Weird flickering after switching to an ATI GPU [Video]

Posted by Willb 
Hi all,

Just wondering if anyone can tell me what's going on here. Ever since i switched to a 4870 from an 8800 (I love the Nvidia drivers compared to ATI's poor excuse of a video driver..) I get this weird flickering/shimmering of distant objects in Grand Prix 4. I've tried forcing AA/AF in the GPU drivers, and it doesn't seem to make any difference. It's not the track as it does it on all the tracks I tried, and its only since I've been running on a 4870.

What am I missing here!?





Any help would be great,
Thanks
Wills

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Check the draw distance, and I've not looked at the vid.


[www.mediafire.com] Some say you should click it, you know you want to. :-) [www.gp4central.com] <----GP4 Central
Hi Mortal,

Thanks for the suggestion, however its not that as i can minimize the effect with 24x AA sampling, but its still there and annoying ust not as horrendous as it is with game controlled aa :(. Please don't tell me all you ATI users just put up with this in GP4 :(

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It looks like some low precision Z-buffer and that's quite weird for such high end graphical card. (So if you have any DirectX Z-buffer setting in the catalyst panels, the best solution might be to increase it to 24 or 32 bits)

You can try the following tip but I'm not sure it will fix this anyway:
set first line of your graphics.cfg file to 1 and seek for this line
; Set 0 => no 8bit alpha (all stencil - yuck) 8 => all 8bit alpha (no stencil - nice) else 1-7 as cut off
If value in before ";" if 8, set it to 7, save changes and try ingame without any change in the game options

PS : I just found interesting details about catalyst settings here, just try to avoid Z compression and other z buffer tweaks for GP4.





Edited 3 time(s). Last edit at 05/08/2010 11:19AM by Lo2k.
It's a little bit difficult to see the problem in that video, but I suspect I have exactly the same problem and am using an NVidia GTX260. The crowd flickers like mad. So this is not necessarily an ATI issue. I thought everybody had this problem - thought it was just a GP4 thing so didn't think anything could be done about it!

Well, nothing is ought to flicker in GP4 but a very few surfaces (mostly with new tracks) that were set too close each others by track creator. So it should really concern 2-3 faces and nothing more.
I had 2 or 3 different (Nvidia) graphic cards and I never got so many flickering objects than in the video above.
So this is not quite a game issue, more a Z-buffer one imho.

PS: Looking for info again, I found this Rivatuner (nvidia only) option:
The LMA tab provides access to the 'Enable lossless Z-buffer compression' option, which should be ticked for maximum performance. The Z-Buffer controls the rendering of depth in 3D games, such as which objects are hidden behind others when viewed at a distance. Z-buffer compression makes this process much more efficient, and this option should only be unticked for troubleshooting purposes if you notice issues with objects showing through each other or other distance-based graphical glitches. The 'Enable early Z-occlusion culling' option is similarly strongly recommended as being left ticked. Only untick for troubleshooting purposes, as unticking it will reduce performance.

Just reading at this option reminds me this one from graphics.cfg file :
0 ; Crude quadtree cull only (0=> off, 1=>always, 2=>only for TNL); recommended for fast gfx, low cpu
You might try to play with 0-1-2 values and see if it help in any way





Edited 2 time(s). Last edit at 05/08/2010 11:28AM by Lo2k.
Thanks for all the suggestions Lo2k, Ill give them a go.

Mr Pibb, make sure your watching the 720p version on youtube, and notice particually at Club exit flickering white wall and catch fence, and also hanger straight flickering grandstands at the end and really noticible after Priory on the woodcote grandstands and finally on the Start finnish bridge. It's almost as if the card cant decide what is infront of which object, very odd.

Ill get to work playing with your suggestions Lo2k, but i know for a fact that my stencil setting is already on 7.
Thanks,
Kind Regards,
Wills

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Doh! Justed watched the 720p. Yup, that's EXACTLY the same problem I have and I'm using Nvidia 260GTX.

I changed my stencil setting from 7 (which is what it was already on) to 8 and the flickering crowds have stopped, but instead of flickering crowds I now have half full granstands in some places, full in other places. Crowd animation is still present where the crowds are missing. But at least they're not flickering! Walls etc still flicker if they did before, though it doesn't seem as bad. Hard to say 'cos most of the time I don't take any notice - I'm too busy driving to see the scenery but the flicking does distract me...

Hehe maybe I can be much faster if the flickering goes away ;)

Well I just tried fiddeling with some settings and non of your suggestions help unfortunately Lo2k. The stencil setting at 8 makes half the objects invisible and wierd, the crude cull option made no odds.

I played in ATI Tray Tool and disabled all the zbuffer quick clear and other optimisations i could find but it doesn't solve the problem :(. Really annoying as I never once had a single issue with any of my Nvidia cards. Im about to try creating a fresh f1graphics.cfg file, but I doubt that will help :(

So Annoying especially when im trying to test for bugs and stuff in the circuit :(.

Edit: Fresh F1 Graphics.cfg didn't make any odds either. Lame :(

More proof that ATI fail at writing drivers for their hardware. :(

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Edited 1 time(s). Last edit at 05/08/2010 02:56PM by Willb.
Did anyone ever get a fix for this? I'm having exactly the same issue as this. I found the video from the first post on you tube: [www.youtube.com]

I have an GTX 1660 super as my graphics card.

As mentionned before, it's either HW or drivers related. Make sure that you have disabled all optimization regarding Zbuffer depth.

As Lo2k mentionned you can try to change the quadtree culldown value and see if it changes something. Don't bother changing the stencil value to 8, you'll probably get more side effects than problems solved. (for me it leads to transparent texture parts becoming black).

On a totally different topic: does anybody knows which wheel this screenshot features ? It looks really nice !
that's the generic steering wheel from the mod 2002, if i'm correct



Edited 1 time(s). Last edit at 07/20/2021 09:44AM by quickslick.
I didn't really understand the bits about the Zbuffer. Where do I disable/change that? I couldn't find it in the normal Nvidia control panel. All my drivers are up to date, and the 1660 Super is a pretty recent card.

I've had the stencil value at 8 before and it took me months to realise that was what was causing the sky to keep falling down after 5 laps! So I'm not setting it to that again. Going lower doesn't really help the flickering.
@quickslick: indeed, thanks. I

You should keep the stencil buffer to 7.

The Zbuffer is a buffer in which the distance to the camera is stored for each pixel. The depth in bits controls how accurate the value is. Lower buffer depth gives less values (more approximation), so i can produce flickering if two objects are very close to one another. The value to be forced in the drivers for performance reasons. 20 years ago it could make a difference, today it does not.
I don't know Nvidia drivers, i've been using amd cards for more than 10 years now, but maybe if you have profiles to control games, make sure you don't have any option limiting the zbuffer depth.

Have you tried renaming f1graphics.cfg to start with a clean one ?
I didn't find anything to do with buffer in the Nvidia control panel, but I found some hidden options in dgVoodoo which said buffer and I changed them to 32 bit. That seemed to do the trick! There is a slight flicker with the crowds in the grandstand still, but nothing like what it was. The buildings and trackside objects don't look like they're constantly redrawing themselves any more. So that's a win as far as I'm concerned!

Good to hear and thanks to share it.



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