Screen "tearing" in OpenGL?

[Andre]

Hi,

Can anybody help me how to elimimate screen "tearing" in OpenGL games (Quake II, Half-Life etc.)? It shows itself as, e.g., jagged ("stepped") edges when you quickly turn around, or as flickering horizontal lines when firing weapons.

I remember on my old Voodoo card I could set some parameter for Glide which would increase the frame rate with similar "tearing" effect, but I've always kept it off since I prefer good image quality to shear speed (I cannot remeber the parameter, though). Is something similar can be done in OpenGL (or Direct3D for that matter)?

My system:
G400 DH 32Mb on GB GA-6BE MB
(had to force AGPx1 to eliminate crashes)
PIII 450 with 64Mb
Win98, Directx7, TurboGL

Andre

[Wombat]

Sounds like your v-sync is disabled.

[Alec]

Yep.

------------------
Intel Celeron 433, G200 8Mb AGP, Intel Atlanta 440LX, Soundblaster PCI 128, 96 Megs SDram, 4.3 WD Caviar HD, AOC 5VLR monitor 15".

Remember folks:
"Computers are useless. They can only give you answers"
Pablo Picasso

[Andre]

Thanks, guys.

To enable Vsync, is it sufficient to add the string FlipOnVblank (set to "1") to ...\DirectX in Registry? (I tried this - did not seem to change much)

[Alec]

What, even with vsync activated the tearing goes on? That´s strange...
What is your refresh rate?
Vsync means that the frame rate is controlled to never overcome the refresh rate value. The graphics card waits for an image to be redrawn by the monitor before drawing itself one.
So, if you have a 75Hz refresh rate in DirectX (you can force it in DXDIAG) and Vsync activated, your games never go over the 75fps threshold, but the tearing is over.
Vsync is an option in Powerdesk, also.

OOOps, I forgot you were talking about OpenGl... sorry! I´m not sure about OpenGl vsync.

------------------
Intel Celeron 433, G200 8Mb AGP, Intel Atlanta 440LX, Soundblaster PCI 128, 96 Megs SDram, 4.3 WD Caviar HD, AOC 5VLR monitor 15".

Remember folks:
"Computers are useless. They can only give you answers"
Pablo Picasso


[This message has been edited by Alec (edited 18 November 1999).]

[Wombat]

Andre,
Editing that entry may have helped DirectX games, but that's not OpenGL. You might be able to do it in the Display Properties for the Matrox card., or some command in the game. I think that v-sync is actually on one of the menus in QuakeII - poke around.