From 2acccf59c5b29295f8b1884276e20f4c736b3611 Mon Sep 17 00:00:00 2001
From: jbphet <john.blanco@colorado.edu>
Date: Tue, 23 Feb 2021 12:12:10 -0700
Subject: [PATCH] added prototype sound generator for wall charges, see #486

---
 .../model/WallModel.js                        |  4 +-
 .../view/WallNode.js                          | 38 ++++++++++++++++++-
 2 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/js/balloons-and-static-electricity/model/WallModel.js b/js/balloons-and-static-electricity/model/WallModel.js
index 09e7e764..68ea68cd 100644
--- a/js/balloons-and-static-electricity/model/WallModel.js
+++ b/js/balloons-and-static-electricity/model/WallModel.js
@@ -65,12 +65,12 @@ class WallModel {
     for ( let i = 0; i < this.numX; i++ ) {
       for ( let k = 0; k < this.numY; k++ ) {
 
-        //plus
+        // plus
         const position = this.calculatePosition( i, k );
         const plusCharge = new PointChargeModel( x + position[ 0 ], position[ 1 ], Tandem.OPT_OUT, false );
         this.plusCharges.push( plusCharge );
 
-        //minus
+        // minus
         const minusCharge = new MovablePointChargeModel(
           x + position[ 0 ] - PointChargeModel.RADIUS,
           position[ 1 ] - PointChargeModel.RADIUS,
diff --git a/js/balloons-and-static-electricity/view/WallNode.js b/js/balloons-and-static-electricity/view/WallNode.js
index a93a86ac..1e555f7d 100644
--- a/js/balloons-and-static-electricity/view/WallNode.js
+++ b/js/balloons-and-static-electricity/view/WallNode.js
@@ -6,15 +6,24 @@
  @author Vasily Shakhov (Mlearner)
  */
 
+import DerivedProperty from '../../../../axon/js/DerivedProperty.js';
 import Bounds2 from '../../../../dot/js/Bounds2.js';
+import Range from '../../../../dot/js/Range.js';
 import Image from '../../../../scenery/js/nodes/Image.js';
 import Node from '../../../../scenery/js/nodes/Node.js';
+import DiscreteSoundGenerator from '../../../../tambo/js/sound-generators/DiscreteSoundGenerator.js';
+import soundManager from '../../../../tambo/js/soundManager.js';
 import wallImage from '../../../images/wall_png.js';
 import balloonsAndStaticElectricity from '../../balloonsAndStaticElectricity.js';
 import BASEA11yStrings from '../BASEA11yStrings.js';
 import MinusChargesCanvasNode from './MinusChargesCanvasNode.js';
 import PlusChargeNode from './PlusChargeNode.js';
 import WallDescriber from './describers/WallDescriber.js';
+import chargeDeflectionSound from '../../../../tambo/sounds/release_mp3.js';
+// import chargeDeflectionSound from '../../../../tambo/sounds/grab_mp3.js';
+// import chargeDeflectionSound from '../../../../tambo/sounds/bright-marimba-short_mp3.js';
+// import chargeDeflectionSound from '../../../../tambo/sounds/slider-click-01_mp3.js';
+// import chargeDeflectionSound from '../../../../tambo/sounds/slider-click-01_mp3.js';
 
 const wallLabelString = BASEA11yStrings.wallLabel.value;
 
@@ -69,12 +78,39 @@ class WallNode extends Node {
       this.visible = isVisible;
     } );
 
-    //s how charges based on draw property
+    // show charges based on draw property
     model.showChargesProperty.link( value => {
       plusChargesNode.visible = ( value === 'all' );
       minusChargesNode.visible = ( value === 'all' );
     } );
 
+    // TODO: The following is a temporary prototype of sound generation for changes in the wall.  It's mostly a proof
+    //       of concept at this point, and will be replaced with something more thought out shortly.  See
+    //       https://github.com/phetsims/balloons-and-static-electricity/issues/486.
+    const nonDeflectedXPosition = model.wall.minusCharges[ 0 ].positionProperty.value.x;
+    const maxDeflectedXPosition = 739; // empirically determined
+
+    _.times( model.wall.numY, index => {
+      if ( index % 3 === 0 ){
+        const xPositionProperty = new DerivedProperty(
+          [ model.wall.minusCharges[ index ].positionProperty ],
+          positionVector => positionVector.x
+        );
+        const deflectionSoundGenerator = new DiscreteSoundGenerator(
+          xPositionProperty,
+          new Range( nonDeflectedXPosition, maxDeflectedXPosition ),
+          {
+            sound: chargeDeflectionSound,
+            playbackRateRange: new Range( 1, 2 ),
+            numBins: 15,
+            initialOutputLevel: 0.2,
+            outOfRangeValuesOK: true
+          }
+        );
+        soundManager.addSoundGenerator( deflectionSoundGenerator );
+      }
+    } );
+
     // pdom - when the balloons change position, update the description of the induced charge in the wall
     const updateWallDescription = () => {
       this.setDescriptionContent( this.wallDescriber.getWallDescription( model.yellowBalloon, model.greenBalloon, model.getBalloonsAdjacent() ) );