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Is antialiasing supposed to work?

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  • Is antialiasing supposed to work?

    I was trying the aapoly.c demo from the Red Book for OpenGL 1.1.
    What I see is most certainly not antialiased; there's no change when t is pressed.

    Never having tried it before, has antialiasing ever worked in the FOSS ati drivers?

  • #2
    The code for reference:

    On hardware DRI:

    On Mesa software renderer:

    This is on X1300 Pro, Mesa 7.4.4. Anyone know something about this?
    Is this a known missing feature, or should I file a bug?
    Last edited by curaga; 12-31-2009, 09:26 AM.


    • #3
      I didn't think AA had been implemented yet. Getting the applications to render properly seems to be higher priority than making them soft and fuzzy


      • #4
        Well, considering this is OpenGL 1.1 functionality , and Mesa 7.4.4 advertises 1.3, I thought it should work.


        • #5
          Remember that Mesa is *not* OpenGL, does not use the OpenGL name, and is not certified against OpenGL standards.

          Mesa implements an API "very similar to OpenGL" and exposes GL levels and extensions as guidelines to apps in order to provide the best results. The devs had the option of holding back higher GL levels and extensions until every corner case was implemented and confirmed to be working correctly, but that would have only made the user experience a *lot* worse with no obvious benefit.

          I have updated the RadeonFeature wiki page to add a row for anti-aliasing. I left everything as UNKNOWN for now - AA might have been enabled on older chips, not sure.

          Not sure if it's worth filing a bug on this - if one of the devs comes back and says "yes" then go ahead, but otherwise the wiki page should be enough to track the status.
          Last edited by bridgman; 12-31-2009, 10:48 AM.


          • #6

            I do disagree that AA is a corner case, many people would use it if it only were available


            • #7
              Agreed; I wasn't actually referring to AA as a corner case but the logic is the same whether we are talking about a feature like AA or something that apps rarely use (eg the noise functions in GLSL). Either GL levels are advertised to provide the best user experience, or they are advertised on the basis of strict compliance.

              The devs are going with "best user experience", which seems right to me.


              • #8
                GL1.1 polygon AA is a rarely used feature known not to work in all circumstances, it's deprecated in OpenGL 3.0 and removed in OpenGL 3.1. Modern AA used in games is often referred to as multisampling or MSAA and it's part of OpenGL 1.4, but the GL specification does not necessarily require the number of samples to be greater than 1, meaning that MSAA is not mandatory.

                Of course, getting things to work first and then speeding them up has higher priority than eye-candy.


                • #9

                  Originally posted by bridgman View Post
                  I have updated the RadeonFeature wiki page to add a row for anti-aliasing. I left everything as UNKNOWN for now - AA might have been enabled on older chips, not sure.
                  What is "alising", and why are you against it ?


                  • #10
                    It's... um... kind of like aliasing...

                    Fixed, thanks.


                    • #11
                      Looks like the sharp borders aren't the only problem with that demo... I mean, the sample picture shows transparency whereas the hardware one only seems to cope the outermost surface.