Skip to content

Improve Timestep Algorithm #6898

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 4 commits into
base: master
Choose a base branch
from
Draft

Improve Timestep Algorithm #6898

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
0973dd6
average ideal sleep times rather than elapsed times
CoolSpy3 Oct 7, 2025
9a8de34
add lower bound to idealSleepTime
CoolSpy3 Oct 7, 2025
d65d478
use Qt::PreciseTimer and remove synchronization code
CoolSpy3 Oct 10, 2025
1c82c5e
include libwinpthread in distribution
CoolSpy3 Oct 11, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions scripts/packaging/files_msys64.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
/mingw64/bin/libpcre2-16-0.dll
/mingw64/bin/libpng16-16.dll
/mingw64/bin/libssl-3-x64.dll
/mingw64/bin/libwinpthread-1.dll
/mingw64/bin/Qt6Core.dll
/mingw64/bin/Qt6Gui.dll
/mingw64/bin/Qt6Network.dll
Expand Down
37 changes: 2 additions & 35 deletions src/webots/engine/WbSimulationWorld.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -73,8 +73,6 @@ WbSimulationWorld::WbSimulationWorld(WbTokenizer *tokenizer) :
}
}

mSleepRealTime = basicTimeStep();

WbPerformanceLog *log = WbPerformanceLog::instance();
if (log)
log->setTimeStep(basicTimeStep());
Expand Down Expand Up @@ -128,6 +126,7 @@ WbSimulationWorld::WbSimulationWorld(WbTokenizer *tokenizer) :
if (log)
log->stopMeasure(WbPerformanceLog::LOADING);

mTimer->setTimerType(Qt::PreciseTimer);
connect(mTimer, &QTimer::timeout, this, &WbSimulationWorld::triggerStepFromTimer);
const WbSimulationState *const s = WbSimulationState::instance();
connect(s, &WbSimulationState::rayTracingEnabled, this, &WbSimulationWorld::rayTracingEnabled);
Expand Down Expand Up @@ -185,37 +184,6 @@ void WbSimulationWorld::step() {

const double timeStep = basicTimeStep();

if (WbSimulationState::instance()->isRealTime()) {
const int elapsed = mRealTimeTimer.restart();

// computing the mean of an history of several elapsedTime
// improves significantly the stability of the algorithm
// in case of simulations where elapsedTime oscillates often
// above and below basicTimeStep.
// Moreover it improves the stability of simulations where
// basicTimeStep contains significant decimals
mElapsedTimeHistory.append(elapsed);
if (mElapsedTimeHistory.size() > qMax(4.0, 128.0 / timeStep)) // history size found empirically
mElapsedTimeHistory.pop_front();
double mean = 0.0;
foreach (const int &v, mElapsedTimeHistory)
mean += v;
mean /= mElapsedTimeHistory.size();

// useful hack: uncomment to run Webots at 90% of the real-time
// (if the real-time mode is enabled, of course)
// mean *= 0.90;

if (mean > timeStep && mSleepRealTime > 0.0) {
mSleepRealTime -= 0.03 * timeStep;
if (mSleepRealTime < 0)
mSleepRealTime = 0.0;
} else if (mean < timeStep)
mSleepRealTime += 0.03 * timeStep;

mTimer->start(mSleepRealTime);
}

emit physicsStepStarted();

if (log)
Expand Down Expand Up @@ -317,10 +285,9 @@ void WbSimulationWorld::modeChanged() {
WbSoundEngine::setMute(WbPreferences::instance()->value("Sound/mute").toBool());
break;
case WbSimulationState::REALTIME:
mRealTimeTimer.start();
WbSoundEngine::setPause(false);
WbSoundEngine::setMute(WbPreferences::instance()->value("Sound/mute").toBool());
mTimer->start(mSleepRealTime);
mTimer->start(basicTimeStep());
break;
case WbSimulationState::FAST:
WbSoundEngine::setPause(false);
Expand Down
3 changes: 0 additions & 3 deletions src/webots/engine/WbSimulationWorld.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -76,9 +76,6 @@ protected slots:
WbOdeContext *mOdeContext;
WbPhysicsPlugin *mPhysicsPlugin;
QTimer *mTimer;
QElapsedTimer mRealTimeTimer;
double mSleepRealTime;
QList<int> mElapsedTimeHistory;
QVector<WbNode *> mAddedNode; // list of nodes added since the simulation started

void storeLastSaveTime() override;
Expand Down