81 lines
2.3 KiB
Plaintext
81 lines
2.3 KiB
Plaintext
'\" 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 polygonst
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.ds Xs 22714 4 polygonstipple.gl
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.TH GLPOLYGONSTIPPLE 3G
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.SH NAME
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.B "glPolygonStipple
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\- set the polygon stippling pattern
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.SH C SPECIFICATION
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void \f3glPolygonStipple\fP(
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const GLubyte \fI*mask\fP )
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.nf
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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'\f2mask\fP\ \ 'u
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\f2mask\fP
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Specifies a pointer to a $32 ~times~ 32$ stipple pattern that will be unpacked
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from memory in the same way that \%\f3glDrawPixels\fP unpacks pixels.
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.SH DESCRIPTION
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Polygon stippling,
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like line stippling
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(see \%\f3glLineStipple\fP),
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masks out certain fragments produced by rasterization,
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creating a pattern.
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Stippling is independent of polygon antialiasing.
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.P
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\f2mask\fP is a pointer to a $32 ~times~ 32$ stipple pattern that is stored
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in memory just like the pixel data supplied to a \%\f3glDrawPixels\fP
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call with
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.I
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height
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and
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.I width
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both equal to 32, a pixel
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of \%\f3GL_COLOR_INDEX\fP, and data type
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of \%\f3GL_BITMAP\fP.
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That is,
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the stipple pattern is represented as a $32 ~times~ 32$ array
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of 1-bit color indices packed in unsigned bytes.
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\%\f3glPixelStore\fP parameters like \%\f3GL_UNPACK_SWAP_BYTES\fP
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and \%\f3GL_UNPACK_LSB_FIRST\fP affect the assembling of the bits into a
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stipple pattern.
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Pixel transfer operations
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(shift, offset, pixel map)
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are not applied to the stipple image,
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however.
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.P
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To enable and disable polygon stippling, call
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\%\f3glEnable\fP and \%\f3glDisable\fP
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with argument \%\f3GL_POLYGON_STIPPLE\fP. Polygon stippling is initially
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disabled. If it's enabled,
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a rasterized polygon fragment with window coordinates $x sub w$ and $y sub w$
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is sent to the next stage of the GL if and only if the
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($x sub w~roman mod~32$)th bit in the ($y sub w~roman mod~32$)th row
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of the stipple pattern is 1 (one).
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When polygon stippling is disabled, it is as if the stipple pattern
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consists of all 1's.
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.SH ERRORS
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glPolygonStipple\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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\%\f3glGetPolygonStipple\fP
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.br
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\%\f3glIsEnabled\fP with argument \%\f3GL_POLYGON_STIPPLE\fP
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.SH SEE ALSO
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\%\f3glDrawPixels(3G)\fP,
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\%\f3glLineStipple(3G)\fP,
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\%\f3glPixelStore(3G)\fP,
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\%\f3glPixelTransfer(3G)\fP
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