View Full Version : minimum pbuffer resolution ?!

12-03-2003, 06:08 AM

I'm wondering if there's a minimum value for the viewport when you render to pbuffer ??!!

cause when I'm downsizing my shadow map to 16x16 pixels (or less), I get a crash after a few seconds. although the shadow map is well rendered !

Have you ever seen something like that ?!
Give me your opinion !


12-03-2003, 06:51 AM
one more detail :

It seems that the problem comes from the wglMakeCurrent() call, with pbuffer context arguments. Cause when I remove it, there's no crash anymore (and no shadow map also).

Does it sound clear now ?!
any idea ?!!

thank you

12-05-2003, 06:54 AM
hi again,

just a little hint :
I'm using directly render-to-texture method with my pbuffers !

hope It may help you to help me !
thanks anyway
I still trust there will be an answer

12-08-2003, 12:50 PM
a hint about your hardware/drivers would be also very usefull..
btw. isn't it senseless to use pbuffers smaller than 16x16 ???
i mean, you are sending more overhead to the driver than the actuall pbuffer has in bytes (16X16 rgba == 1024 bytes!!! i think, the driver overhead used to manage even smaller pbuffers will consume more memory then the actual pbuffers...)

isn't it much better to allocate one big pbuffer and to use it for more than only a single texture ?

12-08-2003, 10:53 PM
hi adrain,

Here are my hardware settings :
I've got a geforce4 ti 4600
IRQ :16, Bios :
BUS :AGP 4X , Memory 128Mo

I do agree with you : 16x16 shadow mapping does not have any sense. But I worry about every bug I meet. This bug could hide a much bigger and important problem. So I'd like to resolve it , to make my application stronger, better , faster !

I've my hardware give you any idea, please tell me !


12-08-2003, 11:45 PM
Is your app working with 256x256 pbuff?

12-09-2003, 12:04 AM
yep it works very well with a 256x256 resolution ! and also with 128x128 and above till 32x32, but not with 16x16 and under.

16x16 weems to be some kind of limit
The application is only running a few seconds with this resolution.

12-09-2003, 12:58 AM
Could be driver bug then... Try to check your app on different setup, drv rev. There is nothing about min pbuffer size in specs http://www.opengl.org/discussion_boards/ubb/frown.gif For now try to stick with 128x128 buff, shouldn't be that much of a penalty.

12-09-2003, 03:00 AM
is there a better driver for geforce 4 ti 4600 ?
I am obsolete ?! where to find a new one ? on nvidia web site ?!

thank you