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View Full Version : Is it okay to rely on glCopyTexImage2D() working with a hidden window?



halo
10-20-2006, 02:58 PM
The command glCopyTexImage2D() works fine on my GEForce 7800 when used with a hidden window. Although GLReadPixels() does not. Is it okay to rely on a hidden window working with glCopyTexImage2D()?

Bob
10-20-2006, 03:08 PM
No. The specification explicitely says that the content of any occluded part of the frame buffer, or any part outside the screen, is undefined. It may work, and it may not.

halo
10-20-2006, 03:26 PM
How about if the window is hidden, but set to be on top of other windows? Technically, it wouldn't be offscreen or occluded.

Korval
10-20-2006, 04:50 PM
How about if the window is hidden, but set to be on top of other windows? Technically, it wouldn't be offscreen or occluded.If you can't see the window, don't rely on it. Just use an FBO.

halo
10-20-2006, 05:22 PM
Okay, I'll suck it up and implement an fbo.

I found a straightforward example here:
http://www.beyond3d.com/forum/archive/index.php/t-25031.html

The spec for the fbo extension was freakin' 118 pages! :eek:

halo
10-20-2006, 06:55 PM
Oh my god, I coded FBO into my system, had to compile three times and fixed a little syntax error each time, and it just worked on the first compile!

halo
10-20-2006, 07:10 PM
Hmmm, it looks like FBOs don't do multisampling. My shadows are rather jagged looking. How can I soften them? It looks like RenderbufferStorageMultisampleEXT() isn't implemented yet, at least it isn't supported by my GEForce 7800.

Korval
10-20-2006, 07:52 PM
I'm not exactly sure what it is that's up with IHVs with regard to GL recently. But they don't seem to be tending to their OpenGL like they normally would. I mean, we have these extensions for multisampled buffers and scaled blitting, but nobody's bothered to actually implement them.

Maybe they're too busy with GL 3 implementations?

Zengar
10-21-2006, 06:48 AM
I was assured by a nvidia employee that the new extensions (multisample and blit) will be aviable in the next generation drivers on the current hardware.


... that was about 4 month ago ^^

zeoverlord
10-21-2006, 08:06 AM
Originally posted by Korval:
Maybe they're too busy with GL 3 implementations? Yea probably, that and SM4, my guess is that they have a whole bunch of extension implementations and new extensions lined up for nvidias g80 release driver (10x.xx maybe) and ATIs equivalent driver release.
This and preparing the drivers for the new object model and GL3 might make them take their sweet time.

Ysaneya
10-24-2006, 01:49 AM
They're currently putting all their efforts into Vista (was confirmed by NVidia's devrel), you'll probably have to wait until Vista is released so that the concentrate on GL a bit more.

Y.