From 8fc7688585cc8d95d1d5285ee20e2247bb72aa98 Mon Sep 17 00:00:00 2001
From: Raphael Forment <raphael.forment@gmail.com>
Date: Tue, 29 Aug 2023 13:46:43 +0200
Subject: [PATCH] envelopes on fmsynth

---
 packages/superdough/helpers.mjs | 13 +++++++++
 packages/superdough/synth.mjs   | 52 ++++++++++++++++++++++++++++-----
 2 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/packages/superdough/helpers.mjs b/packages/superdough/helpers.mjs
index 7cc54c8d..e07f0d7d 100644
--- a/packages/superdough/helpers.mjs
+++ b/packages/superdough/helpers.mjs
@@ -39,6 +39,19 @@ export const getEnvelope = (attack, decay, sustain, release, velocity, begin) =>
   };
 };
 
+export const getExpEnvelope = (attack, decay, velocity, begin) => {
+  const gainNode = getAudioContext().createGain();
+  gainNode.gain.setValueAtTime(0.0001, begin);
+  gainNode.gain.exponentialRampToValueAtTime(velocity, begin + attack);
+  gainNode.gain.exponentialRampToValueAtTime(0.0001, begin + attack + decay);
+  return {
+    node: gainNode,
+    stop: (t) => {
+      gainNode.gain.exponentialRampToValueAtTime(0.0001, t + decay);
+    },
+  };
+};
+
 export const getADSR = (attack, decay, sustain, release, velocity, begin, end) => {
   const gainNode = getAudioContext().createGain();
   gainNode.gain.setValueAtTime(0, begin);
diff --git a/packages/superdough/synth.mjs b/packages/superdough/synth.mjs
index 4ef9ddb8..fe389954 100644
--- a/packages/superdough/synth.mjs
+++ b/packages/superdough/synth.mjs
@@ -1,6 +1,6 @@
 import { midiToFreq, noteToMidi } from './util.mjs';
 import { registerSound, getAudioContext } from './superdough.mjs';
-import { getOscillator, gainNode, getEnvelope } from './helpers.mjs';
+import { getOscillator, gainNode, getEnvelope, getExpEnvelope } from './helpers.mjs';
 
 const mod = (freq, range = 1, type) => {
   const ctx = getAudioContext();
@@ -13,10 +13,38 @@ const mod = (freq, range = 1, type) => {
   return { node: g, stop: (t) => osc.stop(t) };
 };
 
-const fm = (osc, harmonicityRatio, modulationIndex, wave) => {
+const fm = (t, 
+	osc, 
+	harmonicityRatio, 
+	harmonicityAttack,
+	harmonicityDecay,
+	modulationIndex, 
+	modulationAttack,
+	modulationDecay,
+	wave, ) => {
+
   const carrfreq = osc.frequency.value;
-  const modfreq = carrfreq * harmonicityRatio;
-  const modgain = modfreq * modulationIndex;
+	let modfreq;
+	let modgain;
+
+	// Setting up envelopes if needed
+	if ((harmonicityAttack !== null) || (harmonicityDecay !== null)) {
+		let hattack = harmonicityAttack || 0.01;
+		let hdecay = harmonicityDecay || 0.5;
+		const harmonicEnv = getExpEnvelope(hattack, hdecay, 1, t);
+		modfreq = carrfreq * (harmonicityRatio * harmonicEnv);
+	} else {
+		modfreq = carrfreq * harmonicityRatio;
+	}
+	if ((modulationAttack !== null) || (modulationDecay !== null)) {
+		let mattack = modulationAttack || 0.01;
+		let mdecay = modulationDecay || 0.5;
+		const modulationEnv = getExpEnvelope(mattack, mdecay, 1, t);
+		modgain = modfreq * (modulationIndex * modulationEnv);
+	} else {
+		modgain = modfreq * modulationIndex;
+	}
+
   return mod(modfreq, modgain, wave);
 };
 
@@ -32,8 +60,12 @@ export function registerSynthSounds() {
           sustain = 0.6,
           release = 0.01,
           fmh: fmHarmonicity = 1,
+					fmhattack: fmHarmonicityAttack = null,
+					fmhdecay: fmHarmonicityDecay = null,
           fmi: fmModulationIndex,
-					fmwave: fmWaveform = 'sine'
+					fmiattack: fmModulationAttack = null,
+					fmidecay: fmModulationDecay = null,
+					fmwave: fmWaveform = 'sine',
         } = value;
         let { n, note, freq } = value;
         // with synths, n and note are the same thing
@@ -52,9 +84,15 @@ export function registerSynthSounds() {
         let stopFm;
         if (fmModulationIndex) {
           const { node: modulator, stop } = fm(
-						o, fmHarmonicity, 
+						t, 
+						o, 
+						fmHarmonicity, 
+						fmHarmonicityAttack,
+						fmHarmonicityDecay,
 						fmModulationIndex, 
-						fmWaveform
+						fmModulationAttack,
+						fmModulationDecay,
+						fmWaveform,
 					);
           modulator.connect(o.frequency);
           stopFm = stop;