88 lines
2.7 KiB
Plaintext
88 lines
2.7 KiB
Plaintext
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.\" $XFree86$
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'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 24 September 1999
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.ds Re Release 1.2.1
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.ds Dp Jan 14 18:30
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.ds Dm 01 linestipp
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.ds Xs 10486 5 linestipple.gl
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.TH GLLINESTIPPLE 3G
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.SH NAME
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.B "glLineStipple
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\- specify the line stipple pattern
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.SH C SPECIFICATION
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void \f3glLineStipple\fP(
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GLint \fIfactor\fP,
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.nf
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.ta \w'\f3void \fPglLineStipple( 'u
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GLushort \fIpattern\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\fIpattern\fP\ \ 'u
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\f2factor\fP
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Specifies a multiplier for each bit in the line stipple pattern.
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If \f2factor\fP is 3,
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for example,
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each bit in the pattern is used three times
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before the next bit in the pattern is used.
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\f2factor\fP is clamped to the range [1, 256] and defaults to 1.
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.TP
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\f2pattern\fP
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Specifies a 16-bit integer whose bit pattern determines
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which fragments of a line will be drawn when the line is rasterized.
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Bit zero is used first; the default pattern is all 1's.
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.SH DESCRIPTION
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Line stippling masks out certain fragments produced by rasterization;
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those fragments will not be drawn.
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The masking is achieved by using three parameters:
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the 16-bit line stipple pattern \f2pattern\fP,
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the repeat count \f2factor\fP,
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and an integer stipple counter $s$.
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.P
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Counter $s$ is reset to 0 whenever \%\f3glBegin\fP is called,
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and before each line segment of a \%\f3glBegin\fP(\%\f3GL_LINES\fP)/\%\f3glEnd\fP
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sequence is generated.
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It is incremented after each fragment of a unit width aliased line segment is generated,
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or after each $i$ fragments of an $i$ width line segment are generated.
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The $i$ fragments associated with count $s$ are masked out if
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.sp
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.ce
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\f2pattern\fP bit $(s ~/~ "factor") ~roman mod~ 16$
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.sp
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is 0, otherwise these fragments are sent to the frame buffer.
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Bit zero of \f2pattern\fP is the least significant bit.
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.P
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Antialiased lines are treated as a sequence of $1 times width$ rectangles
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for purposes of stippling.
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Whether rectangle $s$ is rasterized or not depends on the fragment rule
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described for aliased lines,
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counting rectangles rather than groups of fragments.
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.P
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To enable and disable line stippling, call \%\f3glEnable\fP and \%\f3glDisable\fP
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with argument \%\f3GL_LINE_STIPPLE\fP.
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When enabled,
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the line stipple pattern is applied as described above.
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When disabled,
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it is as if the pattern were all 1's.
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Initially, line stippling is disabled.
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.SH ERRORS
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glLineStipple\fP
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is executed between the execution of \%\f3glBegin\fP
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and the corresponding execution of \%\f3glEnd\fP.
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.SH ASSOCIATED GETS
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\%\f3glGet\fP with argument \%\f3GL_LINE_STIPPLE_PATTERN\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_LINE_STIPPLE_REPEAT\fP
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.br
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\%\f3glIsEnabled\fP with argument \%\f3GL_LINE_STIPPLE\fP
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.SH SEE ALSO
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\%\f3glLineWidth(3G)\fP,
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\%\f3glPolygonStipple(3G)\fP
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