A simple explanation of different Anti aliasing

Discussion in 'Beginners Zone' started by chris1515, Feb 7, 2022.

  1. chris1515

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  2. Davros

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    What no Quincunx anti aliasing

    Quincunx anti aliasing works by using 5 samples per pixel in the following configuration:

    B C
    *--------*
    | A
    | *
    |
    *--------*
    D E

    A is the center of the pixel that you would normally draw. It has a weight of 1/2.

    B,C,D,E are offset from the center by half a pixel and each having a weighting of 1/8.

    The weights of all the samples add up to 1.0 but the center has the heaviest contribution to the final image.

    In shadertoy, quincunx AA means that you have to do 5 times as much rendering per pixel, but
    in real rendering situations, you can achieve quincunx by doing two full screen renders.

    The first render renders the screen with an offset of half a pixel (-0.5,-0.5) and the second render
    uses the results of that first render to get the corner pixels to mix into the center pixel.

    The benefit of doing this is that those corner pixels can be shared by all the pixels that use them
    which makes it so you are basically doing 2x super sampling AA, but you get benefits closer to 5x!

    https://www.techpowerup.com/forums/threads/different-types-of-aa.149319/
     
    snc, digitalwanderer and chris1515 like this.
  3. digitalwanderer

    digitalwanderer Dangerously Mirthful
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    As I recall, Quincunx really sucked though visually. The original blur filter even.

    If I'm wrong please kick me, my memory isn't my strongest point and I think I remember GeForce2 MX400 had hardware support for it but it still sort of sucked.

    Very low performance hit though, I remember that.
     
  4. Davros

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    The only game i can remember that had an option for quincunx was Soldier of Fortune 2, but I dont have it installed to test it
     
  5. PSman1700

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    You could force enable it using the NV control panel, was quite good at the time with no performance cost (ti4200 and up).

    Geforce 4 Ti series i think. While not the best AA solution at the time, it had virtually no impact on performance either.

    Didnt OG xbox had something like this too?
     
  6. digitalwanderer

    digitalwanderer Dangerously Mirthful
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    GF4 MX400 then, it was a really cheap one.
     
  7. PSman1700

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    Hm, not sure if the GF4MX gpus had quincunx support, they where basically Geforce 2 gpus (rebranded). Geforce 3 and up had support for it, i think. Anyone remember the details?
     
  8. Davros

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    PSman1700 likes this.
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