Source/WebCore/platform/audio/Cone.cpp

/*
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "Cone.h"
#include <wtf/MathExtras.h>

namespace WebCore {

ConeEffect::ConeEffect() = default;

double ConeEffect::gain(FloatPoint3D sourcePosition, FloatPoint3D sourceOrientation, FloatPoint3D listenerPosition) const
{
    if (sourceOrientation.isZero() || ((m_innerAngle == 360.0) && (m_outerAngle == 360.0)))
        return 1.0; // no cone specified - unity gain

    // Normalized source-listener vector
    FloatPoint3D sourceToListener = listenerPosition - sourcePosition;
    sourceToListener.normalize();

    sourceOrientation.normalize();

    // Due to precision issues, the dot product may be very slightly outside the range [-1.0, 1.0], which would
    // acos() to return NaN. For this reason, we have to make sure we clamp the dot product before calling acos().
    auto dotProduct = clampTo(sourceToListener.dot(sourceOrientation), -1.0, 1.0);

    // Angle between the source orientation vector and the source-listener vector
    double angle = rad2deg(acos(dotProduct));
    double absAngle = fabs(angle);

    // Divide by 2.0 here since API is entire angle (not half-angle)
    double absInnerAngle = fabs(m_innerAngle) / 2.0;
    double absOuterAngle = fabs(m_outerAngle) / 2.0;
    double gain = 1.0;

    if (absAngle <= absInnerAngle) {
        // No attenuation
        gain = 1.0;
    } else if (absAngle >= absOuterAngle) {
        // Max attenuation
        gain = m_outerGain;
    } else {
        // Between inner and outer cones
        // inner -> outer, x goes from 0 -> 1
        double x = (absAngle - absInnerAngle) / (absOuterAngle - absInnerAngle);
        gain = (1.0 - x) + m_outerGain * x;
    }

    return gain;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)