“EXACT: algorithm and hardware architecture for an improved A-buffer” by Schilling and Straßer

  • ©Andreas Schilling and Wolfgang Straßer




    EXACT: algorithm and hardware architecture for an improved A-buffer



    The EXACT (EXact Area Coverage calculaTion) algorithm presented in this paper solves the Hidden Surface
    Elimination (HSE) problem on the subpixel level.
    The use of subpixel masks for anti-aliasing causes some
    problems with the HSE on the pixel level that are difficult to overcome. The approximations of the well
    known A-buffer algorithm are replaced by an exact solution that avoids erratic pixels along intersecting or
    touching surfaces.
    With EXACT the HSE problem on the subpixel level
    is solved with the help of p-masks. P-masks (priority masks) are subpixel masks that indicate for each
    subpixel which one of two given planes is closer to
    the viewer. An algorithm to produce the p-masks in
    an efficient way and its hardware implementation are
    presented. The p-mask generator is used in a hardware
    implementation of an A-buffer algorithm in the form of
    a rendering pipeline. Of course the algorithm can also
    be used in software to enhance an existing A-buffer
    The paper ends with the description of the list processing architecture for which the EXACT A-buffer has
    been built1


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