// name: adsr.ck// desc: an ADSR envelope describes how a sound changes over time.//       It's often used in music synthesis to control the volume of//       a sound. ADSR stands for Attack, Decay, Sustain, and Release.//       Each of these terms describes a different part of the sound's//       volume over time. In this example, an ADSR is used to shape//       a continuous sine wave into individual notes.////          /\//         /  \_____//        /         \//       The general shape of a ADSR envelope.////       (A)ttack: This is the initial burst of sound when a note is//       played. It's how quickly the volume reaches its maximum level.////       (D)ecay: After the attack, the sound level will decrease over//       time to a lower level. The decay time is how long it takes for//       the sound to reach the sustain level.////       (S)ustain: This is the steady state of the sound after the//       initial attack and decay. The sound remains at a constant level//       as long as the note is held down.////       (R)elease: When the note is released, the sound level will drop//       back down to zero. The release time is how long it takes for the//       sound to fade away completely.////       for more info on envelopes and ADSRs see://           https://en.wikipedia.org/wiki/Envelope_(music)#ADSR // our patchSinOsc s => ADSR e => dac; // set A, D, S, and Re.set( 10::ms, 8::ms, .5, 500::ms );// (note: A, D, R are durations; S is a number between 0 and 1) // set gain.5 => s.gain; // infinite time-loopwhile( true ){    // choose freq    Math.random2( 32, 96 ) => Std.mtof => s.freq;     // key on: begin ATTACK    // (note: ATTACK automatically transitions to DECAY;    //        DECAY automatically transitions to SUSTAIN)    e.keyOn();    // advance time by 500 ms    // (note: this is the duration from the    //        beginning of ATTACK to the end of SUSTAIN)    500::ms => now;    // key off; start RELEASE    e.keyOff();    // allow the RELEASE to ramp down to 0    e.releaseTime() => now;     // advance time by 300 ms (duration until the next sound)    300::ms => now;}