From 7a14410a282f76b392eaff1ba2651b820aeb24a4 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Tue, 11 Nov 2014 13:22:27 +0100
Subject: sane gimbal lock bounds

Tested-by: @KyokushinPL
Issue: #63
---
 opentrack/tracker.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/opentrack/tracker.cpp b/opentrack/tracker.cpp
index 5b36971e..07ea22b5 100644
--- a/opentrack/tracker.cpp
+++ b/opentrack/tracker.cpp
@@ -53,12 +53,13 @@ static dmat<3, 1> rmat_to_euler(const dmat<3, 3>& R)
 {
     static constexpr double pi = 3.141592653;
     const double up = 90 * pi / 180.;
-    if (R(0, 2) > 0.998)
+    static constexpr double bound = 1. - 2e-4;
+    if (R(0, 2) > bound)
     {
         double roll = atan(R(1, 0) / R(2, 0));
         return dmat<3, 1>({0., up, roll});
     }
-    if (R(0, 2) < -0.998)
+    if (R(0, 2) < -bound)
     {
         double roll = atan(R(1, 0) / R(2, 0));
         return dmat<3, 1>({0., -up, roll});
-- 
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