static AbsoluteTime frametime = {0, 0};
AbsoluteTime currTime = UpTime ();
double deltaTime = (float) AbsoluteDeltaToDuration (currTime, frametime);
static AbsoluteTime frametime = {0, 0};
AbsoluteTime currTime = UpTime ();
double deltaTime = (float) AbsoluteDeltaToDuration (currTime, frametime);