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Wwise SDK 2018.1.11
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 released in source code form as part of the SDK installer package.

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 may use this file in accordance with the end user license agreement provided 

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 "Apache License"); you may not use this file except in compliance with the 

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   Version: <VERSION>  Build: <BUILDNUMBER>

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 // AkValueRamp.h

 /// \file 

 /// Linear interpolation services for plug-in parameters.

 #ifndef _AK_VALUERAMP_H_

 #define _AK_VALUERAMP_H_

 #include <AK/SoundEngine/Common/AkTypes.h>

 #include <AK/Tools/Common/AkAssert.h>

 #include <math.h>

 namespace AK

 {

     /// Platform-independent parameter interpolation service for software plug-ins.

     /// \aknote

     /// Algorithm performs linear interpolation.

     /// \endaknote

     /// \sa

     /// - \ref shared_parameter_interface

     class CAkValueRamp

     {

     public:

         /// Constructor method.

         CAkValueRamp() :

         m_fStepIncrement( 0.f ),    // Step increment sign

             m_fInc( 0.f ),          // Signed increment

             m_fTarget( 0.f ),       // Target gain for ramping

             m_fCurrent( 0.f ),      // Current interpolated value

             m_uRampCount( 0 ),      // Position in interpolation ramp

             m_uRampLength( 0 )      // Total duration of interpolation ramp

         {

         }

         /// Destructor method.

         ~CAkValueRamp()

         {

         }

         /// Initial parameter interpolation ramp setup.

         inline void RampSetup( 

             AkReal32 fStepIncrement,    ///< Increment to add to the parameter at every Tick() call

             AkReal32 fInitVal           ///< Initial ramp value

             )

         {

             AKASSERT( fStepIncrement > 0.f );

             m_fStepIncrement = fStepIncrement;

             m_fCurrent = fInitVal;

             SetTarget( fInitVal );

         }

         /// Set the ramp's target value.

         AkForceInline void SetTarget( 

             AkReal32 fTarget        ///< Target ramp value

             ) 

         {

             m_fTarget = fTarget;

             m_uRampCount = 0;

             AkReal32 fDiff = m_fTarget - m_fCurrent;

             m_uRampLength = static_cast<AkUInt32>( fabs(fDiff) / m_fStepIncrement );

             m_fInc = fDiff > 0 ? m_fStepIncrement : -m_fStepIncrement;

         }

         /// Process a single interpolation frame.

         /// \return The current interpolated value

         AkForceInline AkReal32 Tick()

         {

             if ( m_uRampCount >= m_uRampLength )

                 m_fCurrent = m_fTarget;

             else

             {

                 ++m_uRampCount;

                 m_fCurrent += m_fInc;

             }

             return m_fCurrent;

         }

         /// Retrieve the current interpolated value.

         /// \return The current interpolated value

         AkReal32 GetCurrent()                       { return m_fCurrent; }

         /// Set the current interpolated value.

         void SetCurrent(AkReal32 in_fCurrent)       { m_fCurrent = in_fCurrent; }

         /// Retrieve the current interpolation frame count.

         /// \return The current interpolation frame count

         AkUInt32 GetRampCount()                     { return m_uRampCount; }

         /// Set the current interpolation frame count.

         void SetRampCount(AkUInt32 in_uRampCount)   { m_uRampCount = in_uRampCount; }

         /// The ramp is no longer necessary; set to target

         void StopRamp()

         {

             m_fCurrent = m_fTarget;

             m_uRampCount = m_uRampLength;

         }

     private:

         AkReal32            m_fStepIncrement;       // Step increment size

         AkReal32            m_fInc;                 // Signed increment

         AkReal32            m_fTarget;              // Target for interpolation ramp

         AkReal32            m_fCurrent;             // Current interpolated value

         AkUInt32            m_uRampCount;           // Position in interpolation ramp

         AkUInt32            m_uRampLength;          // Total duration of interpolation ramp

     } AK_ALIGN_DMA;

 }

 #endif  //_AK_VALUERAMP_H_