From 1221c6144ca314fb3e80766f89b8bb93cb1a6b0d Mon Sep 17 00:00:00 2001
From: "Jade (Rose) Rowland" <jaderowlanddev@gmail.com>
Date: Wed, 28 Feb 2024 14:31:07 -0500
Subject: [PATCH] added distortion effect

---
 packages/core/controls.mjs         | 22 +++++++++++++++++-----
 packages/superdough/superdough.mjs | 11 +++++++++--
 packages/superdough/worklets.mjs   | 28 +++++++++++++++++++++++++++-
 3 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/packages/core/controls.mjs b/packages/core/controls.mjs
index c034f1b5..42f4648a 100644
--- a/packages/core/controls.mjs
+++ b/packages/core/controls.mjs
@@ -1214,19 +1214,31 @@ const generic_params = [
   // ['sclaves'],
   // ['scrash'],
   /**
-   * Wave shaping distortion. CAUTION: it might get loud
+   * (Deprecated) Wave shaping distortion. WARNING: can suddenly get unpredictably loud.
+   * Please use distort instead, which has a more predictable response curve
    * second option in optional array syntax (ex: ".9:.5") applies a postgain to the output
-   * most useful shape values are usually between 0 and 10 (depending on source gain)
    *
    * @name shape
    * @param {number | Pattern} distortion between 0 and 1
    * @example
-   * s("bd sd [~ bd] sd,hh*8").shape("<0 2 3 10:.5>")
-   * @example
-   * note("d1!8").s("sine").penv(36).pdecay(.12).decay(.23).shape("8:.4")
+   * s("bd sd [~ bd] sd,hh*8").shape("<0 .2 .3 .95:.5>")
    *
    */
   ['shape'],
+
+  /**
+   * Wave shaping distortion. CAUTION: it can get loud.
+   * Second option in optional array syntax (ex: ".9:.5") applies a postgain to the output.
+   * Most useful values are usually between 0 and 10 (depending on source gain). If you are feeling adventurous, you can turn it up to 11 and beyond ;)
+   * @name distort
+   * @param {number | Pattern} distortion
+   * @example
+   * s("bd sd [~ bd] sd,hh*8").distort("<0 2 3 10:.5>")
+   * @example
+   * note("d1!8").s("sine").penv(36).pdecay(.12).decay(.23).distort("8:.4")
+   *
+   */
+  ['distort', 'dist'],
   /**
    * Dynamics Compressor. The params are `compressor("threshold:ratio:knee:attack:release")`
    * More info [here](https://developer.mozilla.org/en-US/docs/Web/API/DynamicsCompressorNode?retiredLocale=de#instance_properties)
diff --git a/packages/superdough/superdough.mjs b/packages/superdough/superdough.mjs
index 2eb42720..795354ad 100644
--- a/packages/superdough/superdough.mjs
+++ b/packages/superdough/superdough.mjs
@@ -311,6 +311,7 @@ export const superdough = async (value, deadline, hapDuration) => {
     coarse,
     crush,
     shape,
+    distort,
     pan,
     vowel,
     delay = 0,
@@ -452,8 +453,14 @@ export const superdough = async (value, deadline, hapDuration) => {
   // effects
   coarse !== undefined && chain.push(getWorklet(ac, 'coarse-processor', { coarse }));
   crush !== undefined && chain.push(getWorklet(ac, 'crush-processor', { crush }));
-  const shapeInput = Array.isArray(shape) ? { shape: shape[0], postgain: shape[1] } : { shape };
-  shape !== undefined && chain.push(getWorklet(ac, 'shape-processor', shapeInput));
+  if (shape !== undefined) {
+    const input = Array.isArray(shape) ? { shape: shape[0], postgain: shape[1] } : { shape };
+    chain.push(getWorklet(ac, 'shape-processor', input));
+  }
+  if (distort !== undefined) {
+    const input = Array.isArray(distort) ? { distort: distort[0], postgain: distort[1] } : { distort };
+    chain.push(getWorklet(ac, 'distort-processor', input));
+  }
 
   compressorThreshold !== undefined &&
     chain.push(
diff --git a/packages/superdough/worklets.mjs b/packages/superdough/worklets.mjs
index 25885ce6..3f6d7ac9 100644
--- a/packages/superdough/worklets.mjs
+++ b/packages/superdough/worklets.mjs
@@ -75,7 +75,8 @@ class ShapeProcessor extends AudioWorkletProcessor {
   process(inputs, outputs, parameters) {
     let shape = parameters.shape[0];
     const postgain = Math.max(0.001, Math.min(1, parameters.postgain[0]));
-    shape = Math.expm1(shape * 5);
+    shape = shape < 1 ? shape : 1.0 - 4e-10;
+    shape = (2.0 * shape) / (1.0 - shape);
     return processSample(inputs, outputs, (block) => {
       const val = ((1 + shape) * block) / (1 + shape * Math.abs(block));
       return val * postgain;
@@ -84,3 +85,28 @@ class ShapeProcessor extends AudioWorkletProcessor {
 }
 
 registerProcessor('shape-processor', ShapeProcessor);
+
+class DistortProcessor extends AudioWorkletProcessor {
+  static get parameterDescriptors() {
+    return [
+      { name: 'distort', defaultValue: 0 },
+      { name: 'postgain', defaultValue: 1 },
+    ];
+  }
+
+  constructor() {
+    super();
+  }
+
+  process(inputs, outputs, parameters) {
+    let shape = parameters.distort[0];
+    const postgain = Math.max(0.001, Math.min(1, parameters.postgain[0]));
+    shape = Math.expm1(shape);
+    return processSample(inputs, outputs, (block) => {
+      const val = ((1 + shape) * block) / (1 + shape * Math.abs(block));
+      return val * postgain;
+    });
+  }
+}
+
+registerProcessor('distort-processor', DistortProcessor);