[quote name='SimonForsman' timestamp='1335678100' post='4935764']
what do schedulers have to do with a fixed timestep ?
Say for example your physics engine runs at 50Hz, so 0.02s between executing physics. Due to the nature of a multitasking OS it won't be precisely 0.02s every time. One time it might be 0.018, another time 0.023. The difference may not be visible... or it may. Depending upon the nature of the physics and the speed of the objects involved. Also ignoring varying delta would be bad if there was a requirement for repeatability, such as in MMO games.
Using some game platforms the timing variation may be minimal, but some systems that I've tinkered with can have variations of up to 20%.
[/quote]
When you use a fixed timestep the delta is constant, you don't pass the actual elapsed time to the physics subsystem. (if you run the physics at 50hz with a fixed timestep you always pass 0.02 as the delta, if the elapsed time is 0.023 you still pass 0.02 as the delta and carry the 0.003 you have left (so the next update triggers after an additional 0.017s have passed), Therefore the scheduler has no impact on the simulation. (You can even run the simulation without measuring the actual elapsed time if the result doesn't have to be displayed in realtime (if you're making a movie for example))
If you need to compensate for a variable delta then you're not using a fixed timestep, you're using a variable timestep.
[size="1"]I don't suffer from insanity, I'm enjoying every minute of it.
The voices in my head may not be real, but they have some good ideas!