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r200 register to enable SSAA

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  • r200 register to enable SSAA

    Hi!
    As ATI delays publishing register reference documents continuously, I have lost hope to figure out how to enable FSAA (or call it SSAA, whichever you like)

    To prevent confusion I'd like to emphasize that I don't mean xorg.conf setting to enable FSAA. I look for the method to enable FSAA in driver level. Any Ideas?

    Regards,

  • #2
    You are talking about Super-Sampling Anti-Aliasing/Full-Screen Anti-Aliasing, right?

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    • #3
      Exactly that's what I am looking for desperately...

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      • #4
        It's not covered by the doc we were planning to re-release either. AFAIK there's a lot more to SSAA than just setting a register bit, but we can check.

        EDIT - Alex took a look through the internal hardware design info and didn't see anything that looked SSAA-related there either. That implies the SSAA was being done using the 3D engine, originally in the driver but presumably it makes more sense to do it in the compositor these days.

        EDIT 2 - from skimming the old programming guide, it looks like the R200 used MSAA rather than SSAA for full-screen AA. That might be why we didn't find anything.
        Last edited by bridgman; 03-26-2009, 02:26 PM.

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        • #5
          So super-sampling is basically a matter of rasterize->downsample, then?

          Is this similar on newer hardware, as well?
          Last edited by TechMage89; 03-26-2009, 11:09 AM.

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          • #6
            Bridgman, the capability is definitely implemented in the Catalyst driver. As it is not open source, perhaps you may want to delve into its source codes regarding the details.

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            • #7
              Originally posted by wildcard View Post
              Hi!
              As ATI delays publishing register reference documents continuously,
              Something I should mention; we have *not* delayed publishing register reference documents at all. We identified the *sequence* of tasks we would be working on, and we're getting fairly close to the point where we will be looking at older GPUs. In the meantime I said that *if* we were able to find an editable copy of the existing docs we would try to re-release them sooner. That's it.

              We may not have published specs as quickly as you *hoped*, but that's different.

              Originally posted by kurukafa View Post
              Bridgman, the capability is definitely implemented in the Catalyst driver. As it is not open source, perhaps you may want to delve into its source codes regarding the details.
              We will do that when we start working on the older GPUs. Right now our focus is still primarily on 5xx and newer parts, at least until we see basic 3D for 6xx/7xx and some basic power management in the open source drivers.
              Last edited by bridgman; 03-26-2009, 02:27 PM.

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              • #8
                Something I should mention; we have *not* delayed publishing register reference documents at all.
                I don't mean any offense, apologies. I respect your work.

                So super-sampling is basically a matter of rasterize->downsample, then?
                Well it appears there is something more than that. I've already tried downsampling rasterized image, but it does not perform as does catalyst.

                from skimming the old programming guide, it looks like the R200 used MSAA rather than SSAA for full-screen AA. That might be why we didn't find anything.
                Then, what is your suggestion for me to proceed? Shall I expect recieving any further details any soon?
                Any sort of clue is very appreciated. I'm in such a trouble you cannot imagine

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                • #9
                  As far as I remember you really need a memory manager.

                  you just need to render to a backbuffer 2xwidth + 2xheight, and downscaling on the blit to the frontbuffer or using the 3D engine to scaledown with smoe filtering. or maybes thats super-sampling, I forget the details

                  I don't think there is much in a register.

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                  • #10
                    IIRC, the R200 only did SSAA, but with a programmable or pseudorandom sample pattern with from 2 and 5 samples per pixel (as opposed to a simple 2x2 grid, which as airlied points out doesn't really require any special hardware functionality at all--that's what the R100 had, BTW)

                    I remember that it took several (Windows) driver revisions for ATI to get the R200's FSAA to actually work, so perhaps it was mostly driver magic all along, somehow using the 3D engine to implement the variable sample patterns? Either that or the hardware that set up the sample patterns was buggy somehow.

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