Report tiny values as 0

This prevents rounding errors caused by the use of floating point
values.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/ui/accelerometercontrol.cpp b/src/ui/accelerometercontrol.cpp
index 1a65afc..1ab7434 100644
--- a/src/ui/accelerometercontrol.cpp
+++ b/src/ui/accelerometercontrol.cpp
@@ -45,8 +45,11 @@ static QVector3D accelerometerY(0, 1, 0);
 static QVector3D accelerometerZ(0, 0, -1);
 static QVector3D unrotatedGravity(0, 1, 0);
 
+static const double kEarthGravity = 9.8;
+static const double kZero = 1e-4;
+
 AccelerometerControl::AccelerometerControl(QWidget *parent)
-    : QGLWidget(parent), mGravity(9.8)
+    : QGLWidget(parent), mGravity(kEarthGravity)
 {
 }
 
@@ -307,6 +310,10 @@ QVector3D AccelerometerControl::value() const
     newValue.setX(QVector3D::dotProduct(mRotation.conjugate().rotatedVector(accelerometerX), unrotatedGravity));
     newValue.setY(QVector3D::dotProduct(mRotation.conjugate().rotatedVector(accelerometerY), unrotatedGravity));
     newValue.setZ(QVector3D::dotProduct(mRotation.conjugate().rotatedVector(accelerometerZ), unrotatedGravity));
+    // remove rounding errors
+    if (qAbs(newValue.x()) < kZero) newValue.setX(0);
+    if (qAbs(newValue.y()) < kZero) newValue.setY(0);
+    if (qAbs(newValue.z()) < kZero) newValue.setZ(0);
     newValue *= mGravity;
 
     return newValue;