Performing Calculations while Rendering

Jun 30, 2004 at 12:05 AM

This is my problem: When I have vsync off, my game loop runs at maximum speed, and my collision calculations are done ~150 times per second. When I turn vsync on, it slows down everything, and the calculations are only done 60 times per second, the collision calculations are less accurate. Should I disable vsync in code? Is there any way to have the rendering execute every 1/60 of a second (it should only take about 1/150), and then have the calculations done every 1/150 of a second? I would really appreciate some help with this. Thanks! -Shane

496

Jun 30, 2004 at 12:10 AM

dont force v-sync on or off, leave that upto the end user, its good maners [smile]

As to your problem you could flip the calculations out to a seperate thread, but that might not be the best path, someone else would have to advise here I think [smile]

the other option is to try and make them less dependant on being updated lots and try to make them more dependant on the time things collide.
However, again, someone else would have to help you here [smile]

202

Jun 30, 2004 at 12:11 AM

Please don't post about the same subject twice. There is enough advice on that thread.

Author

Jun 30, 2004 at 12:19 AM

LOL, you never actually answered my question though...
you instead asked why I was asking the question, which doesn't help anyone.

I guess I could make it more dependant on the time things collide - but wouldn't that expose the same problem?

There would still exist the issue of inaccurate calculations.

lonesock

Jun 30, 2004 at 12:25 AM

run your calculation loop multiple times per frame.

timeout = clock() + 12; // 16 ms for every frame at 60 hzwhile (clock() < timeout)  do_physics();

Author

Jun 30, 2004 at 12:31 AM

unfortunately, the problem with that is that the vsync slows down the loop - it seems like it is waiting for the next redraw governed by the monitor refresh rate. Is there any way to tell the program that it is done drawing, so that it continues the loop?

Thanks!

202

Jun 30, 2004 at 12:35 AM

If you have a proper timer callback, this shouldn't be affected by the Vsync or by the frame rate.

496

Jun 30, 2004 at 12:44 AM

same thing goes for shoving it in a thread on its own

Author