Fix the jump of Yaw and Roll when crossing the border +/-180 degrees

When crossing the border on Yaw or Roll +/-180 degrees, the Octopus makes a full rotation of 360 degrees. This made it difficult to use an inertial tracker in a wireless VR.

1 files changed, 4 insertions, 0 deletions

diff --git a/filter-accela/ftnoir_filter_accela.cpp b/filter-accela/ftnoir_filter_accela.cpp
index 44a341e0..2059d7f9 100644
--- a/filter-accela/ftnoir_filter_accela.cpp
+++ b/filter-accela/ftnoir_filter_accela.cpp
@@ -64,6 +64,8 @@ static void do_deltas(const double* deltas, double* output, F&& fun)
 
 void accela::filter(const double* input, double *output)
 {
+#define FULL_TURN 360.0
+#define HALF_TURN 180.0
     if (unlikely(first_run))
     {
         first_run = false;
@@ -98,6 +100,7 @@ void accela::filter(const double* input, double *output)
     for (unsigned i = 3; i < 6; i++)
     {
         double d = input[i] - last_output[i];
+		if (fabs(d) > HALF_TURN) d -= copysign(FULL_TURN, d);
 
         if (fabs(d) > rot_dz)
             d -= copysign(rot_dz, d);
@@ -134,6 +137,7 @@ void accela::filter(const double* input, double *output)
     {
         output[k] *= dt;
         output[k] += last_output[k];
+		if (fabs(output[k]) > HALF_TURN) output[k] -= copysign(FULL_TURN, output[k]);
 
         last_output[k] = output[k];
     }