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3.4. LINE SEGMENTS

Figure 3.6. The region used in rasterizing and finding corresponding coverage values for an antialiased line segment (an x-major line segment is shown).

incident on the starting endpoint of the segment. Each of these rectangles is either eliminated or produced according to the procedure given under Line Stipple, above, where “fragment” is replaced with “rectangle.” Each rectangle so produced is rasterized as if it were an antialiased polygon, described below (but culling, nondefault settings of PolygonMode, and polygon stippling are not applied).

3.4.3 Line Rasterization State

The state required for line rasterization consists of the floating-point line width, a 16-bit line stipple, the line stipple repeat count, a bit indicating whether stippling is enabled or disabled, and a bit indicating whether line antialiasing is on or off. In addition, during rasterization, an integer stipple counter must be maintained to implement line stippling. The initial value of the line width is 1.0. The initial value of the line stipple is F F F F16 (a stipple of all ones). The initial value of the line stipple repeat count is one. The initial state of line stippling is disabled. The initial state of line segment antialiasing is disabled.

3.4.4 Line Multisample Rasterization

If MULTISAMPLE is enabled, and the value of SAMPLE BUFFERS is one, then lines are rasterized using the following algorithm, regardless of whether line antialiasing (LINE SMOOTH) is enabled or disabled. Line rasterization produces a fragment for

Version 2.0 - October 22, 2004

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