REF / Music API / Envelope
Anode . Modulator . Envelope
Songbook . Song . TimeKeeper
Voices . SampleMgr . StreamMgr
Loader . Async . Plot
Random . Rhythm . Util
MIDI . OSC . HID . Piano
Music Theory with Tonal
The purpose of
class Envelopeis to programmatically evaluate an LFO envelope function as used by Envelope Editor, Hz.LFO, and Hz.ModLFO
Envelope API
// To use the API, construct and initialize an instance of the class like so:
let myenv = new Envelope();
myenv.InitJSON(somejson);
// Next, invoke one of the evaluation method. Rinse and repeat.
let val = myenv.EvaluateOne(.5);
Here are the available methods.
| Method | Description |
|---|---|
Init(obj) |
Initialize from an object representation as produced by JSON.parse |
InitJSON(str) |
Parses the contents of a .knt or .vitallfo file |
EvaluateOne(t) |
Returns a value between 0 and 1 representing the envelope function at t (0-1) |
Render(npts) |
Returns an array of npts values representing the entire envelope. |
Envelope File Format (.knt)
The .knt file format is a single JSON object with these fields:
| Field | Description |
|---|---|
name |
string: describes the shape of the envelope |
smooth |
boolean: global smoothing |
data |
an array of triples representing t, y and power. Thus the number of knots is the length of this array divided by 3. t and y are (0-1) and power is (-5-5) |
prefs |
an optional object containing preview/sonification parameters |
Example .knt File
{
"name":"Weird Step",
"smooth":false,
"data":[
0,1,-3.401787519454956,
0.10631868243217468,0.017857134342193604,4.633926868438721,
0.3212454915046692,0.13214224576950073,-2.4107143878936768,
0.8373624086380005,1,0,
1,1,0
]
}