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Visualizzazione risultati da 1 a 7 di 7

Discussione: The most significant

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  1. #1
    Utente L'avatar di Quedex
    Registrato il

    The most significant

    functionality in the new crop of cards is the truly
    flexible fragment programming, as exposed with ARB_fragment_program. Moving
    from the "switches and dials" style of discrete functional graphics
    programming to generally flexible programming with indirection and high
    precision is what is going to enable the next major step in graphics engines.

    It is going to require fairly deep, non-backwards-compatible modifications to
    an engine to take real advantage of the new features, but working with
    ARB_fragment_program is really a lot of fun, so I have added a few little
    tweaks to the current codebase on the ARB2 path:

    High dynamic color ranges are supported internally, rather than with
    post-blending. This gives a few more bits of color precision in the final
    image, but it isn't something that you really notice.

    Per-pixel environment mapping, rather than per-vertex. This fixes a pet-peeve
    of mine, which is large panes of environment mapped glass that aren't
    tessellated enough, giving that awful warping-around-the-triangulation effect
    as you move past them.

    Light and view vectors normalized with math, rather than a cube map. On
    future hardware this will likely be a performance improvement due to the
    decrease in bandwidth, but current hardware has the computation and bandwidth
    balanced such that it is pretty much a wash. What it does (in conjunction
    with floating point math) give you is a perfectly smooth specular highlight,
    instead of the pixelish blob that we get on older generations of cards.

    There are some more things I am playing around with, that will probably remain
    in the engine as novelties, but not supported features:

    Per-pixel reflection vector calculations for specular, instead of an
    interpolated half-angle. The only remaining effect that has any visual
    dependency on the underlying geometry is the shape of the specular highlight.
    Ideally, you want the same final image for a surface regardless of if it is
    two giant triangles, or a mesh of 1024 triangles. This will not be true if
    any calculation done at a vertex involves anything other than linear math
    operations. The specular half-angle calculation involves normalizations, so
    the interpolation across triangles on a surface will be dependent on exactly
    where the vertexes are located. The most visible end result of this is that
    on large, flat, shiny surfaces where you expect a clean highlight circle
    moving across it, you wind up with a highlight that distorts into an L shape
    around the triangulation line.

    The extra instructions to implement this did have a noticeable performance
    hit, and I was a little surprised to see that the highlights not only
    stabilized in shape, but also sharpened up quite a bit, changing the scene
    more than I expected. This probably isn't a good tradeoff today for a gamer,
    but it is nice for any kind of high-fidelity rendering.

    Renormalization of surface normal map samples makes significant quality
    improvements in magnified textures, turning tight, blurred corners into shiny,
    smooth pockets, but it introduces a huge amount of aliasing on minimized
    textures. Blending between the cases is possible with fragment programs, but
    the performance overhead does start piling up, and it may require stashing
    some information in the normal map alpha channel that varies with mip level.
    Doing good filtering of a specularly lit normal map texture is a fairly
    interesting problem, with lots of subtle issues.

    Bump mapped ambient lighting will give much better looking outdoor and
    well-lit scenes. This only became possible with dependent texture reads, and
    it requires new designer and tool-chain support to implement well, so it isn't
    easy to test globally with the current Doom datasets, but isolated demos are

    The future is in floating point framebuffers. One of the most noticeable
    thing this will get you without fundamental algorithm changes is the ability
    to use a correct display gamma ramp without destroying the dark color
    precision. Unfortunately, using a floating point framebuffer on the current
    generation of cards is pretty difficult, because no blending operations are
    supported, and the primary thing we need to do is add light contributions
    together in the framebuffer. The workaround is to copy the part of the
    framebuffer you are going to reference to a texture, and have your fragment
    program explicitly add that texture, instead of having the separate blend unit
    do it. This is intrusive enough that I probably won't hack up the current
    codebase, instead playing around on a forked version.

    Floating point framebuffers and complex fragment shaders will also allow much
    better volumetric effects, like volumetric illumination of fogged areas with
    shadows and additive/subtractive eddy currents.

  2. #2
    Oh my iPod! L'avatar di er patata
    Registrato il
    Bari Downtown
    ho capito tutto.......

    ma che cazz0 sta scritto? di che si parla?

    A volte credo di essere fin troppo nerd. Naa, never too much.
    Vuoi personalizzare l'aspetto del forum di GamesRadar? Clicca qui!
    Consortium.ru 2004 3D Motion Demo, shocking graphics. (QuickTime 60MB)

    Vuoi guadagnare soldi velocemente? Clicca qui!

  3. #3
    Registrato il
    ehm mi fate un riassuntino?

  4. #4
    Utente L'avatar di Holly
    Registrato il
    io credo siano modalita grafiche ma nn ne sn sicuro

  5. #5
    Utente L'avatar di Diadora
    Registrato il
    Interessante (se ho capito la cosa giusta); ma in che schede verrą integrato?
    Con "Diadora" non intendo la marca di scarpe.
    Ovunque tu vada ricorda che la Katana di Diadora sarą sempre al servizio della giustizia.

  6. #6
    Polygon Window L'avatar di Stix
    Registrato il
    Inviato da Diadora
    Interessante (se ho capito la cosa giusta); ma in che schede verrą integrato?
    Chi e che cosa??
    Non ho voglia di legger tutto...

  7. #7
    Sex. Drug. Rock'n'roll. L'avatar di Elladan
    Registrato il
    This is intrusive enough that I probably won't hack up the current


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