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Alternative to Sleep() ?

For Beginners

Started by NextEpisode1 July 20, 2010 08:03 PM

18 comments, last by kburkhart84 13 years, 9 months ago

NextEpisode1

100

Author

July 20, 2010 08:03 PM

Hy , i did a small application where a sprite (player) moves around the screen using keys.

The animation is done by successive blit of images, i use Sleep() function to limit the player's speed (if i dont to that , you press a key and u are at the end of the screen in less than a second). The problem is that Sleep() not only delays the animation but also the msg processing and the window is not processing anything until the animation loop is done executing (getting from point A to point B)

Any hints how can i fix that?

#include <iostream>#include <string>int main(){ std::cout<<"I will kill your stack"; return main();}

Hodgman

52,717

July 20, 2010 08:09 PM

You're using a very basic "frame limiter", which just wastes time (sleeps) so the frame rate can't get too high. These systems are fraught with a lot of problems.

It's much better to actually measure the amount of time that each frame has taken, and either:
*Use this time value to run your 'Update' code a variable number of times per frame.
and/or
*Use this time value as a multiplier on your movement speeds -- e.g. position += speed * elapsedTime

. 22 Racing Series .

Chadwell

130

July 20, 2010 11:02 PM

As Hodgman said, use the elapsed time to calculate changes in your game objects. Here is a great article about time steps(and physics) if you are interested...

http://gafferongames.com/game-physics/fix-your-timestep/

Also, adding a small sleep call to your loop isn't necessarily bad. A sleep call small enough that it won't inhibit your run time performance will help reduce cpu usage and allow other tasks to get processor time on single processor systems.

NextEpisode1

100

Author

July 21, 2010 12:37 PM

Quote:Original post by Hodgman
You're using a very basic "frame limiter", which just wastes time (sleeps) so the frame rate can't get too high. These systems are fraught with a lot of problems.

It's much better to actually measure the amount of time that each frame has taken, and either:
*Use this time value to run your 'Update' code a variable number of times per frame.
and/or
*Use this time value as a multiplier on your movement speeds -- e.g. position += speed * elapsedTime

thanks , i'v implemented that , works like clockwork.

#include <iostream>#include <string>int main(){ std::cout<<"I will kill your stack"; return main();}

NextEpisode1

100

Author

July 21, 2010 12:37 PM

Quote:Original post by Chadwell
As Hodgman said, use the elapsed time to calculate changes in your game objects. Here is a great article about time steps(and physics) if you are interested...

http://gafferongames.com/game-physics/fix-your-timestep/

Also, adding a small sleep call to your loop isn't necessarily bad. A sleep call small enough that it won't inhibit your run time performance will help reduce cpu usage and allow other tasks to get processor time on single processor systems.

thanks for the reference

#include <iostream>#include <string>int main(){ std::cout<<"I will kill your stack"; return main();}

BTownTKD

205

July 21, 2010 12:44 PM

P.S. NextEpisode1:

Your signature won't compile...

Deep Blue Wave - Brian's Dev Blog.

boogyman19946

1,487

July 21, 2010 12:47 PM

^ I believe you're missing a return statement :D

Yo dawg, don't even trip.

nobodynews

3,128

July 21, 2010 12:49 PM

Quote:Original post by BTownTKD
P.S. NextEpisode1:

Your signature won't compile...

I don't see any errors in his signature. I haven't actually tried compiling it though so I could have missed something.

C++: A Dialog | C++0x Features: Part1 (lambdas, auto, static_assert) , Part 2 (rvalue references) , Part 3 (decltype) | Write Games | Fix Your Timestep!