostValue);
    rightVolume.setTargetValue (rightValue * boostValue);
}
 
//==============================================================================
template class Panner<float>;
template class Panner<double>;
 
} // namespace juce::dsp