sync code with last improvements from OpenBSD

doc/gl-docs/GL/gl/polygonstipple.3gl

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+'\" e
+'\"! eqn | mmdoc
+'\"macro stdmacro
+.ds Vn Version 1.2
+.ds Dt 24 September 1999
+.ds Re Release 1.2.1
+.ds Dp Jan 14 18:30
+.ds Dm 01 polygonst
+.ds Xs 22714 4 polygonstipple.gl
+.TH GLPOLYGONSTIPPLE 3G
+.SH NAME
+.B "glPolygonStipple
+\- set the polygon stippling pattern
+
+.SH C SPECIFICATION
+void \f3glPolygonStipple\fP(
+const GLubyte \fI*mask\fP )
+.nf
+.fi
+
+.EQ
+delim $$
+.EN
+.SH PARAMETERS
+.TP \w'\f2mask\fP\ \ 'u 
+\f2mask\fP
+Specifies a pointer to a $32 ~times~ 32$ stipple pattern that will be unpacked
+from memory in the same way that \%\f3glDrawPixels\fP unpacks pixels.
+.SH DESCRIPTION
+Polygon stippling,
+like line stippling
+(see \%\f3glLineStipple\fP),
+masks out certain fragments produced by rasterization,
+creating a pattern.
+Stippling is independent of polygon antialiasing.
+.P
+\f2mask\fP is a pointer to a $32 ~times~ 32$ stipple pattern that is stored
+in memory just like the pixel data supplied to a \%\f3glDrawPixels\fP
+call with 
+.I
+height
+and
+.I width
+both equal to 32, a pixel 
+of \%\f3GL_COLOR_INDEX\fP, and data type 
+of \%\f3GL_BITMAP\fP.
+That is,
+the stipple pattern is represented as a $32 ~times~ 32$ array
+of 1-bit color indices packed in unsigned bytes.
+\%\f3glPixelStore\fP parameters like \%\f3GL_UNPACK_SWAP_BYTES\fP
+and \%\f3GL_UNPACK_LSB_FIRST\fP affect the assembling of the bits into a
+stipple pattern.
+Pixel transfer operations
+(shift, offset, pixel map)
+are not applied to the stipple image,
+however.
+.P
+To enable and disable polygon stippling, call
+\%\f3glEnable\fP and \%\f3glDisable\fP
+with argument \%\f3GL_POLYGON_STIPPLE\fP. Polygon stippling is initially
+disabled. If it's enabled,
+a rasterized polygon fragment with window coordinates $x sub w$ and $y sub w$
+is sent to the next stage of the GL if and only if the
+($x sub w~roman mod~32$)th bit in the ($y sub w~roman mod~32$)th row
+of the stipple pattern is 1 (one).
+When polygon stippling is disabled, it is as if the stipple pattern
+consists of all 1's.
+.SH ERRORS
+\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glPolygonStipple\fP
+is executed between the execution of \%\f3glBegin\fP
+and the corresponding execution of \%\f3glEnd\fP.
+.SH ASSOCIATED GETS
+\%\f3glGetPolygonStipple\fP
+.br
+\%\f3glIsEnabled\fP with argument \%\f3GL_POLYGON_STIPPLE\fP
+.SH SEE ALSO
+\%\f3glDrawPixels(3G)\fP,
+\%\f3glLineStipple(3G)\fP,
+\%\f3glPixelStore(3G)\fP,
+\%\f3glPixelTransfer(3G)\fP