[SDL] Re: Simulation timer with thread

[David Olofson]

On Tuesday 22 January 2002 21:43, Timo K Suoranta wrote:
[...]
> Now the actual question is that how should I synchronize the physics
> simulation with rendering? I do not want to slow down the physics
> simulation if the rendering is going too slow, but I am sure something
> could be done to improve the synchronization. Any ideas?

Kobo Deluxe does one of three things, depending on the control/rendering 
frame rate ratio:

	1. Control frame rate > rendering frame rate:
		The control system is called several times per
		rendered frame.

	2. Control frame rate == rendering frame rate:
		The control system is called once for each
		rendered frame.

	3. Control frame rate < rendering frame rate:
		Several frames are rendered for each control
		system frame.

Kobo Deluxe does not sleep, but just runs constantly, trying to pump out 
the maximum FPS - but that doesn't really matter. It would work just as 
well if an SDL_Delay(10) was inserted somewhere in the loop. (On targets 
with retrace sync, it would *possibly* run slower, while on systems 
without retrace sync, it *might* run smoother as a result of behaving 
nicer in the eyes of the OS scheduler.)


Now, unless the rendering code does some form of interpolation between 
the last two frames generated by the control system (as Kobo Deluxe does, 
in order to get the smoothest possible animation), there's obviously no 
point in rendering several video frames per control system frame in case 
3. Just go to sleep (SDL_Delay()), or do something else.


//David Olofson --- Programmer, Reologica Instruments AB

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