From 75a6d51ac8c8fab3f2aa648bddea5a59146bb65a Mon Sep 17 00:00:00 2001
From: Jordan Santell <jordan@jsantell.com>
Date: Mon, 5 Mar 2018 09:31:54 -0800
Subject: [PATCH] Handle Chrome m66+'s change of reporting a deviceorientation
 rotationRate in degrees, rather than (incorrect) radians. Fixes #18

---
 src/sensor-fusion/fusion-pose-sensor.js | 10 +++++++---
 src/util.js                             | 12 ++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/sensor-fusion/fusion-pose-sensor.js b/src/sensor-fusion/fusion-pose-sensor.js
index 161f43e..3a970a3 100644
--- a/src/sensor-fusion/fusion-pose-sensor.js
+++ b/src/sensor-fusion/fusion-pose-sensor.js
@@ -62,6 +62,10 @@ function FusionPoseSensor(kFilter, predictionTime, yawOnly, isDebug) {
 
   this.isFirefoxAndroid = Util.isFirefoxAndroid();
   this.isIOS = Util.isIOS();
+  // Chrome as of m66 started reporting `rotationRate` in degrees rather
+  // than radians, to be consistent with other browsers.
+  // https://github.com/immersive-web/cardboard-vr-display/issues/18
+  this.isChromeUsingDegrees = Util.getChromeVersion() >= 66;
 
   this.orientationOut_ = new Float32Array(4);
 }
@@ -153,9 +157,9 @@ FusionPoseSensor.prototype.updateDeviceMotion_ = function(deviceMotion) {
     this.gyroscope.set(rotRate.alpha, rotRate.beta, rotRate.gamma);
   }
 
-  // With iOS and Firefox Android, rotationRate is reported in degrees,
-  // so we first convert to radians.
-  if (this.isIOS || this.isFirefoxAndroid) {
+  // Browsers on iOS, Firefox/Android, and Chrome m66/Android `rotationRate`
+  // is reported in degrees, so we first convert to radians.
+  if (this.isIOS || this.isFirefoxAndroid || this.isChromeUsingDegrees) {
     this.gyroscope.multiplyScalar(Math.PI / 180);
   }
 
diff --git a/src/util.js b/src/util.js
index 3464d6e..52fd2e2 100644
--- a/src/util.js
+++ b/src/util.js
@@ -59,6 +59,18 @@ export const isFirefoxAndroid = (function() {
   };
 })();
 
+/**
+ * Returns a number value indiciating the version of Chrome being used,
+ * or otherwise `null` if not on Chrome.
+ */
+export const getChromeVersion = (function() {
+  const match = navigator.userAgent.match(/.*Chrome\/([0-9]+)/);
+  const value = match ? parseInt(match[1], 10) : null;
+  return function() {
+    return value;
+  };
+})();
+
 export const isR7 = (function() {
   var isR7 = navigator.userAgent.indexOf('R7 Build') !== -1;
   return function() {