Home   Information   Classes   Download   Usage   Mail List   Requirements   Links   FAQ   Tutorial


Public Member Functions | List of all members
stk::Asymp Class Reference

STK asymptotic curve envelope class. More...

#include <Asymp.h>

Inheritance diagram for stk::Asymp:
stk::Generator stk::Stk

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). More...
 
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.
 
StkFramestick (StkFrames &frames, unsigned int channel=0)
 Fill a channel of the StkFrames object with computed outputs. More...
 
- 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 StkFrameslastFrame (void) const
 Return an StkFrames reference to the last output sample frame.
 
- 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. More...
 

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. More...
 
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.
 
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, 1995–2014.

Member Function Documentation

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.

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.

128 {
129 #if defined(_STK_DEBUG_)
130  if ( channel >= frames.channels() ) {
131  oStream_ << "Asymp::tick(): channel and StkFrames arguments are incompatible!";
132  handleError( StkError::FUNCTION_ARGUMENT );
133  }
134 #endif
135 
136  StkFloat *samples = &frames[channel];
137  unsigned int hop = frames.channels();
138  for ( unsigned int i=0; i<frames.frames(); i++, samples += hop )
139  *samples = Asymp::tick();
140 
141  return frames;
142 }

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

The Synthesis ToolKit in C++ (STK)
©1995--2014 Perry R. Cook and Gary P. Scavone. All Rights Reserved.