Fog formats

Discussion in 'Architecture and Products' started by Secessionist, Sep 27, 2010.

  1. Secessionist

    Banned

    Joined:
    Feb 10, 2010
    Messages:
    71
    Likes Received:
    0
    What fog formats are in current hardware? Which ones are missing from, say, the Voodoo5 or the GeForce FX?
     
  2. Davros

    Legend

    Joined:
    Jun 7, 2004
    Messages:
    17,502
    Likes Received:
    4,905
    I'd say none, obviously cards can do all kinds of fog but there are no dedicated units
    a better question would be what fog formats are supported in current api's/drivers
    and I would say all of them that were there in the past are still there now (*but then again ;))

    Range or Radial fog
    Eye-Plane fog
    table fog * this may have been dropped from current drivers remember the enable fog table emulation option in nv drivers
    vertex fog

    edit: the enable table fog emulation was a compatibility settings as some cards/games didnt do it right

    ps: found a good explanation of fog table emulation :
    Fog Table Emulation: This is for 3D chips that don't support looking up the fog level by distance from the camera per pixel. Instead it emulates it by looking up the fog level at each vertex in the table and interpolating it
     
  3. sebbbi

    Veteran

    Joined:
    Nov 14, 2007
    Messages:
    2,924
    Likes Received:
    5,296
    Location:
    Helsinki, Finland
    Then there was of course linear and exponential fog falloff. If I remember correctly, the range fog was vertex based, and table fog was pixel based. Table fog supported exponential falloff (I remember using it in my first graphics engine).

    New shader based hardware can emulate all these fog modes by a few extra pixel shader instructions. Fixed function hardware fog support hasn't existed for a long time. It died at the same time fixed function T&L died. Both T&L and fog are emulated by shaders if you run and old DX version (or fixed function OpenGL) on the new cards.
     
  4. Secessionist

    Banned

    Joined:
    Feb 10, 2010
    Messages:
    71
    Likes Received:
    0
    Okay thanks. That's actually good to know.
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...