JUCE/modules/juce_dsp/processors/juce_Panner.cpp

/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   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
{

//==============================================================================
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 dsp
} // namespace juce