BansheeEngine/Documentation/Manuals/Native/User/time.md

Measuring time {#time}

Being able to tell the current time, as well as being able to tell elapsed time since the last frame is important for any real-time application. Use the @ref bs::Time "Time" class, accessible through @ref bs::gTime "gTime()" to retrieve global information about the time in Banshee.

Current time

Use @ref bs::Time::getTime() "Time::getTime()" to get the current time (since application start) in seconds.

float curTime = gTime().getTime();
gDebug().logDebug("Application was started " + toString(curTime) + " seconds ago.");

It's important to note this value is only updated once per frame (i.e. it stays constant throughout a frame). If you need more precise time that can be used for inter-frame measurements, use @ref bs::Time::getTimePrecise "Time::getTimePrecise()", which returns the current time in microseconds.

UINT64 preciseTimeStart = gTime().getTimePrecise();

UINT64 counter = 0;
for(int i = 0; i < 1000000; i++)
	counter += i % 10;

UINT64 preciseTimeEnd = gTime().getTimePrecise();
UINT64 timeElapsed = preciseTimeEnd - preciseTimeStart;

float secondsElapsed = timeElapsed * Time::MICROSEC_TO_SEC;
gDebug().logDebug("Operation took " + toString(secondsElapsed) + " seconds.");

@ref bs::Time::MICROSEC_TO_SEC "Time::MICROSEC_TO_SEC" is a constant to convert between microseconds and seconds.

You should use Time::getTime() for most gameplay purposes, while Time::getTimePrecise() can be used for profiling and other similar situations.

Elapsed time

Often it is useful to know know how much has passed since the last frame. Use @ref bs::Time::getFrameDelta() "Time::getFrameDelta()" to get the elapsed time from the previous frame.

float elapsedTime = gTime().getFrameDelta();
gDebug().logDebug("Last frame was " + toString(elapsedTime) + " seconds ago.");

Frame index

Sometimes, often for debugging purposes, it is useful to know the index of the current frame. Use @ref bs::Time::getFrameIdx() "Time::getFrameIdx()". Each frame the index gets incremented by one.

UINT64 frameIdx = gTime().getFrameIdx();
gDebug().logDebug("This is frame #" + toString(frameIdx));

Intervals

Sometimes it is useful to measure a time interval, like we did with Time::getTimePrecise() with the example above. You can also use the @ref bs::Timer "Timer" class for the same purpose, but with a slightly simpler interface.

Timer timer; // Starts counting

UINT64 counter = 0;
for(int i = 0; i < 1000000; i++)
	counter += i % 10;

float secondsElapsed = timer.getMicroseconds() * Time::MICROSEC_TO_SEC;
gDebug().logDebug("Operation took " + toString(secondsElapsed) + " seconds.");

Timer starts counting as soon as its constructed, and you can use @ref bs::Timer::getMicroseconds "Timer::getMicroseconds()" to retrieve the time elapsed.

Optionally you can also reset the timer by calling @ref bs::Timer::reset "Timer::reset()". This will set the time elapsed to 0, and any elapsed time will be reported from the last reset call.