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Throttle Hz aligned to time-grid, add initial offset.

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Allows sync of two or more FG session, if wall clock are in synch.
This commit is contained in:
jano 2020-12-27 10:48:40 +01:00 committed by James Turner
parent 7dfbcf0918
commit a28bf28ee0
2 changed files with 24 additions and 11 deletions
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33
src/Time/TimeManager.cxx
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@ -116,6 +116,8 @@ void TimeManager::init()
_simTimeDelta = fgGetNode("sim/time/delta-sec", true);
_mpProtocolClockNode = fgGetNode("sim/time/mp-clock-sec", true);
_steadyClockNode = fgGetNode("sim/time/steady-clock-sec", true);
_frameTimeOffsetNode = fgGetNode("sim/time/frame-time-offset-ms", true);
_dtRemainderNode = fgGetNode("sim/time/dt-remainder-sec", true);
_mpClockOffset = fgGetNode("sim/time/mp-clock-offset-sec", true);
_steadyClockDrift = fgGetNode("sim/time/steady-clock-drift-ms", true);
_computeDrift = fgGetNode("sim/time/compute-clock-drift", true);
@ -150,6 +152,8 @@ void TimeManager::unbind()
_simTimeDelta.clear();
_mpProtocolClockNode.clear();
_steadyClockNode.clear();
_frameTimeOffsetNode.clear();
_dtRemainderNode.clear();
_mpClockOffset.clear();
_steadyClockDrift.clear();
_computeDrift.clear();
@ -211,6 +215,10 @@ void TimeManager::computeTimeDeltas(double& simDt, double& realDt)
const double systemStamp = _systemStamp.toSecs();
_steadyClock = floor(systemStamp * modelHz) / modelHz;
// add offset if defined
const double frameOffsetMsec = _frameTimeOffsetNode->getDoubleValue();
_steadyClock += frameOffsetMsec / 1000.0;
// initialize the remainder with offset from the system clock
_dtRemainder = systemStamp - _steadyClock;
@ -293,6 +301,7 @@ void TimeManager::computeTimeDeltas(double& simDt, double& realDt)
_steadyClock += mpProtocolDt;
_mpProtocolClock = _steadyClock + _mpClockOffset->getDoubleValue();
_dtRemainderNode->setDoubleValue(_dtRemainder);
_steadyClockNode->setDoubleValue(_steadyClock);
_mpProtocolClockNode->setDoubleValue(_mpProtocolClock);
@ -376,19 +385,21 @@ void TimeManager::computeFrameRate()
void TimeManager::throttleUpdateRate()
{
double throttle_hz = _maxFrameRate->getDoubleValue();
const double throttleHz = _maxFrameRate->getDoubleValue();
// no delay required.
if (throttleHz <= 0) {
_frameWait->setDoubleValue(0);
return;
}
// no delay required.
if (throttle_hz <= 0)
{
_frameWait->setDoubleValue(0);
return;
}
SGTimeStamp frameWaitStart = SGTimeStamp::now();
const double modelHz = _modelHz->getDoubleValue();
SGTimeStamp frameWaitStart = SGTimeStamp::now();
// sleep for exactly 1/hz seconds relative to the past valid timestamp
SGTimeStamp::sleepUntil(_lastStamp + SGTimeStamp::fromSec(1 / throttle_hz));
_frameWait->setDoubleValue(frameWaitStart.elapsedMSec());
// we want to sleep until just after the next ideal timestamp wanted, we will
// gain time from a 1/Hz step if the last timestamp was late.
const double t = (round(modelHz / throttleHz) / modelHz) - _dtRemainder;
SGTimeStamp::sleepUntil(_lastStamp + SGTimeStamp::fromSec(t));
_frameWait->setDoubleValue(frameWaitStart.elapsedMSec());
}
// periodic time updater wrapper

2
src/Time/TimeManager.hxx
View file

@ -91,6 +91,8 @@ private:
SGPropertyNode_ptr _simTimeFactor;
SGPropertyNode_ptr _mpProtocolClockNode;
SGPropertyNode_ptr _steadyClockNode;
SGPropertyNode_ptr _frameTimeOffsetNode;
SGPropertyNode_ptr _dtRemainderNode;
SGPropertyNode_ptr _mpClockOffset;
SGPropertyNode_ptr _steadyClockDrift;
SGPropertyNode_ptr _computeDrift;