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3.5.3 Antialiasing


Polygon antialiasing rasterizes a polygon by producing a fragment wherever the interior of the polygon intersects that fragment's square. A coverage value is computed at each such fragment, and this value is saved to be applied as described in section 3.10. An associated datum is assigned to a fragment by integrating the datum's value over the region of the intersection of the fragment square with the polygon's interior and dividing this integrated value by the area of the intersection. For a fragment square lying entirely within the polygon, the value of a datum at the fragment's center may be used instead of integrating the value across the fragment.

Polygon stippling operates in the same way whether polygon antialiasing is enabled or not. The polygon point sampling rule defined in section 3.5.1, however, is not enforced for antialiased polygons.

David Blythe
Sat Mar 29 02:23:21 PST 1997