View Full Version : hardware AA lines on NV28?
10-01-2003, 12:59 AM
I have read some stuff saying that hardware antialiased lines are enabled by default on the NV28 chips, although they are slower than on the Quadros. Does anyone know something sure on this topic? I'm interested if hardware AA line and triagle strips would be also available on the NV3x. As far as I know (from testing on various cards), the AA stuff is not only 3 times slower, but has rendering artifacts (missing pixels).
10-01-2003, 04:33 PM
I don't know about the NV28, but if you want AA Lines and Tris you have to mod your NV30 via Hardwaremod. It is very risky, because the NV30 Chip has some SMD stuff under the BGA package. You would have to change the position of the R1 Resistor of the NV30, but this could kill all the SMD under it. Until now i killed 2 cards. I don't know how to solder this part. All other NV Cards did not do any Problems (i did not try the NV25+ Family).
So if you need AA lines at low-cost, buy a Radeon.
10-02-2003, 01:31 AM
Thanks for the information.
I already have tried smooth AA line and triangle strips on a Radeon 9700, and they don't work as on a Quadro; the lines are relatively smooth antialiased, buth have missing pixels where the slope changes between quadrants (same as on GeForce2 cards); and for the triangle strips, the AA just didn't work.
I'm not talking about hardware modding, or even driver hacking: my App needs the AA stuff (it's doing kind of Postscript display) and in some countries it's hard to find a Quadro or FireGL.
I read in the Unwinder articles on Softquadro4 that on revision 3 of the NV25 the AA lines worked by default, just 3 times slower than on a NV25GL. I hoped that would mean later products, like the NV28 or NV3x, would also have it by default, only slower than their Quadro brothers; I think it would be nice to have these features on mainstream cards, there are other features that could remain exclusively on professional cards; I'd like to buy a GeForceFX 5900 and play games on it, but also to have AA lines for professional usage, at the acceptable speed level of a QuadroFX 500.
10-03-2003, 11:05 AM
RivaTuner support both SoftQuadro(for det40 maximum) & SoftFireGL(for catalyst 3.7) and give fully hardware support fot AAlines.
10-03-2003, 12:32 PM
Originally posted by Tzupy:
the lines are relatively smooth antialiased, buth have missing pixels where the slope changes between quadrants (same as on GeForce2 cards)
If you mean that you'd like line strips to be fully joined, it's not possible with the current GL specification. Filling the gaps is not specified. It will be implicitly fulfilled with line width <= 1, but not for wider lines.
10-04-2003, 04:49 AM
Thank you for the answers.
I'm using Softquadro on GeForce2Ti, with good results, and am aware that SoftFireGL is also available, but I can't ask inexperienced customers to do that; some of them would just say 'it's not working'...
On Quadro the line strips are perfectly joined, so maybe just the generic MS implementation of OpenGL can't join the lines properly (it has to do with the way they are drawn).
10-04-2003, 09:00 AM
I remembered something: if I requested the DRAW_TO_BITMAP for the rendering context, then I was getting software rendering (really slow, so it must be software only), and the antialiased line strips were properly drawn, no missing pixels. Anyone can explain that?
10-04-2003, 12:46 PM
It sounds to me as if the software implementation is written to fully fill the gaps. That seems reasonable -- you're already in software; don't worry about an additional very small speed hit (comparably small, that is :-)
It also sounds to me as if you're designing a program that needs FireGL/Quadro cards. Thus, you have to tell your customers that this is what they need. I also think the 3DLabs/Creative cards (Wildcats, etc) will do the right thing here.
If some customers (or you) want to try to save a little money by modding/tuning a consumer card, then that's fine, but that doesn't sound like something I'd build a business around.
10-07-2003, 10:51 PM
You may also try alternate AA techniques... It sounds to me as if you are not really looking for real time rendering (?), so you may be able to do the old tiled rendering trick with filtering and downsampling (in software). You can also use FSAA, which should be supported on most modern cards.
10-16-2003, 09:53 AM
I use AA lines in my NV25, and i not get serious penalty in perfomance, but this options not good - if i render first nearest line, and draw far line with intersection in screen view, i have some pixels wrong. This is correct, AA work with alfa-channel.
Best is use multisample for full scene, if this very needed (antialiasing).
And in TNT2 this mode work with great speed down. (10x or greater).
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