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Zorro0033
10-11-2002, 04:20 AM
Any one else having problems with rendering large textures (ex 1024*1024)?

When I do this the scene rotates very jumpy, just like opengl has to much to handle. If I have meny small textures (ex 256*256), every thing works fine!

SirKnight
10-11-2002, 07:16 AM
Maybe your out of texture memory. That would explain the slow texture performance. A texture that is 1024x1024x32 takes up 33,554,432 bits. That's a little more than 30MB which is a pretty big chunk of texture memory. Whereas a texture of 256x256x32 is only 2,097,152 bits; Close to 2MB.

-SirKnight

SirKnight
10-11-2002, 07:18 AM
BTW, the 32 means 32bit color precision, not to be confused with the 3rd dimension of a 3d texture. http://www.opengl.org/discussion_boards/ubb/wink.gif

-SirKnight

Lev
10-11-2002, 07:30 AM
Sirknight:

bit bytes bits bytes?

1024 x 1024 x 32 bits ==
1024 x 1024 x 4 bytes = 4 MB

-Lev

SirKnight
10-11-2002, 09:02 AM
SON OF A!!! You're right. I can't beleive I did that. Sorry about that mistake, gosh I feel like a complete moron now. http://www.opengl.org/discussion_boards/ubb/biggrin.gif

I thought something sounded not quite right. http://www.opengl.org/discussion_boards/ubb/smile.gif I said bits and looked at it like it was in bytes and everything went down hill from there. Bleh.

-SirKnight

[This message has been edited by SirKnight (edited 10-11-2002).]

SirKnight
10-11-2002, 09:09 AM
Well anyway, reguardless if I got the numbers wrong or not http://www.opengl.org/discussion_boards/ubb/wink.gif it still shows that the larger texture, obviously, takes up more space. So if you don't have your textures managed in a good way or out of memory or something, then texture thrashing will go on and since that larger texture takes up so much more memory, the effect of the thrashing will be quite great.

-SirKnight

heath
10-11-2002, 06:23 PM
Dont' forget that if its mipmapped, that an additional ~30%. I quick test you might try (If running under windows) would be to switch your desktop to 16bit, and see if your performance improves. Most Cards, unless told otherwise use the desktop color depth for textures.

Hope this helps,

Heath.

zed
10-12-2002, 07:39 PM
in adition to what the previous poster said u will most likely see a performance increase when u use mipmapping, so enable it (if u havent already)