diff stk/include/Envelope.h @ 0:4606bd505630 tip

first import

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/stk/include/Envelope.h	Sat Jun 13 15:08:10 2015 +0100
@@ -0,0 +1,130 @@
+#ifndef STK_ENVELOPE_H
+#define STK_ENVELOPE_H
+
+#include "Generator.h"
+
+namespace stk {
+
+/***************************************************/
+/*! \class Envelope
+    \brief STK linear line envelope class.
+
+    This class implements a simple linear line envelope generator
+    which is capable of ramping to an arbitrary target value by a
+    specified \e rate.  It also responds to simple \e keyOn and \e
+    keyOff messages, ramping to 1.0 on keyOn and to 0.0 on keyOff.
+
+    by Perry R. Cook and Gary P. Scavone, 1995--2014.
+*/
+/***************************************************/
+
+class Envelope : public Generator
+{
+ public:
+
+  //! Default constructor.
+  Envelope( void );
+
+  //! Class destructor.
+  ~Envelope( void );
+
+  //! Assignment operator.
+  Envelope& operator= ( const Envelope& e );
+
+  //! Set target = 1.
+  void keyOn( void ) { this->setTarget( 1.0 ); };
+
+  //! Set target = 0.
+  void keyOff( void ) { this->setTarget( 0.0 ); };
+
+  //! Set the \e rate.
+  /*!
+    The \e rate must be positive (though a value of 0.0 is allowed).
+   */
+  void setRate( StkFloat rate );
+
+  //! Set the \e rate based on a positive time duration (seconds).
+  /*!
+    The \e rate is calculated such that the envelope will ramp from
+    a value of 0.0 to 1.0 in the specified time duration.
+   */
+  void setTime( StkFloat time );
+
+  //! Set the target value.
+  void setTarget( StkFloat target );
+
+  //! Set current and target values to \e value.
+  void setValue( StkFloat value );
+
+  //! Return the current envelope \e state (0 = at target, 1 otherwise).
+  int getState( void ) const { return state_; };
+
+  //! Return the last computed output value.
+  StkFloat lastOut( void ) const { return lastFrame_[0]; };
+
+  //! Compute and return one output sample.
+  StkFloat tick( void );
+
+  //! Fill a channel of the StkFrames object with computed outputs.
+  /*!
+    The \c 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.
+  */
+  StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
+
+ protected:
+
+  void sampleRateChanged( StkFloat newRate, StkFloat oldRate );
+
+  StkFloat value_;
+  StkFloat target_;
+  StkFloat rate_;
+  int state_;
+};
+
+inline StkFloat Envelope :: tick( void )
+{
+  if ( state_ ) {
+    if ( target_ > value_ ) {
+      value_ += rate_;
+      if ( value_ >= target_ ) {
+        value_ = target_;
+        state_ = 0;
+      }
+    }
+    else {
+      value_ -= rate_;
+      if ( value_ <= target_ ) {
+        value_ = target_;
+        state_ = 0;
+      }
+    }
+    lastFrame_[0] = value_;
+  }
+
+  return value_;
+}
+
+inline StkFrames& Envelope :: tick( StkFrames& frames, unsigned int channel )
+{
+#if defined(_STK_DEBUG_)
+  if ( channel >= frames.channels() ) {
+    oStream_ << "Envelope::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 = tick();
+
+  return frames;
+}
+
+} // stk namespace
+
+#endif