x3daudio.h

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    // A piecewise curve made up of linear segments used to
    // define DSP behaviour with respect to normalized distance.
    //
    // Note that curve point distances are normalized within [0.0f, 1.0f].
    // X3DAUDIO_EMITTER.CurveDistanceScaler must be used to scale the
    // normalized distances to user-defined world units.
    // For distances beyond CurveDistanceScaler * 1.0f,
    // pPoints[PointCount-1].DSPSetting is used as the DSP setting.
    //
    // All distance curve spans must be such that:
    //      pPoints[k-1].DSPSetting + ((pPoints[k].DSPSetting-pPoints[k-1].DSPSetting) / (pPoints[k].Distance-pPoints[k-1].Distance)) * (pPoints[k].Distance-pPoints[k-1].Distance) != NAN or infinite values
    // For all points in the distance curve where 1 <= k < PointCount.
    typedef struct X3DAUDIO_DISTANCE_CURVE
    {
        X3DAUDIO_DISTANCE_CURVE_POINT* pPoints;    // distance curve point array, must have at least PointCount elements with no duplicates and be sorted in ascending order with respect to Distance
        UINT32                         PointCount; // number of distance curve points, must be >= 2 as all distance curves must have at least two endpoints, defining DSP settings at 0.0f and 1.0f normalized distance
    } X3DAUDIO_DISTANCE_CURVE, *LPX3DAUDIO_DISTANCE_CURVE;
    static const X3DAUDIO_DISTANCE_CURVE_POINT X3DAudioDefault_LinearCurvePoints[2] = { 0.0f, 1.0f, 1.0f, 0.0f };
    static const X3DAUDIO_DISTANCE_CURVE       X3DAudioDefault_LinearCurve          = { (X3DAUDIO_DISTANCE_CURVE_POINT*)&X3DAudioDefault_LinearCurvePoints[0], 2 };

    // Cone:
    // Specifies directionality for a single-channel emitter by
    // scaling DSP behaviour with respect to the emitter's front orientation.
    // This is modeled using two sound cones: an inner cone and an outer cone.
    // On/within the inner cone, DSP settings are scaled by the inner values.
    // On/beyond the outer cone, DSP settings are scaled by the outer values.
    // If on both the cones, DSP settings are scaled by the inner values only.
    // Between the two cones, the scaler is linearly interpolated between the
    // inner and outer values.  Set both cone angles to 0 or X3DAUDIO_2PI for
    // omnidirectionality using only the outer or inner values respectively.
    typedef struct X3DAUDIO_CONE
    {
        FLOAT32 InnerAngle; // inner cone angle in radians, must be within [0.0f, X3DAUDIO_2PI]
        FLOAT32 OuterAngle; // outer cone angle in radians, must be within [InnerAngle, X3DAUDIO_2PI]

        FLOAT32 InnerVolume; // volume level scaler on/within inner cone, used only for matrix calculations, must be within [0.0f, 2.0f] when used
        FLOAT32 OuterVolume; // volume level scaler on/beyond outer cone, used only for matrix calculations, must be within [0.0f, 2.0f] when used
        FLOAT32 InnerLPF;    // LPF (both direct and reverb paths) coefficient scaler on/within inner cone, used only for LPF (both direct and reverb paths) calculations, must be within [0.0f, 1.0f] when used
        FLOAT32 OuterLPF;    // LPF (both direct and reverb paths) coefficient scaler on/beyond outer cone, used only for LPF (both direct and reverb paths) calculations, must be within [0.0f, 1.0f] when used
        FLOAT32 InnerReverb; // reverb send level scaler on/within inner cone, used only for reverb calculations, must be within [0.0f, 2.0f] when used
        FLOAT32 OuterReverb; // reverb send level scaler on/beyond outer cone, used only for reverb calculations, must be within [0.0f, 2.0f] when used
    } X3DAUDIO_CONE, *LPX3DAUDIO_CONE;
    static const X3DAUDIO_CONE X3DAudioDefault_DirectionalCone = { X3DAUDIO_PI/2, X3DAUDIO_PI, 1.0f, 0.708f, 1.0f, 0.75f, 0.708f, 1.0f };


    // Listener:
    // Defines a point of 3D audio reception.
    typedef struct X3DAUDIO_LISTENER
    {
        X3DAUDIO_VECTOR OrientFront; // orientation of front direction, used only for matrix and delay calculations, must be orthonormal with OrientTop when used
        X3DAUDIO_VECTOR OrientTop;   // orientation of top direction, used only for matrix and delay calculations, must be orthonormal with OrientFront when used

        X3DAUDIO_VECTOR Position; // position in user-defined world units, does not affect Velocity
        X3DAUDIO_VECTOR Velocity; // velocity vector in user-defined world units/second, used only for doppler calculations, does not affect Position
    } X3DAUDIO_LISTENER, *LPX3DAUDIO_LISTENER;

    // Emitter:
    // Defines a 3D audio source, divided into two classifications:
    //
    // Single-point -- For use with single-channel sounds.
    //                 Positioned at the emitter base, i.e. the channel radius
    //                 and azimuth are ignored if the number of channels == 1.
    //
    //                 May be omnidirectional or directional using a cone.
    //                 The cone originates from the emitter base position,
    //                 and is directed by the emitter's front orientation.
    //
    // Multi-point  -- For use with multi-channel sounds.
    //                 Each non-LFE channel is positioned using an
    //                 azimuth along the channel radius with respect to the
    //                 front orientation vector in the plane orthogonal to the
    //                 top orientation vector.  An azimuth of X3DAUDIO_2PI
    //                 specifies a channel is a LFE.  Such channels are
    //                 positioned at the emitter base and are calculated
    //                 with respect to pLFECurve only, never pVolumeCurve.
    //
    //                 Multi-point emitters are always omnidirectional,
    //                 i.e. the cone is ignored if the number of channels > 1.
    //
    // Note that many properties are shared among all channel points,
    // locking certain behaviour with respect to the emitter base position.
    // For example, doppler shift is always calculated with respect to the
    // emitter base position and so is constant for all its channel points.
    // Distance curve calculations are also with respect to the emitter base
    // position, with the curves being calculated independently of each other.
    // For instance, volume and LFE calculations do not affect one another.
    typedef struct X3DAUDIO_EMITTER
    {
        X3DAUDIO_CONE* pCone; // sound cone, used only with single-channel emitters for matrix, LPF (both direct and reverb paths), and reverb calculations, NULL specifies omnidirectionality
        X3DAUDIO_VECTOR OrientFront; // orientation of front direction, used only for emitter angle calculations or with multi-channel emitters for matrix calculations or single-channel emitters with cones for matrix, LPF (both direct and reverb paths), and reverb calculations, must be normalized when used
        X3DAUDIO_VECTOR OrientTop;   // orientation of top direction, used only with multi-channel emitters for matrix calculations, must be orthonormal with OrientFront when used

        X3DAUDIO_VECTOR Position; // position in user-defined world units, does not affect Velocity
        X3DAUDIO_VECTOR Velocity; // velocity vector in user-defined world units/second, used only for doppler calculations, does not affect Position

        UINT32 ChannelCount;       // number of sound channels, must be > 0
        FLOAT32 ChannelRadius;     // channel radius, used only with multi-channel emitters for matrix calculations, must be >= 0.0f when used
        FLOAT32* pChannelAzimuths; // channel azimuth array, used only with multi-channel emitters for matrix calculations, contains positions of each channel expressed in radians along the channel radius with respect to the front orientation vector in the plane orthogonal to the top orientation vector, or X3DAUDIO_2PI to specify a LFE channel, must have at least ChannelCount elements, all within [0.0f, X3DAUDIO_2PI] when used

        X3DAUDIO_DISTANCE_CURVE* pVolumeCurve;    // volume level distance curve, used only for matrix calculations, NULL specifies a default curve that conforms to the inverse square law with distances <= 1.0f clamped to no attenuation, CurveDistanceScaler is ignored when this parameter is NULL
        X3DAUDIO_DISTANCE_CURVE* pLFECurve;       // LFE level distance curve, used only for matrix calculations, NULL specifies a default curve that conforms to the inverse square law with distances <= 1.0f clamped to no attenuation, CurveDistanceScaler is ignored when this parameters is NULL
        X3DAUDIO_DISTANCE_CURVE* pLPFDirectCurve; // LPF direct-path coefficient distance curve, used only for LPF direct-path calculations, NULL specifies the default curve: [0.0f,1.0f], [1.0f,0.75f]
        X3DAUDIO_DISTANCE_CURVE* pLPFReverbCurve; // LPF reverb-path coefficient distance curve, used only for LPF reverb-path calculations, NULL specifies the default curve: [0.0f,0.75f], [1.0f,0.75f]
        X3DAUDIO_DISTANCE_CURVE* pReverbCurve;    // reverb send level distance curve, used only for reverb calculations, NULL specifies the default curve: [0.0f,1.0f], [1.0f,0.0f]

        FLOAT32 CurveDistanceScaler; // curve distance scaler, used to scale normalized distance curves to user-defined world units and/or exaggerate their effect, does not affect any other calculations, must be within [FLT_MIN, FLT_MAX] when used
        FLOAT32 DopplerScaler;       // doppler shift scaler, used to exaggerate doppler shift effect, does not affect any other calculations, must be within [0.0f, FLT_MAX] when used
    } X3DAUDIO_EMITTER, *LPX3DAUDIO_EMITTER;


    // DSP settings:
    // Receives results from a call to X3DAudioCalculate() to be sent
    // to the low-level audio rendering API for 3D signal processing.
    //
    // The user is responsible for allocating the matrix coefficient table,
    // delay time array, and initializing the channel counts when used.
    typedef struct X3DAUDIO_DSP_SETTINGS
    {
        FLOAT32* pMatrixCoefficients; // [in] matrix coefficient table, receives an array representing the volume level of each source channel present in each destination channel with the source channels being the column index and the destination channels being the row index of the table, must have at least SrcChannelCount*DstChannelCount elements
        FLOAT32* pDelayTimes;         // [in] delay time array, receives delays for each destination channel in milliseconds, must have at least DstChannelCount elements (stereo final mix only)
        UINT32 SrcChannelCount;       // [in] number of source channels, must equal number of channels on respective emitter
        UINT32 DstChannelCount;       // [in] number of destination channels, must equal number of channels on the final mix

        FLOAT32 LPFDirectCoefficient; // [out] LPF direct-path coefficient
        FLOAT32 LPFReverbCoefficient; // [out] LPF reverb-path coefficient
        FLOAT32 ReverbLevel; // [out] reverb send level
        FLOAT32 DopplerFactor; // [out] doppler shift factor, scales resampler ratio for doppler shift effect, where the effective frequency = DopplerFactor * original frequency
        FLOAT32 EmitterToListenerAngle; // [out] emitter-to-listener interior angle, expressed in radians with respect to the emitter's front orientation

        FLOAT32 EmitterToListenerDistance; // [out] distance in user-defined world units from the emitter base to listener position, always calculated
        FLOAT32 EmitterVelocityComponent; // [out] component of emitter velocity vector projected onto emitter->listener vector in user-defined world units/second, calculated only for doppler
        FLOAT32 ListenerVelocityComponent; // [out] component of listener velocity vector projected onto emitter->listener vector in user-defined world units/second, calculated only for doppler
    } X3DAUDIO_DSP_SETTINGS, *LPX3DAUDIO_DSP_SETTINGS;


//--------------<F-U-N-C-T-I-O-N-S>-----------------------------------------//
    // sets all global 3D audio constants
    X3DAUDIO_API_(void) X3DAudioInitialize (UINT32 SpeakerChannelMask, FLOAT32 SpeedOfSound, X3DAUDIO_HANDLE Instance);

    // calculates DSP settings with respect to 3D parameters
    X3DAUDIO_API_(void) X3DAudioCalculate (const X3DAUDIO_HANDLE Instance, const X3DAUDIO_LISTENER* pListener, const X3DAUDIO_EMITTER* pEmitter, UINT32 Flags, X3DAUDIO_DSP_SETTINGS* pDSPSettings);


#endif // __X3DAUDIO_H__
//---------------------------------<-EOF->----------------------------------//