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Table of Contents
glPolygonStipple - set the polygon stippling pattern
void
glPolygonStipple( const GLubyte *mask )
eqn not supported
- mask
- Specifies a pointer to a $32 ~times~ 32$
stipple pattern that will be unpacked from memory in the same way that
glDrawPixels unpacks pixels.
Polygon stippling, like line stippling
(see glLineStipple), masks out certain fragments produced by rasterization,
creating a pattern. Stippling is independent of polygon antialiasing.
mask
is a pointer to a $32 ~times~ 32$ stipple pattern that is stored in memory
just like the pixel data supplied to a glDrawPixels call with height
and width both equal to 32, a pixel of GL_COLOR_INDEX, and data type
of GL_BITMAP. That is, the stipple pattern is represented as a $32 ~times~
32$ array of 1-bit color indices packed in unsigned bytes. glPixelStore parameters
like GL_UNPACK_SWAP_BYTES and GL_UNPACK_LSB_FIRST 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.
To enable and
disable polygon stippling, call glEnable and glDisable with argument GL_POLYGON_STIPPLE.
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.
GL_INVALID_OPERATION is generated if glPolygonStipple is
executed between the execution of glBegin and the corresponding execution
of glEnd.
glGetPolygonStipple
glIsEnabled with argument GL_POLYGON_STIPPLE
glDrawPixels(3G)
,
glLineStipple(3G)
, glPixelStore(3G)
, glPixelTransfer(3G)
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