stk::Asymp Class Reference

STK asymptotic curve envelope class. More...

#include <Asymp.h>

Inheritance diagram for stk::Asymp:

Public Member Functions
	Asymp (void)
	Default constructor.
	~Asymp (void)
	Class destructor.
void	keyOn (void)
	Set target = 1.
void	keyOff (void)
	Set target = 0.
void	setTau (StkFloat tau)
	Set the asymptotic rate via the time factor tau (must be > 0).
void	setTime (StkFloat time)
	Set the asymptotic rate based on a time duration (must be > 0).
void	setT60 (StkFloat t60)
	Set the asymptotic rate such that the target value is perceptually reached (to within -60dB of the target) in t60 seconds.
void	setTarget (StkFloat target)
	Set the target value.
void	setValue (StkFloat value)
	Set current and target values to value.
int	getState (void) const
	Return the current envelope state (0 = at target, 1 otherwise).
StkFloat	lastOut (void) const
	Return the last computed output value.
StkFloat	tick (void)
	Compute and return one output sample.
StkFrames &	tick (StkFrames &frames, unsigned int channel=0)
	Fill a channel of the StkFrames object with computed outputs.
Public Member Functions inherited from stk::Generator
	Generator (void)
	Class constructor.
unsigned int	channelsOut (void) const
	Return the number of output channels for the class.
const StkFrames &	lastFrame (void) const
	Return an StkFrames reference to the last output sample frame.
virtual StkFrames &	tick (StkFrames &frames, unsigned int channel=0)=0
	Fill the StkFrames object with computed sample frames, starting at the specified channel.
Public Member Functions inherited from stk::Stk
void	ignoreSampleRateChange (bool ignore=true)
	A function to enable/disable the automatic updating of class data when the STK sample rate changes.

Additional Inherited Members
Static Public Member Functions inherited from stk::Stk
static StkFloat	sampleRate (void)
	Static method that returns the current STK sample rate.
static void	setSampleRate (StkFloat rate)
	Static method that sets the STK sample rate.
static void	clear_alertList ()
	Static method that frees memory from alertList_.
static std::string	rawwavePath (void)
	Static method that returns the current rawwave path.
static void	setRawwavePath (std::string path)
	Static method that sets the STK rawwave path.
static void	swap16 (unsigned char *ptr)
	Static method that byte-swaps a 16-bit data type.
static void	swap32 (unsigned char *ptr)
	Static method that byte-swaps a 32-bit data type.
static void	swap64 (unsigned char *ptr)
	Static method that byte-swaps a 64-bit data type.
static void	sleep (unsigned long milliseconds)
	Static cross-platform method to sleep for a number of milliseconds.
static bool	inRange (StkFloat value, StkFloat min, StkFloat max)
	Static method to check whether a value is within a specified range.
static void	handleError (const char *message, StkError::Type type)
	Static function for error reporting and handling using c-strings.
static void	handleError (std::string message, StkError::Type type)
	Static function for error reporting and handling using c++ strings.
static void	showWarnings (bool status)
	Toggle display of WARNING and STATUS messages.
static void	printErrors (bool status)
	Toggle display of error messages before throwing exceptions.
Static Public Attributes inherited from stk::Stk
static const StkFormat	STK_SINT8
static const StkFormat	STK_SINT16
static const StkFormat	STK_SINT24
static const StkFormat	STK_SINT32
static const StkFormat	STK_FLOAT32
static const StkFormat	STK_FLOAT64
Protected Member Functions inherited from stk::Stk
	Stk (void)
	Default constructor.
virtual	~Stk (void)
	Class destructor.
virtual void	sampleRateChanged (StkFloat newRate, StkFloat oldRate)
	This function should be implemented in subclasses that depend on the sample rate.
void	addSampleRateAlert (Stk *ptr)
	Add class pointer to list for sample rate change notification.
void	removeSampleRateAlert (Stk *ptr)
	Remove class pointer from list for sample rate change notification.
void	handleError (StkError::Type type) const
	Internal function for error reporting that assumes message in oStream_ variable.

Detailed Description

STK asymptotic curve envelope class.

This class implements a simple envelope generator which asymptotically approaches a target value. The algorithm used is of the form:

y[n] = a y[n-1] + (1-a) target,

where a = exp(-T/tau), T is the sample period, and tau is a time constant. The user can set the time constant (default value = 0.3) and target value. Theoretically, this recursion never reaches its target, though the calculations in this class are stopped when the current value gets within a small threshold value of the target (at which time the current value is set to the target). It responds to keyOn and keyOff messages by ramping to 1.0 on keyOn and to 0.0 on keyOff.

by Perry R. Cook and Gary P. Scavone, 1995–2023.

Member Function Documentation

setTau()

void stk::Asymp::setTau

(

StkFloat

tau

)

Set the asymptotic rate via the time factor tau (must be > 0).

The rate is computed as described above. The value of tau must be greater than zero. Values of tau close to zero produce fast approach rates, while values greater than 1.0 produce rather slow rates.

tick()

StkFrames & stk::Asymp::tick ( StkFrames &  frames, unsigned int  channel = 0  )

inlinevirtual

Fill a channel of the StkFrames object with computed outputs.

The channel argument must be less than the number of channels in the StkFrames argument (the first channel is specified by 0). However, range checking is only performed if STK_DEBUG is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

Implements stk::Generator.

{
#if defined(_STK_DEBUG_)
  if ( channel >= frames.channels() ) {
    oStream_ << "Asymp::tick(): channel and StkFrames arguments are incompatible!";
    handleError( StkError::FUNCTION_ARGUMENT );
  }
#endif
 
  StkFloat *samples = &frames[channel];
  unsigned int hop = frames.channels();
  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
    *samples = Asymp::tick();
 
  return frames;
}

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The documentation for this class was generated from the following file:

• Asymp.h