Physics Engine & control input frequency to lock max frames to (or multiples of 60)

Discussion in 'General Discussion' started by Spinelli, Jul 18, 2012.

  1. Spinelli

    Spinelli Banned

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    .
    For rFactor 1

    The core engine - the physics engine - runs at 400 hz regardless of your framerate. The physics engine is updated by your control input at 100 hz and that's why having the game locked at minimum 100 fps (or to help with screen tearing multiples of 60 over it like 120, 180 etc) will offer optimal feel and precision with regards to your inputs to the game, input lag, etc etc.

    When I set my frames in rFactor 1 to make sure to never drop below 100 (and I set max in plr to -120 so that for the most part the frames are glued on 120) I gotta say it made a huge difference in steering feel. Big difference over even 60. Everything was so much sharper, direct, instant. The max 120 also really helped with the overall smoothness stutters and tearing (negative value seems to work better than postitive value aswell). I heard 180 is even better but it will just be a tiny tiny difference from 120 and 120 is pretty much optimal.

    Now what are these 2 numbers for rF2? Are they still 400 and 100? Someone told me they are now 500 and 100...?


    It starts getting interesting as of about post 9, here is the link

    http://www.nogripracing.com/forum/showthread.php?p=1100224

    One user replied...

    "Control precision will increase as your frame rates increase, up to 100 fps. Anything over that isn't going to improve the precision of the controls, because they will not refresh faster than 100Hz.
    For the truest feel, 100fps is desired, since it matches the controls frequency.

    In other words, 100fps will put your game in sync with the 100Hz controls frequency, giving you the optimal relationship between game and controls. Less than 100fps, and there will be some lag. The further from 100fps the worse it will become. Anything over 100fps is overkill, since 100Hz is all the controls are going to refresh at anyway."
     
    Last edited by a moderator: Jul 18, 2012
  2. MaXyM

    MaXyM Registered

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    For me there is no difference between 80 and 180fps. I would like to be so sensitive so you are. Or maybe... I should be thankful I'm not ;)

    As far as I know rF2 has physics engine separated, clocked independently from gfx. But why do you want to know details? To start feel the differences? ;)
     
  3. KeiKei

    KeiKei Registered

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    I'm just wondering how the sim would be with 120 Hz monitor and 120 FPS?
     
  4. Adrianstealth

    Adrianstealth Registered

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    This is interesting I never knew anything about this

    Anymore info from those in the know appreciated
     
  5. osella

    osella Registered

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    I've heard about this too but I still don't get it.
    Since the physics engine is updated by your input at 100Hz regardless of your fps, how does 60 vs 100 can make any difference, if LCD is only 60Hz?
    I'll try to focus on it in the evening if I see any difference but from my memory I don't remember more sharper response when playing on some simple track with 200fps compared to targa where I have just over 60...
     
  6. Spinelli

    Spinelli Banned

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    I want to know so that I know what frame rate to aim for, rfactor 1 is anything over 100fps as the control input frequency is 100 hertz. So I would like to know this value for rfactor 2.
     
  7. Adrianstealth

    Adrianstealth Registered

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    "Physics updated by input"

    Dosnt the physics update so many times per second based on what the car is doing (which is obviously effected by input)
    What I mean to say isn't the update rate (of the physics) fixed?
     
  8. Spinelli

    Spinelli Banned

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    No, the physics engine in rFactor 1 is apparently updated at 400 hz regardless of your framerate. The control input is updated at "over 100 hz" according to ISI, it doesnt say it is regardless of your fps, thats only for the core physics that is regardless of your fps, not the user control input.

    No because ISI put the core physics frequency in a seperate thread from the control input, this change was I think done in Version 1.250..




    Ill send you guys the link to the thread I first read it on. It starts getting interesting as of post #9

    http://www.nogripracing.com/forum/showthread.php?p=1100224

    One user replied...

    "Control precision will increase as your frame rates increase, up to 100 fps. Anything over that isn't going to improve the precision of the controls, because they will not refresh faster than 100Hz.
    For the truest feel, 100fps is desired, since it matches the controls frequency.

    In other words, 100fps will put your game in sync with the 100Hz controls frequency, giving you the optimal relationship between game and controls. Less than 100fps, and there will be some lag. The further from 100fps the worse it will become. Anything over 100fps is overkill, since 100Hz is all the controls are going to refresh at anyway."
     
    Last edited by a moderator: Jul 18, 2012
  9. ZeosPantera

    ZeosPantera Registered

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    We are talking about refreshes per second. 400 times for physics and 100 times for input is more than enough. The actual framerate is just the amount of info YOU are receiving per second and frankly display lag is a far more important issue and no, 120Hz displays don't fix THIS issue.



    And people wonder why I use giant CRT's.
     
  10. MaXyM

    MaXyM Registered

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    'Cause CRTs have minimum display lag comparing to LCD :)
     
  11. Spinelli

    Spinelli Banned

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    Display input lag is brutal, thank god I have one of the lowest display input lag monitors ever, Samsung PX2370 3.3 ms. Supposedly anything under 16ms is fine as that is one frame, you are starting to see more and more lately that are at 5-9ish, unfortunately most if not all are tft not ips. Also most seem to be 60hz not 120hz which seems odd (maybe 120hz requires more processing/post processing?).

    Anyways back to the original topic, does anyone know what the control refersh rate of the rFactor2 engine is set at ( I heard the physics engine is set at 400 - 500hz but I am wondering about the control input frquency aka controller refresh rate).
     
  12. ZeosPantera

    ZeosPantera Registered

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    Well shouldn't that be limited to your USB polling rate?
     
  13. Spinelli

    Spinelli Banned

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    Please read original post and the thread link,
     
  14. TechAde

    TechAde Registered

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    One of the patches for rF1 added de-coupling of the input polling rate from the frame rate via the Controller.ini entry Fixed Rate Inputs="1" // whether to sample joystick/wheel inputs in a thread for better precision.

    In rF2 I _think_ the input is read @ 400Hz (same as physics rate), but not 100% sure on that. A bit of messing with an InternalsPlugin would confirm it, I'll have a go when I have time (if no-one else does it first).
     
  15. Spinelli

    Spinelli Banned

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    Hey TechAde ok now were talking. Ya in update 1150 rF1 added the Fixed Rate Inputs, I think the official quote from isi was "over 100hz" but dont quote me on that.

    So in rF2, im assuming the control input frequency is the same as rF1 BEFORE the 1150 patch, and therefore DOES NOT run on its own thread??...

    If thats the case then rather than shooting for minimum 100fps like in rF1 to match the control input rate for optimal precision, would it technically be "the more fps the better up until 400" with rF2? (Not that I am going to be shooting for 400fps by the way lol)



    On a side note, do I have the whole "Fixed Rate Inputs" plr option from rF1 completely backwards. Was it introduced so that REGARDLESS of how low your frames go, even if it looks choppy on screen at for example 15fps, the controls themselves will ALWAYS be at (or over) 100hz due to the control input rate running in its own thread?

    I would have thought this was what it was for, so that your control inputs would be refreshed at 100hz even if you are only getting 20 fps or 70, or whatever, but on the other hand according to peoples experiences in that link I provided, and mine aswell I could have sworn everything felt more direct and precise at 100fps rather than 50 or 60ish. (by the way I know my monitor does not refresh more than 60hz so I therefore shouldnt be able to tell a difference visually between 60 fps and anything over, but I am not talking about visual fluidity, I am talking strictly regarding your inputs from controller to game)
     
    Last edited by a moderator: Jul 18, 2012
  16. MaXyM

    MaXyM Registered

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    As far as I remember, input frequency as well as physics is independent from gfx refresh rate.
    It was stated on this forum at least once by some one from ISI team.

    Theoretically - yes. In reality, such low fps means whole system overloaded, which affects also peripherals.

    Because there is delay between physics calculation and what you can see on monitor. Less fps, one frame appear for longer time on the screen = higher delay. Lower fps also may mean what I wrote above: cpu/system overload

    BTW: in rF2 input frequency is greater than 100Hz because one steering wheel producer has been asked for improving steering wheel drivers (to improve the frequency from 100Hz to some higher one).
     
  17. deak1944

    deak1944 Guest

    "Synchronize Frame="1.00000" // Extrapolate graphics using estimated render time in attempt to more accurately synchronize physics with graphics, 0.0 (off) - 1.0 (full)" in the player file. Have you tested this?
     
  18. TechAde

    TechAde Registered

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    If you're talking about Thrustmaster and the T500RS that's not quite correct, the problem was with the FFB update frequency, not the controller input frequency. Thrustmaster released new drivers which cured that (CPU usage would hit the roof when rF2 threw FFB updates out to the wheel at 400Hz - so yes, FFB output rate of rF2 is matched to the core physics rate of 400Hz).

    I hear a rumour that Thrustmaster are working on firmware to increase the update rate to 500Hz to match the Logitech wheels, which I assume will encompass both position reporting and FFB rate.
     
  19. Marek Lesniak

    Marek Lesniak Car Team Staff Member

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    I've heard that too. Hope it won't take them much time to do that.
     
  20. Jos

    Jos Registered

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    @zeospantera

    i hardly see a difference, and complaining about lag with a wireless mouse is kinda funny...

    and what is a giant CRT? 24"? which is about the same as a 22" lcd...
     

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