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std::chrono::hige_resolution_clock for timer?


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#1 Nanook   Members   -  Reputation: 505

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Posted 07 December 2012 - 04:37 PM

Can I use std::chrone::high_resolution_clock to get the time to calculate my fixed time step?

Or should I use the platform specific functions like QueryPerformanceCounter ?

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#2 frob   Moderators   -  Reputation: 21261

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Posted 07 December 2012 - 04:51 PM

If your compilers support C++11, feel free to use it. Otherwise, you will need to use the platform-specific functions.
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#3 Nanook   Members   -  Reputation: 505

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Posted 07 December 2012 - 04:55 PM

Right cool :)

All C++11 here.. :)

#4 VReality   Members   -  Reputation: 436

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Posted 07 December 2012 - 06:54 PM

Microsoft didn't use their performance counter in implementing C++11's high resolution clock. As a result it's not really high resolution and is probably an order of magnitude or so low for your frame timer. (See the bug report.)

You can test a clock's resolution by getting a time from it repeatedly until it returns a different time. Then you can decide for yourself if its resolution is sufficient for your purpose.

 

UPDATE: According to the notes (dated 11/13/2013) on the bug report linked above, this issue is still not fixed as of VC2013.

 

UPDATE: According to the notes (dated 3/17/2014) on the bug report linked above, this issue is should be fixed in the next major release (after VC2013).


Edited by VReality, 30 July 2014 - 07:07 AM.


#5 Ravyne   GDNet+   -  Reputation: 7373

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Posted 07 December 2012 - 08:07 PM

VReality, good to know. Microsoft just released (or maybe will soon) the first VS2012 update, so it might have been fixed already. I'll see if I can confirm that.

If not, in the meantime, OP can use QuerryPerformanceCounter, or boost::chrono, which uses QPC on Windows, as a work-around.

#6 Ravyne   GDNet+   -  Reputation: 7373

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Posted 07 December 2012 - 08:07 PM

VReality, good to know. Microsoft just released (or maybe will soon) the first VS2012 update, so it might have been fixed already. I'll see if I can confirm that.

If not, in the meantime, OP can use QuerryPerformanceCounter, or boost::chrono, which uses QPC on Windows, as a work-around.

#7 ApEk   Members   -  Reputation: 471

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Posted 08 December 2012 - 12:54 AM

In the event VS2012 actually supports std::chrono, here is a timer class that uses it. http://codepad.org/vVVA7qLC

#8 Trienco   Crossbones+   -  Reputation: 2172

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Posted 08 December 2012 - 01:02 AM

I'd definitely go with boost::chrono, since in theory once VS2012 has a working implementation it should be a simply matter of replacing boost with std.

Bit of frustrating, when I wanted to see how high-res that clock is and realized that all the clocks have the same resolution. Feels like one of this situation like "marketing wants to check off on that feature, so screw it if it works or not, just put something in there and let people file a bug report about it".
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#9 Nanook   Members   -  Reputation: 505

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Posted 08 December 2012 - 02:27 AM

Ah right.. that sucks.. I already have boost in my project so I'll use that for now..

#10 VReality   Members   -  Reputation: 436

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Posted 08 December 2012 - 07:57 AM

In the event VS2012 actually supports std::chrono, here is a timer class that uses it. http://codepad.org/vVVA7qLC


Just to be clear, VS2012 does provide the full std::chrono library.

However, the standard library is implemented individually on each platform. And VS2012 came with an implementation in which the high resolution clock is not really high resolution (has far less resolution than the performance counter provided by the hardware/OS).

Again, they have expressed the intention to fix this in the "out of band" release before the next version of VS. (see updates in my original post above).

Edited by VReality, 05 December 2013 - 02:55 AM.





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