From 7dfbcf091880ab9d9ed24917f50e1b1920c6a811 Mon Sep 17 00:00:00 2001
From: jano <jean.pellotier@wanadoo.fr>
Date: Fri, 11 Dec 2020 23:11:58 +0100
Subject: [PATCH] Make the steady clock and MP clock init at modelHz boundary.
This removing any fractional (of a modelHz step) part when initialising.
This allow us to sync time in different FG instances, if FPS allow.
---
src/Time/TimeManager.cxx | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/src/Time/TimeManager.cxx b/src/Time/TimeManager.cxx
index 856adbcf0..1722ff72a 100644
--- a/src/Time/TimeManager.cxx
+++ b/src/Time/TimeManager.cxx
@@ -197,24 +197,31 @@ void TimeManager::valueChanged(SGPropertyNode* aProp)
void TimeManager::computeTimeDeltas(double& simDt, double& realDt)
{
- // Update the elapsed time.
- if (_firstUpdate) {
- _lastStamp.stamp();
+ const double modelHz = _modelHz->getDoubleValue();
- // we initialise the mp protocol clock with the system clock.
- _systemStamp.systemClockHoursAndMinutes();
- _steadyClock = _systemStamp.toSecs();
+ // Update the elapsed time.
+ if (_firstUpdate) {
+ _lastStamp.stamp();
- _firstUpdate = false;
- _lastClockFreeze = _clockFreeze->getBoolValue();
+ // Initialise the mp protocol / steady clock with the system clock.
+ // later, the clock follows steps of 1/modelHz (120 by default),
+ // so the MP clock remains aligned to these boundaries
+
+ _systemStamp.systemClockHoursAndMinutes();
+ const double systemStamp = _systemStamp.toSecs();
+ _steadyClock = floor(systemStamp * modelHz) / modelHz;
+
+ // initialize the remainder with offset from the system clock
+ _dtRemainder = systemStamp - _steadyClock;
+
+ _firstUpdate = false;
+ _lastClockFreeze = _clockFreeze->getBoolValue();
}
bool wait_for_scenery = !_sceneryLoaded->getBoolValue();
if (!wait_for_scenery) {
throttleUpdateRate();
- }
- else
- {
+ } else {
// suppress framerate while initial scenery isn't loaded yet (splash screen still active)
_lastFrameTime=0;
_frameCount = 0;
@@ -258,7 +265,6 @@ void TimeManager::computeTimeDeltas(double& simDt, double& realDt)
SGSubsystemGroup* fdmGroup =
globals->get_subsystem_mgr()->get_group(SGSubsystemMgr::FDM);
- double modelHz = _modelHz->getDoubleValue();
fdmGroup->set_fixed_update_time(1.0 / modelHz);
// round the real time down to a multiple of 1/model-hz.