PDA

View Full Version : GL_SGIX_generate_mipmaps



davepermen
04-20-2002, 12:37 AM
well then, dave once again..

i'm just playing around on blurring images, and, as the way with the multiple smaller images and drawing recursively the previous tex on the smaller only worked on my gpu and one other, i gave it up (difficult to find the bug then.. http://www.opengl.org/discussion_boards/ubb/smile.gif)
so i looked for some new ways, means using the mipmap-layers of the texture. now as first try i thought, to find out if i get GL_EXT_texture_lod_bias working correctly, u use GL_SGIX_generate_mipmaps to do the job for me.. and well, it works, i can directly choose and draw one layer of the mipmap..

just one problem: the mipmaps are crap. why? cause they are generated as crap. namely with nearest filtering they generate the downsamples..

the result (drawn with nearest filtering to see it bether) looks like this: http://tyrannen.starcraft3d.net/nearestfilteringofGL_SGIX_generate_mipmapsongeforc e2mx.jpg
and as you can see, it gets all "shifted down", means on the right, the blue triangle gets much bigger in the lower lods, and the orange one gets smaller and smaller..

thats not useful for blurring the screen. (the blue triangle gets much bigger blurred than the orange one, but they are of the same size..)

how can i get other filtering-methods with generate_mipmaps? or do i have to do it myself? thats no problem, i can do that (and hope it runs on other hardware as well this time http://www.opengl.org/discussion_boards/ubb/wink.gif)

R-C
04-20-2002, 02:45 AM
Quick check : GL_GENERATE_MIPMAP_HINT_SGIS is set to GL_NICEST?

Rich


[This message has been edited by R-C (edited 04-20-2002).]

davepermen
04-20-2002, 09:15 AM
don't see a difference (yet) i'll play around with it.. any statements from nvidia-guys how the mipmaps are generated for render_texture's on geforce2? and, if the hint helps at all?

mcraighead
04-20-2002, 11:09 AM
This is a bug I fixed a while back. If you get recent enough 28.xx drivers they should include the fix.

- Matt

davepermen
04-20-2002, 11:25 AM
i have the newest from nvidia.com... well.. i'll download them again and installem http://www.opengl.org/discussion_boards/ubb/wink.gif

mcraighead
04-20-2002, 12:07 PM
May not be on our web site, not sure.

- Matt

davepermen
04-20-2002, 12:54 PM
well.. its 28.32_winxp.exe
new enough?

mcraighead
04-20-2002, 04:31 PM
I doubt that'll have the fix.

- Matt

davepermen
04-21-2002, 12:23 AM
now using 28.80. no difference.. and i set the hint in every renderingcontext (dunno if this is needed, but for making sure its not me http://www.opengl.org/discussion_boards/ubb/wink.gif)

not to use like that.. annoying..
think i'll stick back to the old version, there the driver bug was not on my gpu but on everyone's else (so at least i can see the blur correctly http://www.opengl.org/discussion_boards/ubb/wink.gif)