Home   Information   Classes   Download   Usage   Mail List   Requirements   Links   FAQ   Tutorial


stk::Asymp Class Reference

STK asymptotic curve envelope class. More...

#include <Asymp.h>

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

List of all members.

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 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.

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 - 2010.


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 
) [inline, virtual]

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.


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

The Synthesis ToolKit in C++ (STK)
©1995-2010 Perry R. Cook and Gary P. Scavone. All Rights Reserved.