Go Back   nV News Forums > Linux Support Forums > NVIDIA Linux

Newegg Daily Deals

Reply
 
Thread Tools
Old 06-06-03, 05:41 PM   #1
phil d
Registered User
 
Join Date: Jun 2003
Posts: 6
Default Help! : no polygon antialiasing

Hi, can anyone help me out here?

Ive just installed a geforce4 MX440 8xAGP with latest (4363) drivers on my redhat 7.2 system. But, when using openGL...

glEnable(GL_POLYGON_SMOOTH); totally fails to enable polygon antialiasing.

However, glEnable(GL_LINE_SMOOTH); works perfectly well, so there is no problem with antialiasing per se.

If anyone has any ideas how to fix this, I'd be extremely grateful!

Cheers,

Phil

ps XFree86 log attached.
Attached Files
File Type: log xfree86.0.log (18.7 KB, 99 views)
phil d is offline   Reply With Quote
Old 06-06-03, 09:25 PM   #2
bwkaz
Registered User
 
Join Date: Sep 2002
Posts: 2,262
Default

export __GL_FSAA_MODE=X
./yourprogramname


Replace X with a number. The possible values for this variable, plus the effect of each value on different cards, is all listed in the README.

This does sound kind of broken, but it may be that without that variable set, the GL libraries simply won't antialias polygons. Maybe. Though the variable controls full-screen AA, not just plain AA, so maybe not.
__________________
Registered Linux User #219692
bwkaz is offline   Reply With Quote
Old 06-07-03, 12:03 PM   #3
ssross
Registered User
 
Join Date: Dec 2002
Posts: 9
Default

I wrote a simple test and it seems to work on my setup (1.0-4363, RH8.0, Ti 4600)

Things to remember when using GL_POLYGON_SMOOTH:

- disable depth buffer
- initialize alpha channel in the frame buffer
- enable blend mode
- draw polygons front to back.

enjoy
scott
ssross is offline   Reply With Quote
Old 06-07-03, 12:05 PM   #4
ssross
Registered User
 
Join Date: Dec 2002
Posts: 9
Default

Lost the attachment somehow :-)
Attached Files
File Type: txt polysmooth.txt (1.2 KB, 171 views)
ssross is offline   Reply With Quote
Old 06-09-03, 11:14 AM   #5
phil d
Registered User
 
Join Date: Jun 2003
Posts: 6
Default

thanks for your help!

i tried the test code, but still no polygon antialiasing.

one possibility is that since the mx440 is a budget card, some desirable features like polygon antialiasing are disabled....

id be interested to know if anyone with an 'mx' card can get GL_POLYGON_SMOOTH to work.

Cheers,

Phil
phil d is offline   Reply With Quote
Old 06-09-03, 12:35 PM   #6
shassard
Asus Geforce FX 5600
 
Join Date: May 2003
Location: Vancouver, Canada
Posts: 36
Default

Polygon anti-aliasing is only available on the Quadro line of cards.

I've played around with poly-AA and find that the lines just look really blurry. I tend to prefer nice FSAA over just poly-AA anyday ..
shassard is offline   Reply With Quote
Old 06-10-03, 11:53 AM   #7
phil d
Registered User
 
Join Date: Jun 2003
Posts: 6
Default

hi,

is it known for sure that Quadro cards are the only current nvidia cards that support GL_POLYGON_SMOOTH?

Scott who posted above reported that it worked on his Ti card, so...

Can anyone verify that GL_POLYGON_SMOOTH works for sure with Ti cards, being certain that FSAA is definitely turned off?

You see, I need a dual VGA card that supports GL_POLYGON_SMOOTH...and Quadro cards are pricey.

Cheers

Phil

by the way, GL_POLYGON_SMOOTH is supported on my ancient bargain-basement ATI rage128 card, so I'm pretty unimpressed by nvidia not supporting it in products that are much higher spec than this in all other regards. Im guessing nvidia disabled it as a marketing strategy.
phil d is offline   Reply With Quote
Old 06-10-03, 05:49 PM   #8
bwkaz
Registered User
 
Join Date: Sep 2002
Posts: 2,262
Default

FSAA is off:

Quote:
$ echo $__GL_FSAA_MODE

$
When I run the provided test program, I get the output that I've saved to a screenshot and attached. It's a PNG format file (JPEG is lossy, and AFAIK PNG isn't, and losing any image data here might be significant).

Polygon AA seems to be on. I'm running on a GF4 Ti4200.

I'm also not using dual display, though...
Attached Thumbnails
Click image for larger version

Name:	polysmooth.png
Views:	166
Size:	6.3 KB
ID:	2284  
__________________
Registered Linux User #219692
bwkaz is offline   Reply With Quote

Old 06-11-03, 08:08 AM   #9
phil d
Registered User
 
Join Date: Jun 2003
Posts: 6
Default

thanks for trying that out...

looking at the picture you attached, the antialiasing is surprisingly crude. in the region of that picture that i have attached its clear that pixel intensity calculations are not determined exactly by the proportion of each pixel that is covered by the yellow shape. if it were, we would see a lot more than just 3 colours being used and the edge would not appear jagged at all on a well calibrated monitor.

Do other nvidia card owners get similarly bad antialiasing?

I have tried various ATI cards and found they all implement precise antialiasing - even the cheap cards.

Thanks a lot

Phil
Attached Images
 
phil d is offline   Reply With Quote
Old 06-11-03, 10:48 AM   #10
kow
Registered User
 
Join Date: Apr 2003
Posts: 20
Default

I've noticed the same effect. In the past (always using Nvidia cards) I kept trying GL_POLYGON_SMOOTH and I thought I was implementing it wrong because the AA looked so crappy. I finally gave up and just went with the export variable for FSAA in hardware.

I always assumed that the openGL would be strictly software AA and not take advantage of whatever AA algorithms have been builtin to the hardware.

Can anyone discredit or support my assumption?
kow is offline   Reply With Quote
Old 06-11-03, 08:13 PM   #11
bwkaz
Registered User
 
Join Date: Sep 2002
Posts: 2,262
Default

Quote:
Originally posted by phil d
looking at the picture you attached, the antialiasing is surprisingly crude.
Yeah, no kidding. The left edge of the front triangle is what you're talking about, right? It does look fairly crappy.

Wish I knew why...

<looking back through the thread>

kow -- I don't have a clue whether the hardware of software should be implementing polygon AA, so I can neither confirm nor deny your suspicions. Just in case you're wondering.

<looking back further>

Draw them front to back, huh? That's odd -- I'd think that if the AA happened when the polygons got drawn, then the driver (or the hardware) would need to know what color was behind the polygon in question, not the colors in front of it. Hmm... of course, I don't pretend to understand a whole ton of OpenGL (about enough to draw lines in 3D ), so yeah.
__________________
Registered Linux User #219692
bwkaz is offline   Reply With Quote
Old 06-12-03, 02:54 AM   #12
ssross
Registered User
 
Join Date: Dec 2002
Posts: 9
Default

FYI,
I found a GF2MX card and it does not seem to support polygon smoothing.

bwkaz - front to back does seem strange. It works because of the alpha term in the GL_SRC_ALPHA_SATURATE blend function.

(f, f, f, 1); where f = min(As, 1-Ad)

This mode uses the alpha channel to accumulate the coverage value for each pixel. The other functions work in simple cases but fail where 2 or more smoothed edges overlap.

As for the poor visual performance of the test program, it might be bad because of some default value that needs tweeked. For example I did not set the smooth hint to GL_NICEST -- though setting it does not help.

enjoy
scott
ssross is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


Similar Threads
Thread Thread Starter Forum Replies Last Post
High resolution versus antialiasing JemyM NVIDIA GeForce 7, 8, And 9 Series 43 10-06-02 03:28 PM
Antialiasing bug in 31.00 drivers? Mark_fox NVIDIA Windows Graphics Drivers 7 08-26-02 02:48 PM
How do you get the 10% antialiasing and anisotropy increase with the 30.30 drivers? imtim83 NVIDIA Windows Graphics Drivers 12 08-25-02 10:01 AM

All times are GMT -5. The time now is 05:18 PM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1998 - 2014, nV News.