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Conversion to Fragments

The conversion of a group to fragments is controlled with

void PixelZoom ( float , float ) ;

Let be the current raster position (section 2.12). (If the current raster position is invalid, then DrawPixels  is ignored.) If a particular group (index or components) is the nth in a row and belongs to the mth row, consider the region in window coordinates bounded by the rectangle with corners

(either or may be negative). Any fragments whose centers lie inside of this rectangle (or on its bottom or left boundaries) are produced in correspondence with this particular group of elements.

A fragment arising from a group consisting of color data takes on the color index or color components of the group; the depth and texture coordinates are taken from the current raster position's associated data. A fragment arising from a depth component takes the component's depth value; the color and texture coordinates are given by those associated with the current raster position. In both cases texture coordinates s, t, and r are replaced with , , and , respectively. If q is less then or equal to zero, the results are undefined.

Groups arising from DrawPixels  with a format of STENCIL_INDEX are treated specially and are described in section 4.3.1.

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