From 24a618bf0b975b0c9aae19544ba5fb9d60d309a6 Mon Sep 17 00:00:00 2001
From: jberg <jberg@users.noreply.github.com>
Date: Tue, 14 Aug 2018 18:46:03 -0700
Subject: [PATCH] fix oscilloscope amplitude and direction (#629)

---
 js/components/Visualizer.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/js/components/Visualizer.js b/js/components/Visualizer.js
index 67b0d807..33ca70a7 100644
--- a/js/components/Visualizer.js
+++ b/js/components/Visualizer.js
@@ -226,8 +226,8 @@ class Visualizer extends React.Component {
     // Iterate over the width of the canvas in "real" pixels.
     for (let j = 0; j <= this._renderWidth(); j++) {
       const amplitude = sliceAverage(this.dataArray, sliceWidth, j);
-      const percentAmplitude = (amplitude - 128) / 128; // dataArray gives us bytes
-      const y = percentAmplitude * h + h / 2; // center wave at half height
+      const percentAmplitude = amplitude / 255; // dataArray gives us bytes
+      const y = (1 - percentAmplitude) * h; // flip y
       const x = j * PIXEL_DENSITY;
 
       // Canvas coordinates are in the middle of the pixel by default.